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IFundamentals

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2003 by CRC Press LLC

1Earthquakes: AHistorical Perspective1.1 Introduction

Global Earthquake Impacts

1.2 Review of Historical EarthquakesPre-Twentieth Century Events Early Twentieth Century

Events Mid-Century Events First Turning Point

Second Turning Point

Defining TermsReferencesFurther Reading

Let us look at the facts.

Terence

Adelphoe, l. 796

1.1 Introduction

Earthquakes are a major problem for mankind, killing thousands each year. A review ofTable 1.1shows,

for example, that an average of almost 17,000 persons per year were killed in the twentieth century. 1

Earthquakes are also multifaceted, sometimes causing death and destruction in a wide variety of ways,

from building collapse to conflagrations, tsunamis, and landslides. This chapter therefore reviews selected

earthquakes and the damage they have caused, to inculcate in the reader the magnitude and complexity

of the problem earthquakes pose for mankind. To do this, we first review in this introduction some basic

statistics on damage. Section 1.2, the heart of this chapter, then reviews selected earthquakes, chosen for

their particular damaging effects, or because the earthquake led to a significant advance in mitigation.

This review is focused. It is relatively brief on earlier earthquakes, which are mentioned largely for

historical interest or because you should be aware of them as portents for future events; however, the

review is lengthier on selected recent events, especially U.S. events, because these provide the best record

on the performance of modern structures. Table 1.2shows selected U.S. earthquakes.

Based on this review, the next section then extracts important lessons, following which we conclude

with a brief history of the response to earthquakes.

1The average is still more than 10,000 if the single largest event (Tangshan, 1976) is omitted.

Charles ScawthornConsulting Engineer

Berkeley, CA

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TABLE 1.1 Selected Earthquakes Since 1900 (Fatalities Greater than 1,000)a

Year Day-Month Location Latitude Longitude Deaths M

Comments/Damage

($ millions)

1902 19-Apr Guatemala 14N 91W 2,000 7.5

16-Dec Turkestan 40.8N 72.6E 4,500 6.41903 19-Apr Turkey 39.1N 42.4E 1,700

28-Apr Turkey 39.1N 42.5E 2,200 6.3

1905 04-Apr India, Kangra 33.0N 76.0E 19,000 8.6

08-Sep Italy, Calabria 39.4N 16.4E 2,500 7.9

1906 31-Jan Colombia 1N 81.5W 1,000 8.9

16-Mar Taiwan, Kagi 23.6N 120.5E 1,300 7.1

18-Apr San Francisco, CA 38N 123W 2,000+ 8.3 Conflagration

17-Aug Chile, Santiago 33S 72W 20,000 8.6 Conflagration

1907 14-Jan Jamaica, Kingston 18.2N 76.7W 1,600 6.5 Conflagration

21-Oct Central Asia 38N 69E 12,000 8.1

1908 28-Dec Italy, Messina 38N 15.5E 70,000 7.5 Deaths possibly 100,000

1909 23-Jan Iran 33.4N 49.1E 5,500 7.3

1912 09-Aug Turkey, Marmara Sea 40.5N 27E 1,950 7.8

1915 13-Jan Italy, Avezzano 42N 13.5E 29,980 7.5

1917 21-Jan Indonesia, Bali 8.0S 115.4E 15,000

30-Jul China 28.0N 104.0E 1,800 6.5

1918 13-Feb China, Canton 23.5N 117.0E 10,000 7.3

1920 16-Dec China, Gansu 35.8N 105.7E 200,000 8.6 Major fractures,

landslides

1923 24-Mar China 31.3N 100.8E 5,000 7.3

25-May Iran 35.3N 59.2E 2,200 5.7

01-Sep Japan, Kanto 35.0N 139.5E 143,000 8.3 $2800, conflagration

1925 16-Mar China, Yunnan 25.5N 100.3E 5,000 7.1

1927 07-Mar Japan, Tango 35.8N 134.8E 3,020 7.9

22-May China, nr Xining 36.8N 102.8E 200,000 8.3 Large fractures1929 01-May Iran 38N 58E 3,300 7.4

1930 06-May Iran 38.0N 44.5E 2,500 7.2

23-Jul Italy 41.1N 15.4E 1,430 6.5

1931 31-Mar Nicaragua 13.2N 85.7W 2,400 5.6

1932 25-Dec China, Gansu 39.7N 97.0E 70,000 7.6

1933 02-Mar Japan, Sanriku 39.0N 143.0E 2,990 8.9

25-Aug China 32.0N 103.7E 10,000 7.4

1934 15-Jan India, Bihar-Nepal 26.6N 86.8E 10,700 8.4

1935 20-Apr Formosa 24.0N 121.0E 3,280 7.1

30-May Pakistan, Quetta 29.6N 66.5E 30,000 7.5 Deaths possibly 60,000

16-Jul Taiwan 24.4N 120.7E 2,700 6.5

1939 25-Jan Chile, Chillan 36.2S 72.2W 28,000 8.3 $100

26-Dec Turkey, Erzincan 39.6N 38E 30,000 8

1940 10-Nov Romania 45.8N 26.8E 1,000 7.3

1942 26-Nov Turkey 40.5N 34.0E 4,000 7.6

20-Dec Turkey, Erbaa 40.9N 36.5E 3,000 7.3 Some reports of 1,000

killed

1943 10-Sep Japan, Tottori 35.6N 134.2E 1,190 7.4

26-Nov Turkey 41.0N 33.7E 4,000 7.6

1944 15-Jan Argentina, San Juan 31.6S 68.5W 5,000 7.8 Deaths possibly 8,000

01-Feb Turkey 41.4N 32.7E 2,800 7.4 Deaths possibly 5,000

07-Dec Japan, Tonankai 33.7N 136.2E 1,000 8.3

1945 12-Jan Japan, Mikawa 34.8N 137.0E 1,900 7.1

27-Nov Iran 25.0N 60.5E 4,000 8.21946 31-May Turkey 39.5N 41.5E 1,300 6

10-Nov Peru, Ancash 8.3S 77.8W 1,400 7.3 Landslides, great

destruction

20-Dec Japan, Tonankai 32.5N 134.5E 1,330 8.4


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TABLE 1.1 (CONTINUED) Selected Earthquakes Since 1900 (Fatalities Greater than 1,000) a


Comments/Damage

($ millions)

1948 28-Jun Japan, Fukui 36.1N 136.2E 5,390 7.3 Conflagration

05-Oct Turkmenistan 38.0N 58.3E 110,000 7.31949 05-Aug Ecuador, Ambato 1.2S 78.5E 6,000 6.8 Large landslides

1950 15-Aug India, Assam; Tibet 28.7N 96.6E 1,530 8.7 Great topographical

changes

1954 09-Sep Algeria, Orleansvl. 36N 1.6E 1,250 6.8

1957 27-Jun USSR (Russia) 56.3N 116.5E 1,200

02-Jul Iran 36.2N 52.7E 1,200 7.4

13-Dec Iran 34.4N 47.6E 1,130 7.3

1960 29-Feb Morocco, Agadir 30N 9W 10,000 5.9 Deaths possibly 15,000

22-May Chile 39.5S 74.5W 4,000 9.5 Deaths possibly 5,000

1962 01-Sep Iran, Qazvin 35.6N 49.9E 12,230 7.3

1963 26-Jul Yugoslavia, Skopje 42.1N 21.4E 1,100 6 Shallow depth just under

city

1966 19-Aug Turkey, Varto 39.2N 41.7E 2,520 7.1

1968 31-Aug Iran 34.0N 59.0E 12,000 7.3 Deaths possibly 20,000

1969 25-Jul Eastern China 21.6N 111.9E 3,000 5.9

1970 04-Jan Yunnan, China 24.1N 102.5E 10,000 7.5

28-Mar Turkey, Gediz 39.2N 29.5E 1,100 7.3

31-May Peru 9.2S 78.8W 66,000 7.8 Great rockslide; $500

1972 10-Apr Iran, southern 28.4N 52.8E 5,054 7.1

23-Dec Nicaragua 12.4N 86.1W 5,000 6.2 Managua

1974 10-May China 28.2N 104.0E 20,000 6.8

28-Dec Pakistan 35.0N 72.8E 5,300 6.2

1975 04-Feb China 40.6N 122.5E 10,000 7.4

06-Sep Turkey 38.5N 40.7E 2,300 6.7

1976 04-Feb Guatemala 15.3N 89.1W 23,000 7.5 $6,00006-May Italy, northeastern 46.4N 13.3E 1,000 6.5

25-Jun New Guinea 4.6S 140.1E 422 7.1 West Irian

27-Jul China, Tangshan 39.6N 118.0E 255,000 8 Deaths possibly 655,000;

$2,000

16-Aug Philippines 6.3N 124.0E 8,000 7.9 Mindanao

24-Nov Iran-USSR border 39.1N 44.0E 5,000 7.3

1977 04-Mar Romania 45.8N 26.8E 1,500 7.2

1978 16-Sep Iran, Tabas 33.2N 57.4E 15,000 7.8 $11

1980 10-Oct Algeria, El Asnam 36.1N 1.4E 3,500 7.7

23-Nov Italy, southern 40.9N 15.3E 3,000 7.2

1981 11-Jun Iran, southern 29.9N 57.7E 3,000 6.9

28-Jul Iran, southern 30.0N 57.8E 1,500 7.3

1982 13-Dec W. Arabian Peninsula 14.7N 44.4E 2,800 6

1983 30-Oct Turkey 40.3N 42.2E 1,342 6.9

1985 19-Sep Mexico, Michoacan 18.2N 102.5W 9,500 8.1 Deaths possibly 30,000

1986 10-Oct El Salvador 13.8N 89.2W 1,000 5.5

1987 06-Mar Colombia-Ecuador 0.2N 77.8W 1,000 7

1988 20-Aug Nepal-India border 26.8N 86.6E 1,450 6.6

07-Dec Armenia, Spitak 41.0N 44.2E 25,000 7 $16,200

1990 20-Jun Iran, western 37.0N 49.4E 40,000 7.7 Deaths possibly 50,000

16-Jul Philippines, Luzon 15.7N 121.2E 1,621 7.8 Landslides, subsidence

1991 19-Oct India, northern 30.8N 78.8E 2,000 7

1992 12-Dec Indonesia, Flores 8.5S 121.9E 2,500 7.5 Tsunami wave height

25 m

1993 29-Sep India, southern 18.1N 76.5E 9,748 6.31995 16-Jan Japan, Kobe 34.6N 135E 6,000 6.9 $100,000, conflagration

27-May Sakhalin Island 52.6N 142.8E 1,989 7.5

1997 10-May Iran, northern 33.9N 59.7E 1,560 7.5 4,460 injured; 60,000

homeless


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TABLE 1.1 (CONTINUED) Selected Earthquakes Since 1900 (Fatalities Greater than 1,000) a


Comments/Damage

($ millions)

1998 04-Feb Afghanistan 37.1N 70.1E 2,323 6.1 Also Tajikistan

30-May Afghanistan 37.1N 70.1E 4,000 6.9 Also Tajikistan17-Jul Papua New Guinea 2.96S 141.9E 2,183 7.1 Tsunami

1999 25-Jan Colombia 4.46N 75.82W 1,185 6.3

17-Aug Turkey 40.7N 30.0E 17,118 7.4 50,000 injured; $7,000

20-Sep Taiwan 23.7N 121.0E 2,297 7.6 8,700 injured; 600,000homeless

2001 26-Jan India, Bhuj 23.3 N 70.3 E 19,988 7.7 166,812 injured; 600,000homeless

Total Events = 108 Total Deaths = 1,762,802

aMagnitude scale varies.

Source:National Earthquake Information Center, Golden, CO, http://neic.usgs.gov/neis/eqlists/eqsmajr.html.

TABLE 1.2 Selected U.S. Earthquakesa

Year Month Day Latitude Longitude M MMI Fatalities

Damage

US $

(millions) Locale

1755 11 18 8 Massachusetts, Nr Cape Ann1774 2 21 7 Eastern Virginia (MMI from Sta)1791 5 16 8 Connecticut, E. Haddam (MMI from

Sta)1811 12 16 36N 90W 8.6 Missouri, New Madrid1812 1 23 36.6N 89.6W 8.4 12 Missouri, New Madrid

2 7 36.6N 89.6W 8.7 12 Missouri, New Madrid1817 10 5 8 Massachusetts, Woburn (MMI from

Sta)1836 6 10 38N 122W 10 California1838 6 0 37.5N 123W 10 California1857 1 9 35N 119W 8.3 7 California, Central1865 10 8 37N 122W 9 California, San Jose, Santa Cruz1868 4 3 19N 156W 10 81 Hawaii

10 21 37.5N 122W 6.8 10 3 California, Hayward1872 3 26 36.5N 118W 8.5 10 50 California, Owens Valley 1886 9 1 32.9N 80W 7.7 9 60 5 South Carolina, Charleston1892 2 24 31.5N 117W 10 California, San Diego County

4 19 38.5N 123W 9 California, Vacaville, Winters5 16 14N 143W Guam, Agana

1897 5 31 5.8 8 Virignia, Giles County (Mbfrom Sta)1899 9 4 60N 142W 8.3 Alaska, Cape Yakataga

1906 4 18 38N 123W 8.3 11 2,000 400 California, San Francisco (fire)1915 10 3 40.5N 118W 7.8 Nevada, Pleasant Valley 1925 6 29 34.3N 120W 6.2 13 8 California, Santa Barbara1927 11 4 34.5N 121W 7.5 9 California, Lompoc1933 3 11 33.6N 118W 6.3 115 40 California, Long Beach1934 12 31 31.8N 116W 7.1 10 California, Baja, Imperial Valley 1935 10 19 46.6N 112W 6.2 2 19 Montana, Helena1940 5 19 32.7N 116W 7.1 10 9 6 California, southeast of El Centro1944 9 5 44.7N 74.7W 5.6 2 New York, Massena1949 4 13 47.1N 123W 7 8 8 25 Washington, Olympia1951 8 21 19.7N 156W 6.9 Hawaii1952 7 21 35N 119W 7.7 11 13 60 California, Kern County 1954 12 16 39.3N 118W 7 10 Nevada, Dixie Valley 1957 3 9 51.3N 176W 8.6 3 Alaska

1958 7 10 58.6N 137W 7.9 5 Alaska, Lituyabay (landslide)1959 8 18 44.8N 111W 7.7 Montana, Hebgen Lake1962 8 30 41.8N 112W 5.8 2 Utah1964 3 28 61N 148W 8.3 131 540 Alaska1965 4 29 47.4N 122W 6.5 7 7 13 Washington, Seattle1971 2 9 34.4N 118W 6.7 11 65 553 California, San Fernando1975 3 28 42.1N 113W 6.2 8 1 Idaho, Pocatello Valley


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1.1.1 Global Earthquake Impacts

Globally, earthquakes have caused massive death and destruction up to the present day.Table 1.1provides

a list of selected twentieth century earthquakes with fatalities of approximately 1,000 or more, and

Table 1.3 provides a list of earthquakes with fatalities of approximately 50,000 or more prior to the

twentieth century. All the earthquakes are in the Trans-Alpide belt or the circum-Pacific Ring of Fire

(Figure 1.1),and the great loss of life is almost invariably due to low-strength masonry buildings and

dwellings. Exceptions to this rule are few in number but include the 1923 Kanto (Japan) earthquake,where most of the approximately 140,000 fatalities were due to fire; the 1970 Peru earthquake, where

large landslides destroyed whole towns; the 1988 Armenian event, where 25,000 were killed in Spitak and

Leninakan, mostly due to poor quality, precast construction; and the 1999 Marmara (Turkey) earth-

quakes, where 17,000 were killed in a rapidly urbanizing area where many mid-rise, soft story, reinforced

concrete buildings collapsed, due largely to inadequate code enforcement [Scawthorn, 2000].

The absolute trend for earthquake fatalities is not decreasing, as indicated inFigure 1.2,although if

population increase is taken into account, some relative decrease is occurring. Economic and insured

losses for all sources, as indicated inFigure 1.3, are increasing. The 1995 Kobe (Japan) earthquake, with

unprecedented losses of $100 billion,2may only be a harbinger of even greater losses if an earthquake

strikes Tokyo, Los Angeles, San Francisco, or some other large urban region. To understand how these

losses occur and how they might be reduced, it is valuable to review some important earthquakes from

previous centuries as well as very recent earthquakes.

TABLE 1.2 (CONTINUED) Selected U.S. Earthquakesa

Year Month Day Latitude Longitude M MMI Fatalities

Damage

US $

(millions) Locale

1975 8 1 39.4N 122W 6.1 6 California, Oroville Reservoir11 29 19.3N 155W 7.2 9 2 4 Hawaii

1980 1 24 37.8N 122W 5.9 7 1 4 California, Livermore5 25 37.6N 119W 6.4 7 2 California, Mammoth Lakes7 27 38.2N 83.9W 5.2 1 Kentucky, Maysville

11 8 41.2N 124W 7 7 5 3 California, northern coast1983 5 2 36.2N 120W 6.5 8 31 California, central, Coalinga

10 28 43.9N 114W 7.3 2 13 Idaho, Borah Peak 11 16 19.5N 155W 6.6 8 7 Hawaii, Kapapala

1984 4 24 37.3N 122W 6.2 7 8 California, Morgan Hill1986 7 8 34N 117W 6.1 7 5 California, Palm Springs1987 10 1 34.1N 118W 6 8 8 358 California, Whittier

11 24 33.2N 116W 6.3 6 2 California, Superstition Hills1989 6 26 19.4N 155W 6.1 6 Hawaii

10 18 37.1N 122W 7.1 9 62 6,000 California, Loma Prieta1990 2 28 34.1N 118W 5.5 7 13 California, southern, Claremont,

Covina1992 4 23 34N 116W 6.3 7 California, Joshua Tree

4 25 40.4N 124W 7.1 8 66 California, Humboldt, Ferndale6 28 34.2N 117W 6.7 8 California, Big Bear6 28 34.2N 116W 7.6 9 3 92 California, Landers, Yucca Valley 6 29 36.7N 116W 5.6 California-Nevada border T.S.

1993 3 25 45N 123W 5.6 7 Washington-Oregon9 21 42.3N 122W 5.9 7 2 Oregon, Klamath Falls

1994 1 16 40.3N 76W 4.6 5 Pennsylvania (felt Canada)1 17 34.2N 119W 6.8 9 57 30,000 California, Northridge2 3 42.8N 111W 6 7 Wyoming, Afton

1995 10 6 65.2N 149W 6.4 Alaska (oil pipeline damaged)

aMagnitude scale varies.

Source:National Earthquake Information Center (1996). Database of Significant Earthquakes Contained in SeismicityCatalogs, Golden, CO.

2The largest previous loss due to any natural hazard was in the 1994 Northridge earthquake, estimated at about$40 billion.


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1.2 Review of Historical Earthquakes

This section presents a review of selected historical earthquakes. The review is divided into several parts:

pre-twentieth century, early and mid-twentieth century, and two periods termed first andsecond turningpoints,respectively. Magnitudes (M, seeChapter 4)are indicated but, especially for the earlier events, are

necessarily estimated rather than measured, and are therefore quite approximate; later events are indicated

on the moment magnitude scale (Mw) where possible. Similarly, seismic intensity maps are provided

when available, in most cases using the Modified Mercalli Intensity scale (MMI, see Chapter 4).

TABLE 1.3 Selected Pre-Twentieth Century Earthquakes (Fatalities Greater than 50,000)

Year Month Day Location Deaths M Comments

856 12 22 Iran, Damghan 200,000

893 3 23 Iran, Ardabil 150,000

1138 8 9 Syria, Aleppo 230,0001268 Asia Minor, Silicia 60,000

1290 9 China, Chihli 100,000

1556 1 23 China, Shansi 830,000

1667 11 Caucasia, Shemakha 80,000

1693 1 11 Italy, Sicily 60,000

1727 11 18 Iran, Tabriz 77,000

1755 11 1 Portugal, Lisbon 70,000 8.7 Great tsunami, fires

1783 2 4 Italy, Calabria 50,000

Source:National Earthquake Information Center, Golden, CO, http://neic.usgs.gov/neis/eqlists/eqsmosde.html.

FIGURE 1.1 Selected earthquakes since 1900 (fatalities greater than 1000).

100,000 - 255,000

50,000 - 100,000

20,000 - 50,000

10,000 - 20,0005,000 - 10,000

2,000 - 5,000

1,000 - 2,000

1,000 or less

(5)

(3)

(9)

(14)(14)

(31)

(32)

(1)

Earthquakes of 20th CenturyNumber of Deaths

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1.2.1 Pre-Twentieth Century Events

AsTable 1.3indicates, truly catastrophic earthquakes have occurred for many centuries. Herein we review

very briefly only a few of these events, selected for their historical importance.

1.2.1.1 1755: November 1, Lisbon, Portugal (M9)

The earthquake began at 9:30 on November 1, 1755, and was centered in the Atlantic Ocean, about

200 km WSW of Cape St. Vincent.3Lisbon, the Portuguese capital, was the largest and most important

of the cities damaged; however, severe shaking also was felt in France, Switzerland, and Northern Italy,and in North Africa shaking was felt with heavy loss of life in Fez and Mequinez. A devastating fire

following the earthquake raged for five days and destroyed a large part of Lisbon.

FIGURE 1.2 Twentieth century global earthquake fatalities, by decade.

FIGURE 1.3 Trend of worldwide economic and insured losses. (From Munich Reinsurance.)

3The following discussions are largely drawn from Kozak and James [n.d.].

1

10

100

1,000

10,000

100,000

1,000,000

10,000,000

1 4 8 1032 5 6 7 9

80

70

60

50

40

30

20

10

020001995199019851980197519701965196019551950

US$ 160bn

Economic losses (2000 values)

of which insured losses (2000 values)

Trend of economic losses

Trend of insured losses

(Amounts in US$ bn)


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A very strong tsunami caused heavy destruction along the coasts of Portugal, southwestern Spain, and

western Morocco. About 30 min after the quake, a large wave swamped the area near Bugie Tower on

the mouth of the Tagus. The area between Junqueria and Alcantara in the western part of the city was

the most heavily damaged by a total of three waves with maximum height estimated at 6 m, each dragging

people and debris out to sea and leaving exposed large stretches of the river bottom. In Setubal, 30 km

south of Lisbon, the water reached the first floor of buildings. The destruction was greatest in Algarve,

southern Portugal, where the tsunami dismantled some coastal fortresses and, in the lower levels, razed

houses. In some places, the waves crested at more than 30 m. The tsunami reached, with less intensity,

the coasts of France, Great Britain, Ireland, Belgium, and Holland. In Madeira and in the Azores, damage

was extensive and many ships were in danger of being wrecked. The tsunami crossed the Atlantic Ocean,

reaching the Antilles in the afternoon. Reports from Antigua, Martinique, and Barbados note that the

sea first rose more than a meter, followed by large waves.

The oscillation of suspended objects at great distances from the epicenter indicates an enormous area

of perceptibility. The observation of seiches as far away as Finland suggests a magnitude approaching

9.0. Between the earthquake and the fires and tsunami that followed (which were probably more damagingthan the actual earthquake), approximately 10,000 to 15,000 people died (population: 275,000) [Kendrick,

1956]. As Kozak and James [n.d.] note, most depictions of damaged Lisbon are fanciful; Figure 1.4,

however, is an accurate depiction of a portion of central Lisbon following the earthquake.

The 1755 Lisbon earthquake was felt across broad parts of Europe. It occurred at the height of the

Enlightenment and on the eve of the Industrial Revolution. Its massive death and destruction of one of

the largest and most beautiful cities in Europe shook thinkers such as Voltaire, whose inherent optimism

was deeply shaken by the event, as can be seen in his poem, Poeme sur le desastre de Lisbonne:

Did Lisbon, which is no more, have more vices

Than London and Paris immersed in their pleasures?

Lisbon is destroyed, and they dance in Paris!

Rousseau disagreed with Voltaires change in philosophy, taking a more pragmatic view:

it was not Nature that collected twenty thousand houses on the site if the inhabitants of this big

city had been more equally dispersed and more lightly housed, the damage would have been much

less. [Quoted in Goldberg, 1989]

From a scientific viewpoint, changes were made in building construction in Lisbon following the earthquake,

such as thegaiola(an internal wooden cage for masonry buildings), as well as in the planning of reconstructed

Lisbon; however, while the gaiola survived to the 1920s in Portugal, it was little publicized and not utilized

elsewhere [Tobriner, 1984]. Together with the 1783 Calabrian earthquakes, the Lisbon earthquake strengthened

nascent European efforts at construction of seismological instruments [Dewey and Byerly, 1969].

1.2.1.2 1755: November 18, Cape Ann, MA (M7)

The heaviest damage due to this earthquake occurred in the region around Cape Ann and Boston. At

Boston, much of the damage was confined to an area of infilled land near the wharfs. There, about 100

FIGURE 1.4 Lisbon, Portugal, ruins of Praca de Patri-

arcal (Patriarchal Square) (copper engraving, Paris,

1757), Le Bas series, Bibliothque Nationale. Colleo de

algunas ruinas de Lisboa, 1755. Drawings executed by

Messrs Paris et Pedegache. Paris: Jacques-Phillippe

Le Bas, 1757. (From the Kozak Collection of Images of

Historical Earthquakes, National Information Service for

Earthquake Engineering, University of California, Berke-

ley. With permission.)


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1.2.1.5 1886: Charleston, SC

The largest and by far the most destructive earthquake in the southeast United States occurred on August

31, 1886, with epicenter about 15 miles northwest of Charleston, SC (32.9 N, 80.0 W). The first shock

was at 21:51, with magnitude of 7.6 [Johnston, 1991], and the second about 8 min later. The earthquake

was felt over 2.5 million mi2(from Cuba to New York, and Bermuda to the Mississippi), equivalent to a

FIGURE 1.5 Isoseismal map of the December 16, 1811 earthquake. The arabic numbers give the Modified Mercalli

Intensities at each data point. (From Nuttli, O.W. 1979. Seismicity of the Central United States,in Geology in the

Siting of Nuclear Power Plants,Hatheway, A.W. and McClure, C.R., Eds., Geological Society of America, Rev. Eng.

Geol,4, 6794. With permission.)

54

6

6

6 5

4

8

8

8 6

6

6

66

6

66

6

6

4

5

5

5

F

NF

NF

NF

NF

NFNF NF

NF

NF

F

F

F

F

F

NF

NFF

5

5

5

5

5

5

5

5

5

4

5

67

67

67

6756

56

56

56

NF

F

0

78

78

56

56

5656

F

477

7

7

11

11

7

7

7

7

7

4

DEC. 16, 1811(02:15 A.M.)

KM 300


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radius of more than 800 mi; the strongly shaken portion extended to 100 mi. Approximately 110 persons

lost their lives and 90% of the brick structures in Charleston were damaged [Dutton, 1889]. Damaging

secondary effects were fires, ruptured water and sewage lines, damaged wells, flooding from a cracked

dam in Langley, SC, and in the highest intensity area bent railroad tracks, throwing one train off the

tracks. Dollar damage estimates in 1886 dollars were about $5.5 million. Four decades later, Freeman

[1932] made a careful study of the damage, concluding that taking the city as a whole, the ratio of

earthquake damage to sound value was small in Charleston, and probably averaged little if any more

than 10%.The bending of rails and lateral displacement of tracks due to ground displacements were very evident

in the epicentral region, though not at Charleston. There were severe bends of the track in places and

sudden and sharp depressions of the roadbed. At one place, there was a sharp S-curve. At a number of

locations, the effect on culverts and other structures demonstrated strong vertical force in action at the

FIGURE 1.6 Modifi

ed Mercalli Intensity map, 1857 Fort Tejon, CA, earthquake. (From Stover, C.W. and Coffman,J.L. 1993. Seismicity of the United States, 15681989 (revised). U.S. Geological Survey Professional Paper 1527,

Government Printing Office, Washington, D.C.)

NEVADA UTAH

ARIZONA

CALIFORNIA

II-VIVII-IX

IX

Las Vegas

Bakersfield

Sacramento

San Francisco

Monterey

Reno

114116118120122124

40

38

36

34

32

UNITEDSTATES

MEXICO

GULF OF

CALIFORNIA

San Diego

Blythe

Los AngelesPA

CI

FIC

OC

EA

N

EXPLANATION

Epicenter

Intensity 9

0 100 KILOMETERS


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600 km. The total felt area included most of California and parts of western Nevada and southern Oregon

(Figure 1.9). This earthquake caused the most lengthy fault rupture observed in the contiguous United

States, i.e., from San Juan Bautista to Point Arena, where it passes out to sea, with additional displacement

observed farther north at Shelter Cove in Humbolt County, indicating a potential total length of rupture

of 430 km. Fault displacements were predominantly right lateral strike-slip, with the largest horizontal

displacement6.4 m occurring near Point Reyes Station in Marin County (Figure 1.10). The surface

of the ground was torn and heaved into furrow-like ridges. Roads crossing the fault were impassable,

and pipelines were broken.

On or near the San Andreas fault, some buildings were destroyed but other buildings, close to or even

intersected by the fault, sustained nil to only light damage (Figure 1.11). South of San Francisco, the

concrete block gravity-arch dam of the Crystal Springs Reservoir (dam only 100 to 200 yards from the

fault, reservoir on the fault) was virtually undamaged by the event, and the San Andreas earthen dam,

whose abutment was intersected by the fault rupture, was also virtually undamaged, although surround-

ing structures sustained significant damage or were destroyed [Lawson et al., 1908].

The earthquake and resulting fires caused an estimated 3000 deaths and $524 million in property loss.

One pipeline that carried water from San Andreas Lake to San Francisco was broken, shutting off the

water supply to the city. However, distorted ground within the city resulted in hun dreds of breaks in

water mains, which were the actual source of lack of water supply for firefighting (Figure 1.12).Fires

that ignited in San Francisco soon after the onset of the earthquake burned for three days because of thelack of water to control them (Figure 1.13). Damage in San Francisco was devastating, with 28,000

buildings destroyed, although 80% of the damage was due to the fire, rather than the shaking (Figure 1.14).

Fires also intensified the loss at Fort Bragg and Santa Rosa. Damage was severe at Stanford University,

south of San Francisco (Figure 1.15). Although Santa Rosa lies about 30 km from the San Andreas fault,

FIGURE 1.8 (A) Damage in central Charleston, (B) bent rails due to ground movement, and (C) large sand boils

indicating liquefaction. (From Peters, K.E. and Herrmann, R.B., Eds. n.d. First-Hand Observations of the Charleston

Earthquake of August 31, 1886 and Other Earthquake Materials, South Carolina Geological Survey Bulletin 41.)

(A)

(B) (C)


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damage to property was severe and 50 people were killed. The earthquake also was severe in the LosBanos area of the western San Joaquin Valley, where the MMI was IX more than 48 km from the fault

zone. The maximum intensity of XI was based on geologic effects, but the highest intensity based on

damage was IX. Several foreshocks probably occurred, and many aftershocks were reported, some of

which were severe [Stover and Coffman, 1993].

FIGURE 1.9 MMI map of 1906 San Francisco earthquake. (From Stover, C.W. and Coffman, J.L. 1993. Seismicity

of the United States, 15681989(revised). U.S. Geological Survey Professional Paper 1527, U.S. Government Printing

Office, Washington, D.C.)

CALIFORNIA

IVVV

VI

VI

Sacramento

Val

Santa Rosa

VI

V

IV

VI

VIVI

IV II.8

NEVADA

Reno

Bishop

Eureka

Winnemucca

OREGON

Eugene

Ashland

IDAHO

Boise

V

VI

IX

VIIVIII

VII

IVLos Angeles

San DiegoUnited

States

Mexico

0.10

Bakersfield

44

EXPLANATION

Epicenter1X Intensity 9KILOMETERS

PacificO

cean

San Francisco

Monterey

Ukiah

42

124 122 120 118 116

1000

VIII

VII

40

Arcata

36

38

34

VII

San Jose


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FIGURE 1.13 This row of two-story buildings tilted

away from the street when the ground beneath the foun-

dations slumped. Such ground failures contributed to the

shaking intensity and to the subsequent building damage.

This photo was taken before fire destroyed the entire

block. Note billowing smoke in the sky. (Photo: NOAA/

NGDC, wysiwyg://122/http://www.ngdc.noaa.gov/seg/

hazard/slideset/earthquakes/2/2_slides.html.)

FIGURE 1.14 (A) Collapsed San Francisco City Hall; (B) the damndest finest ruins,this view looks east toward

Market Street in San Francisco. Wooden buildings, one to three stories high, with brick or stone-work fronts, were

closely interspersed with two- to eight-story brick buildings. Mingled with these were modern office buildings. Here

the fire burned fiercely. In its aftermath, the streets were heaped with rubble to a depth of a meter or more and were

nearly impassible. Because of the heat of the fire, much of the damage due directly to the shock was concealed or

obliterated in this part of the city. (Photo: Eric Swenson, U.S. Geological Survey.) (C) One of the camps set up for

earthquake victims is depicted. Similar camps were established on the hills, parks, and open spaces of the city. Five

days after the earthquake rains brought indescribable suffering to the tens of thousands of people camped in theopen. Few people had waterproof covering initially. The downpour aggravated the unsanitary conditions of the camps

and added numbers of pneumonia cases to the already crowded regular and temporary hospitals of the city. Eventually

tents such as these were provided to the 300,000 homeless. (Photo: Eric Swenson, U.S. Geological Survey. From

National Geophysical Data Center, wysiwyg://122/http://www.ngdc.noaa.gov/seg/hazard/slideset/earthquakes/2/

2_slides.html.)

(A)

(B) (C)

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of various construction types were present that the study drew clear lessons from the event: that well-

engineered steel and reinforced concrete buildings could survive shaking of this intensity with little

damage. It was also noted that great earthquakes are followed by an interval of 50 or 100 years duringwhich no earthquakes occur[USGS, 1907] (which turned out to be true; see below). As a result, for

many years the event was more popularly known as the Fire, and earthquake provisions were not

especially emphasized in building codes in California until after the 1925 Santa Barbara and 1933 Long

Beach events (see Section 1.2.2.3).

FIGURE 1.15 Memorial Church as seen from the innerquadrangle at Stanford University, Palo Alto. The stone

tower of the church fell and destroyed the parts of the

roof immediately around the tower. The gable on the

north end of the church was thrown outward into the

quadrangle. (Photo: W.C. Mendenhall, U.S. Geological

Survey, wysiwyg://122/http://www.ngdc.noaa.gov/seg/haz-

ard/slideset/earthquakes/2/2_slides.html.)

FIGURE 1.16 Map of San Francisco showing district burned in 1907. (From U.S. Geological Survey. 1907. The San

Francisco Earthquake and Fire of April 18, 1906 and Their Effects on Structures and Structural Materials. Bulletin 324,

Washington, D.C.)

Principal distribution mains.

Salt-water system.Old shore line.

Boundary line of burned district.

Principal earthquake breaks in streets.

Districts covered largelyby brick structures.

Cisterns in service.

0 1000 2000 3000 FEET

BAYOFSANFR

ANCISC

O

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program of investigation into seismology and earthquake engineering would have emerged from the 1906

event. However, as Maher5observes [Carder, 1965]:

The great San Francisco earthquake of Apr. 18, 1906, resulted in a temporary impetus in earthquake

investigation. However, after the excitement had died down, interest in research on earthquakes

declined, partly because of activity by pressure groups who considered that the dissemination ofinformation about earthquakes was detrimental to business.

The existence of pressure groupsis confirmed by Branner [1913].6

1.2.2.2 1923: September 1, Kanto, Japan (M 7.9)

The M7.9 Kanto earthquake occurred at 11:58 a.m., September 1, 1923, with epicenter beneath Sagami

Bay (Figure 1.18). The Tokyo region (actually, Mt. Fuji) is the junction of four tectonic plates (Philippine

Sea, Pacific, Eurasian, and North American), and the subduction of the Pacific plate beneath the Eurasian

plate was the seismogenesis of the event. Figure 1.18 shows contours of shakingdamage percentage for

Japanese wooden houses, contours of uplift and subsidence, locations of tsunami, and other effects in

the most severely affected region [Hamada et al., 1992]. Seismic intensity on the Japan MeteorologicalAgency scale (JMA, see Chapter 4)is also indicated on the figure.

Damage was heaviest in the Yokohama and Tokyo urbanized areas, although the shore of Sagami Bay

and parts of the Boso peninsula also sustained heavy damage, a 3- to 6-m tsunami, and major geologic

effects, with maximum crustal uplift of 2 m. The death toll in Kanagawa and Tokyo prefectures was

97,000, including about 60,000 in Tokyo city. The total number of dead and missing reached about

143,000, with 104,000 people listed as injured. About 128,000 houses and buildings were destroyed,

another 126,000 heavily damaged, and as many as 447,000 lost to fire (Figures 1.19 and 1.20). Fire

accounted for the majority of houses destroyed in Tokyo, and about 50% of houses lost in Kanagawa

prefecture could be attributed to fire [Hamada et al., 1992].

The conflagration as a result of this fire is the largest peacetime conflagration in history, with combined

fire and earthquake fatalities exceeding those of the incendiary attacks on Tokyo in World War II, and

also probably exceeding the immediate fatalities in either of the atomic bombings of Hiroshima or

Nagasaki. The conflagration was initially a mass fire (Figure 1.21), although self-generated winds resulted

in large vortices or firestorm conditions in several locations, most notably at the Military Clothing

Depot in Honjo Ward, where many refugees had gathered. Most of them carried clothing, bedrolls, and

other flammables rescued from their homes, which served as a ready fuel source, and the engulfing flames

suffocated an estimated 40,000 people. The enormous conflagration was due to hot, dry, windy conditions

(although there had been some rain recently), combined with the time of the earthquake, just before

noon, when the population was preparing its lunch. Coal or charcoal cooking stoves were in use through-

out Tokyo and Yokohama for the noontime meal, and fires sprang up everywhere within moments of

the quake. Firespread was very rapid, due to high winds as well as lack of water for firefighting becauseof broken water mains [ASCE, 1929].

5Thomas J. Maher was a captain of the U.S. Coast and Geodetic Survey, and inspector-in-charge of the Survey's

San Francisco field station from 1928 to 1936. He retired in 1946, and died in June 1964.6 Another and more serious obstacle is the attitude of many persons, organizations, and commercial interests

toward earthquakes in general. The idea back of this false position for it is a false one is that earthquakes are

detrimental to the good repute of the West Coast, and that they are likely to keep away business and capital, and therefore

the less said about them the better. This theory has led to the deliberate suppression of news about earthquakes, and even

of the simple mention of them. Shortly after the earthquake of April 1906, there was a general disposition that almostamounted to concerted action for the purpose of suppressing all mention of that catastrophe. When efforts were made by

a few geologists to interest people and enterprises in the collection of information in regard to it, we were advised and

even urged over and over again to gather no such information, and above all not to publish it. Forget it,the less said,

the sooner mended,and there hasn't been any earthquake,were the sentiments we heard on all sides

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FIGURE 1.18 Map of distribution of damage, 1923 Kanto earthquake. (From Hamada, M., Wakamatsu, K., and Yasuda, S. 1992. Liquefa

during the 1923 Kanto Earthquake, in Case Studies of Liquefaction and Lifeline Performance during Past Earthquakes, Vol. I,Japanese Case

T.D., Eds., Technical report NCEER-920001, February, National Center for Earthquake Engineering Research, State University of New Yor

EX

Tsu

City

BoPre1%

10%

50%

Up

SuBreEle

Ob

+ 9

9

0


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1.2.2.3 1925: Santa Barbara; 1933: Long Beach Earthquakes

The M6.2 Santa Barbara earthquake occurred on June 29, 1925 and caused $8 million damage and 13

fatalities from an offshore shock in the Santa Barbara Channel, on an extension of the Mesa Fault or the

Santa Ynez system. On State Street, the principal business thoroughfare, few buildings escaped damage;

several collapsed. The shock occurred at 6:42 a.m., before many people had reported for work and when

streets were uncrowded, reducing death and injury.

The M6.3 Long Beach earthquake of March 10, 1933 had its epicenter offshore, southeast of Long

Beach, on the Newport-Inglewood fault, and caused $40 million property damage and 115 lives lost

(Figure 1.22). The major damage occurred in the thickly settled district from Long Beach to the industrial

section south of Los Angeles, where unfavorable geological conditions (made land, water-soaked allu-

vium) combined with much poor structural work to increase the damage. At Long Beach, buildings

collapsed, tanks fell through roofs, and houses displaced on foundations. School buildings were among

those structures most generally and severely damaged (Figure 1.23), and it was clear that a large numberof children would have been killed and injured had the earthquake occurred during school hours.

These two earthquakes are discussed not so much for the size or peculiarities of damage, but due to

advances in engineering and building code requirements instituted following these two events (see

Chapter 11,this volume, for a more detailed discussion of this aspect):

FIGURE 1.22 MMI isoseismal map, 1933 Long Beach earthquake. (From Stover, C.W. and Coffman, J.L. 1993.

Seismicity of the United States, 15681989(revised). U.S. Geological Survey Professional Paper 1527, U.S. Government

Printing Office, Washington, D.C.)

San Diego

Los Angeles

EXPLANATION

Epicenter

IntensityVIII

IV

II-III

MexicoUnitedStat

es

VI

II-III

VBIythe

ARIZONA

CALIFORNIA

VI

VII

VIII

FresnoLas Vegas

IV

NEVADA

UTAH

114116118120122

38

36

San Francisco

34

32

GulfofC

alifornia

PacificO

cean

1000

KILOMETERS

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the Pacific Fire Rating Bureau [Steinbrugge and Moran, 1954]. It claimed 12 lives and caused property

damage estimated at $60 million. It was unusual in that an aftershock (August 22, M5.8) actually caused

more damage in Bakersfield than the main shock, although the damage was to structures already some-

what damaged by the main shock.

The generally moderate damage in Bakersfield was confined mainly to isolated parapet failure. Cracks

formed in many brick buildings, and older school buildings were damaged somewhat. In contrast,

however, the Kern General Hospital was damaged heavily. Multistory steel and concrete structures

sustained minor damage, which commonly was confined to the first story. MMI XI was assigned to a

small area on the Southern Pacific Railroad southeast of Bealville. There, the earthquake cracked rein-

forced-concrete tunnels having walls 46 cm thick, shortened the distance between portals of two tunnels

about 2.5 m, and bent the rails into S-shaped curves. Reports of long-period wave effects from the

earthquake were widespread. Water splashed from swimming pools as far distant as the Los Angeles area,

where damage to tall buildings was nonstructural but extensive. Water also splashed in pressure tanks

on tops of buildings in San Francisco [Stover and Coffman,1993].The 1952 Kern County earthquake was investigated by a new generation of structural engineers and

earth scientists, who moved over the next several years to create the first edition of the Structural

Engineers Association of Californias Recommended Lateral Force Requirements, or Blue Book, which

FIGURE 1.24 Modified Mercalli Intensity map, 1952 Kern County earthquake. (FromStover, C.W. and Coffman,

J.L. 1993. Seismicity of the United States, 15681989(revised). U.S. Geological Survey Professional Paper 1527, U.S.

Government Printing Office, Washington, D.C.)

40

38

36

32

VII VII

VII

VII

Bakersfield

VI

V-VI

Los Angeles

Fresno

San Diego

Pacific

Ocean

V

IV

III

Las Vagas

34

ARIZONA

UnitedStatesMexico

IV-V

V-IVBishop

CaliforniaSan Francisco

Monterey

Oroville

NEVADA

IV

VIII

VII

I-IIIReno

V

IV

V-VI

124 122 120 118 116 114

UTAH

YumaEXPLANATION

EpicenterVIII Intensity 9

KILOMETERS

1000


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was the first uniform code for seismic areas in the United States [SEAOC, 1980]. This was a critical

development, as the Blue Book became the model for seismic requirements and building codes around

the world.

1.2.3.2 1960: May 22, Chile (Mw9.5)

On May 22, 1960, a Mw9.5 earthquake, the largest earthquake ever instrumentally recorded, occurred

in southern Chile. The series of earthquakes that followed ravaged southern Chile and ruptured over

a period of days a 1000-km section of the fault, one of the longest ruptures ever reported. The

number of fatalities associated with both the tsunami and the earthquake has been estimated between

490 and 5,700. Reportedly there were 3,000 injured, and initially there were 717 missing. The Chileangovernment estimated 2,000,000 people were left homeless and 58,622 houses were completely

destroyed. Damage (including tsunami damage) was more than U.S. $500 million. The main shock

set up a series of seismic sea waves (tsunamis) that not only was destructive along the coast of Chile

(Figures 1.25and 1.26), but that also caused numerous casualties and extensive property damage in

FIGURE 1.25 1960 Chile Mw9.5 earthquake. The ship

in the photo was wrecked by the tsunami on Isla Mocha

(north of Valdivia). Note the raised beach and landslides.

Large landslides and massive flows of earthen debris and

rock occurred on the island. The tsunami runup on Isla

Mocha was 25 m (more than 82 ft). (From NOAA/

NGDC, http://www.ngdc.noaa.gov/seg/hazard/slideset/

tsunamis.)

FIGURE 1.26 1960 ChileMw9.5 earthquake. The fish-

ing village of Queule (north of Valdivia and south of

Lebu) before and after the catastrophe of May 1960. The

bottom photo was taken after the land subsidence and

after the tsunami. The town was destroyed. The houses,

together with the remains of fishing boats and uprootedtrees, were washed as much as 2 km inland by a tsunami

4.5 m high. The sinking of the land also brought about

a permanent rise of the sea. The meandering creek bed

in the foreground has been changed into an estuary. The

trees that dot the river bank in the top photo are the only

ones that remain in the bottom photo. Also the linear

feature next to the solitary tree in the bottom photo can

be found in the top photo marked with smaller trees that

later disappeared in the wave. (From NOAA/NGDC,

http://www.ngdc.noaa.gov/seg/hazard/slideset/tsuna-

mis/.)

http://www.ngdc.noaa.gov/seg/hazard/slideset/tsunamis/http://www.ngdc.noaa.gov/seg/hazard/slideset/tsunamis/http://www.ngdc.noaa.gov/seg/hazard/slideset/tsunamis/http://www.ngdc.noaa.gov/seg/hazard/slideset/tsunamis/http://www.ngdc.noaa.gov/seg/hazard/slideset/tsunamis/http://www.ngdc.noaa.gov/seg/hazard/slideset/tsunamis/http://www.ngdc.noaa.gov/seg/hazard/slideset/tsunamis/http://www.ngdc.noaa.gov/seg/hazard/slideset/tsunamis/http://www.ngdc.noaa.gov/seg/hazard/slideset/tsunamis/http://www.ngdc.noaa.gov/seg/hazard/slideset/tsunamis/

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Hawaii and Japan, and that was noticeable along shorelines throughout the Pacific Ocean area. There

were several other geologic phenomena besides tsunamis associated with this event. Subsidence

caused by the earthquake produced local flooding and permanently altered the shorelines of much

of the area in Chile impacted by the earthquake. Landslides were common on Chilean hillsides. The

Puyehue volcano erupted 47 h after the main shock [NOAA/NGDC, n.d.].

1.2.4 First Turning PointThis section briefly describes salient points from selected earthquakes between 1964 and 1971, a period

that ended with a major change in the thinking of earthquake engineers and that, within a few years, led

to a National Earthquake Hazards Reduction Program in the United States, and heightened activity in

other countries.

1.2.4.1 1964: March 28, Alaska (Mw8.3)

This great earthquake and ensuing tsunami took 125 lives (tsunami 110, earthquake 15), and caused

about $311 million in property loss. Earthquake effects were heavy in many towns, including Anchorage,

Chitina, Glennallen, Homer, Hope, Kasilof, Kenai, Kodiak, Moose Pass, Portage, Seldovia, Seward, Ster-

ling, Valdez, Wasilla, and Whittier (Figure 1.27).Anchorage, about 120 km northwest of the epicenter, sustained the most severe damage to property.

About 30 blocks of dwellings and commercial buildings were damaged or destroyed in the downtown

area. The J.C. Penney Company building was damaged beyond repair (Figure 1.28); the Four Seasons

apartment building, a new six-story structure, collapsed (Figure 1.29); and many other multistory

FIGURE 1.27 MMI map, 1964 Alaska earthquake. (From NOAA/NGDC, http://www.ngdc.noaa.gov/seg/hazard/

slideset/earthquakes/7/7_slides.html.)

180 172 164 156 148 140 132 124

Arctic OceanBarrow

Inuvik

III-IV

V

VI

Fairbanks

Canada

Unite

dS

tates

ALASKAMayo

Anchorage

VII

VII-X

Pacific Ocean

Epicenter

EXPLANATION

Intensity 10X

Yakutat

Ketchika

n

Kodiak

Bering

Sea

USSR

United

State

s

Nome

Juneau

88

64

60

56

KILOMETERS

1000

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buildings were damaged heavily. The schools in Anchorage were heavily damaged. The Government Hill

Grade School, sitting astride a huge landslide, was almost a total loss. Anchorage High School and Denali

Grade School were damaged severely. Duration of the shock was estimated at 3 min.

Landslides in Anchorage caused heavy damage. Huge slides occurred in the downtown business section

(Figure 1.30), at Government Hill, and especially at Turnagain Heights (Figure 1.31), where an area of

about 130 acres was devasted by displacements that broke the ground into many deranged blocks that

were collapsed and tilted at all angles. This slide destroyed about 75 private homes. Water mains and gas,

sewer, telephone, and electrical systems were disrupted throughout the area.

The earthquake was accompanied by vertical displacement over an area of about 52,000 km 2. The

major area of uplift trended northeast from southern Kodiak Island to Prince William Sound and trended

FIGURE 1.28 This slide shows the five-story J.C. Penney building at 5th Avenue and Downing Street in Anchorage,

where two people died and one was injured. Concrete facing fell on automobiles in front of the building. Although

the building was approximately square, the arrangement of effective shear-resisting elements was quite asymmetrical,

consisting principally of the south and west walls that were constructed of poured concrete for the full building

height. The north and east sides of the building faced the street. The north side of the building had no shear wallbut was covered by a facade composed of 4-inch (10.2-cm) thick precast, nonstructural reinforced concrete panels.

The east wall, also covered with the precast panels, had poured-concrete shear walls between columns in the two

northerly bays and in the bottom three stories of the two southerly bays. The rotational displacement induced by

the earthquake apparently caused failure of this east wall shear-resistant element, the building became more suscep-

tible to rotational distortion, and the south and west shear walls failed. (From NOAA/NGDC, http://

www.ngdc.noaa.gov/seg/hazard/slideset/earthquakes/7/7_slides.html.)

FIGURE 1.29 The Four Seasons Apartments in Anchorage was a six-story, lift-slab reinforced concrete building that

crashed to the ground during the earthquake. The building was structurally complete but unoccupied at the time of

the earthquake. The main shear-resistant structural elements of the building, a poured-in-place, reinforced-concrete

stairwell and a combined elevator core and stairwell, fractured at the first floor and toppled over, and came to rest

on top of the rubble of all six floors and the roof. The concrete stairwell is in the center of the picture. (FromNOAA/

NGDC, http://www.ngdc.noaa.gov/seg/hazard/slideset/earthquakes/7/7_slides.html.)

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eastwest to the east of the sound. Vertical displacements ranged from about 11.5 m of uplift to 2.3 m

of subsidence relative to sea level. Off the southwest end of Montague Island, there was absolute vertical

displacement of about 13 to 15 m. Uplift also occurred along the extreme southeast coast of Kodiak

Island, Sitkalidak Island, and over part or all of Sitkinak Island. The zone of subsidence covered about

285,000 km2, including the north and west parts of Prince William Sound, the west part of the Chugach

Mountains, most of Kenai Peninsula, and almost all the Kodiak Island group.

This shock generated a tsunami that devastated many towns along the Gulf of Alaska (Figure 1.32),

and left serious damage at Alberni and Port Alberni, Canada, along the West Coast of the United States

(15 killed), and in Hawaii. The maximum wave height recorded was 67 m at Valdez Inlet. Seiche actionin rivers, lakes, bayous, and protected harbors and waterways along the Gulf Coast of Louisiana and Texas

caused minor damage. It was also recorded on tide gages in Cuba and Puerto Rico. This great earthquake

was felt over a large area of Alaska and in parts of western Yukon Territory and British Columbia, Canada

[Stover and Coffman, 1993].

FIGURE 1.30 This view of damage to Fourth Avenue buildings in downtown Anchorage shows the damage resulting

from the slide in this area. Before the earthquake, the sidewalk in front of the stores on the left, which are in the

graben, was at the level of the street on the right, which was not involved in the subsidence. The graben subsided

11 feet (3.3 m) in response to 14 feet (4.2 m) of horizontal movement of the slide block during the earthquake.

Lateral spreading produced a fan-shaped slide 1800 feet (545.5 m) across that covered about 36 acres (14.6 ha) andmoved a maximum of 17 feet (5.1 m). Movement on the landslide began after about 1 to 2 min of ground shaking

and stopped when the shaking stopped. (FromNOAA/NGDC, http://www.ngdc.noaa.gov/seg/hazard/slideset/earth-

quakes/7/7_slides.html.)

FIGURE 1.31 The Turnagain Heights landslide in Anchorage. Seventy-five homes twisted, slumped, or collapsed

when liquefaction of subsoils caused parts of the suburban bluff to move as much as 2000 feet (606 m) downward

toward the bay, forming a complex system of ridges and depressions. The slide developed because of a loss in strength

of the soils, particularly of lenses of sand, that underlay the slide. The motion involved the subsidence of large blocks

of soil, the lateral displacement of clay in a 25-foot (7.6-m) thick zone, and the simultaneous lateral translation of

the slide debris on liquefied sands and silts. (From NOAA/NGDC, http://www.ngdc.noaa.gov/seg/hazard/slideset/

earthquakes/7/7_slides.html.)

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The Alaska earthquake had two significant influences: (1) its truly remarkable size, area affected, and

geologic effects greatly stimulated the earth sciences in the United States, and led to a major documen-

tation of the event [U.S. Coast and Geodetic Survey, 1967]; and (2) the impacts on modern structures,

such as the J.C. Penney and Four Seasons Apartment buildings, alarmed structural engineers and started

a thought process that would lead to major building code changes within a decade.

1.2.4.2 1964: June 16, Niigata, Japan (M7.5)

The city of Niigata, on the Japan Sea coast of the island of Honshu, Japan, was struck by a M7.5 earthquake

at 1:25 p.m, June 16, 1964, resulting in widespread damage (Figure 1.33) (seeChapter 4for an explanation

of the JMA intensity scale). Many buildings, bridges, quay walls, and lifeline systems suffered severe

damage, and it was fortunate that only 26 persons were killed. The real significance of this event was the

technical investigation and identification of the cause of some remarkable building failures, which were

caused by liquefaction. Being a natural phenomenon, liquefaction had occurred in most larger earth-

quakes since time immemorial (seeFigure 1.8,for example), but had not been specifically identified and

investigated.

At the Kawagishi-cho apartments in Niigata city, liquefaction occurred, resulting in the overturning

collapse of the buildings (Figure 1.34). Note the quality of the construction; even though overturned,

these buildings remained intact. Koizumi [1965] identified liquefaction and its cause and, combined withthe major examples of liquefaction observed in Alaska earlier the same year, this led to a major research

effort into the analysis and mitigation of liquefaction over the next several decades.

1.2.4.3 1971: February 9, San Fernando, CA (M6.5)

This destructive earthquake occurred in a sparsely populated area of the San Gabriel Mountains, near

San Fernando, killing 65, injuring more than 2000, and causing property damage estimated at $505

million [NOAA, 1973] (Figure 1.35). The earthquake created a zone of discontinuous surface faulting,

named the San Fernando fault zone, which partly follows the boundary between the San Gabriel Moun-

tains and the San Fernando-Tujunga Valleys and partly transects the northern salient of the San Fernando

Valley. This latter zone of tectonic ruptures was associated with some of the heaviest property damage

sustained in the region. Within the entire length of the surface faulting, which extended roughly eastwest

for about 15 km, the maximum vertical offset measured on a single scarp was about 1 m, the maximum

lateral offset about 1 m, and the maximum shortening (thrust component) about 0.9 m.

FIGURE 1.32 This photo was taken at Seward at the north end of Resurrection Bay, showing an overturned ship,

a demolished Texaco chemical truck, and a torn-up dock strewn with logs and scrap metal after the tsunamis.

The waves left a shambles of houses and boats in the lagoon area, some still looking relatively undamaged and

some almost completely battered. The total damage to port and harbor facilities at Seward was estimated at more

than $15,000. Most of this damage was the result of the tsunamis. Eleven persons lost their lives due to the seawaves at Seward. (From NOAA/NGDC, http://www.ngdc.noaa.gov/seg/hazard/slideset/earthquakes/7/

7_slides.html.)

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FIGURE 1.33 Japan Meteorological Agency intensity map of 1964 Niigata, Japan, earthquake. (From Japan Mete-

orological Agency. With permission.)

FIGURE 1.34 1964 Niigata earthquake, over-

turning of apartment buildings, Kawagishi-cho,

Niigata. (FromNOAA/NGDC, available online at

http://www.ngdc.noaa.gov/seg/hazard/slideset/

earthquakes/.)

Aikawa

Wajima

Akita

Sakata

5

5

V

IV

44

Niigata

YamagataSendai

Wakamatsu

Shirakawa

5

4

4 4

4 4

5

Miyako

Morioka

Ofunato

3

3

Onahama

Nagano Maebashi

Matsushiro

Takayama

Iida

Tokyo

Kofu

Mito

Kakioka

Choshi

Yokohama

TomizakiShizuoka

4

4

4

4

3

33

33

3

3

22

2 2

2

2

3

3

3

3

11

1

I

II

III1

3

Fukui

Kanazawa

Cape Omaezaki

4

IV

V

Aomori Hachinohe2

1

N

II

III

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The most spectacular damage included the destruction of major structures at the Olive View and the

Veterans Administration Hospitals, and the collapse of freeway overpasses (Figure 1.36). The newly built

earthquake-resistant buildings at the Olive View Hospital in Sylmar were destroyed; four five-story wings

pulled away from the main building and three stair towers toppled(Figure 1.37). Although newly built

and complying with the building code, the buildings columns lacked confinement due to widely spaced

lateral ties. Older, unreinforced masonry buildings collapsed at the Veterans Administration Hospital at

San Fernando, killing 49 people (Figure 1.38). Many older buildings in the Alhambra, Beverly Hills,

Burbank, and Glendale areas were damaged beyond repair, and thousands of houses and chimneys were

damaged in the region (Figure 1.39). A large number of one-story commercial buildings, termed tilt-ups,

were found to have a common design flaw, involving the roof-wall connection putting the wood ledger

in cross-grain bending, which is discussed inChapter 14of this volume.

Public utilities and facilities of all kinds were damaged, both above and below ground. Severe ground

fracturing and landslides were responsible for extensive damage in areas where faulting was not observed.

The most damaging landslide occurred in the Upper Lake area of Van Norman Lakes, where highway

overpasses, railroads, pipelines, and almost all structures in the path of the slide were damaged severely.

Several overpasses collapsed. Two dams were damaged severely (Lower Van Norman Dam and Pacoima

Dam) (Figure 1.40), and three others sustained minor damage. Lower Van Norman Dam came very close

to overtopping, which would have resulted in a sudden release of the impounded water and probable

mass casualties for the 80,000 people living below the dam [Stover and Coffman, 1993].

The impact of the San Fernando earthquake on engineers was out of all proportion to the numberkilled, or even the monetary costs. Engineers were shocked to observe that modern structures, such as

Olive View Hospital, Van Norman Dam, highway bridges, and tilt-up buildings, were failing under a

moderate-sized earthquake. Of note also was the recording during the event of about 100 strong ground

motion records, which effectively doubled the number of new records then in existence!

FIGURE 1.35 Modified Mercalli Intensity map of 1971 San Fernando earthquake. (From NOAA/NGDC, available

online athttp://neic.usgs.gov/neis/eqlists/USA/1971_02_09_iso.html.)

38

36

34

32

122 120 118 116 114

Fresno

NEVADA UTAH

Las Vagas

Barstow

ARIZONA

California

Los Angeles

Paci

fic

Ocean

Santa Maria

I-IV

V

II-IV

II-IV

VII-XI VIIVI

UnitedStates

Mexico Yuma

Monterey

Stockton

San DiegoEXPLANATION

Epicenter1X Intensity 11KILOMETERS

1000

Tonopah

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FIGURE 1.36 The I-5 (Golden State) and I-210 (Foothills) Freeway Exchange. There was damage to both roadway

and structures on the completed portion of this freeway, from its intersection with Route 5 to the Maclay Street

separation. Throughout this section, the freeway appeared to settle on a somewhat uniform grade line. The settling

was especially noticeable at the bridges, where it varied from 6 to 24 inches. Pavement was buckled and broken for

several hundred feet on each side of the damaged structures. Structural damage varied, from minor damage to wing

walls and slope paving, to rotation and settlement of abutments, splaying and cracking of columns, displacement of

wing walls, and contortion of the sides of fills. Street sections beneath the various undercrossings suffered damage

to curbs, sidewalks, slope paving, and roadway sections. (Photo: E.V. Leyendecker, U.S. Geological Survey. From

NOAA/NGDC, available online athttp://www.ngdc.noaa.gov/seg/hazard/slideset/earthquakes/20/20_slides.html.)

FIGURE 1.37 Damage sustained in the 1971 San Fernando, California, earthquake. (A) This building, known as

the Medical Treatment and Care Building (in the Olive View Hospital complex) was completed in 1970 at a cost of

$25 million. The four towers containing the stairs and day-room areas were built to be structurally separated four

inches from the main building. The three towers that failed were supported by concrete columns. When these columns

failed, the towers overturned. Note that the base of the tower in this photo has fallen in the basement. After the

shock, the building leaned as much as 2 feet in a northerly direction with nearly all of this drift in the first story.

Note also the broken columns on the first floor. The first story nearly collapsed, and the building was ultimately

demolished. The structure was located in a band that incurred heavy damage during the 1971 earthquake. (Photo:

E.V. Leyendecker, U.S. Geological Survey.) (B) Close-up of first-story column failure at Olive View Hospital. The

column was located at the west end of Wing B on the first story of the five-story hospital. This is a typical first-story

tied corner column, and the damage is characteristic of column damage found on the first floor in all wings of thehospital. These corner columns were square with a corner notch out, giving the appearance of a thick L-shaped

column. Note the broken ties, the spacing of the ties, and the bent rebar. The building was laterally displaced about

2 feet to the north in the earthquake. (Photo: E.V. Leyendecker, U.S. Geological Survey. From NOAA/NGDC, available

online at http://www.ngdc.noaa.gov/seg/hazard/slideset/earthquakes/20/20_slides.html.) Shown as Color Figure 1.37.

(A) (B)

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1.2.4.4 New Directions

The 1971 San Fernando earthquake, coming within a few years of the 1964 Alaska, 1964 Niigata (Japan),

1967 Caracas (Venezuela), and 1968 Tokachi-oki (Japan) earthquakes (the latter two events are not

discussed here), brought a realization among geotechnical and structural engineers that major changes

were needed in the building codes, as well as that other earthquake mitigation measures were requiredto deal with existing structures. During the 1970s:

The Uniform Building Code was revised in the 1973 and 1976 editions to increase lateral force

requirements, correct the defective detail for roof-wall connections in tilt-up and similar buildings,

FIGURE 1.38 Aerial view of the damage to the SanFernando Veterans Administration Hospital and com-plex. This complex was located in the band of accentu-ated damage found along the base of the San GabrielMountains. The collapsed structure was built in 1926,

before earthquake building codes were in effect. Forty-seven of the 65 deaths attributed to the earthquakeoccurred as a result of the collapse of this structure.(Photo:E.V. Leyendecker, U.S. Geological Survey. FromN O AA/ N G D C, av a i l ab le o n l in e a t h t t p : / /www.ngdc.noaa.gov/seg/hazard/slideset/earthquakes/20/20_slides.html.)

FIGURE 1.39 A home in Crestview Park on AlmetzStreet. More than 700 dwellings were evacuated anddeclared unsafe after the San Fernando earthquake.(Photo: E.V. Leyendecker, U.S. Geological Survey. FromN O AA/ N G D C, av a i l ab le o n l in e a t h t t p : / /www.ngdc.noaa.gov/seg/hazard/slideset/earthquakes/20/20_slides.html.)

FIGURE 1.40 Van Norman Dam (Lower San FernandoDam). For a length of about 1800 feet, the embankment(including the parapet wall, dam crest, most of theupstream slope, and a portion of the downstream slope)slid into the reservoir. A loss of about 30 feet of damheight resulted when as much as 800,000 cubic yards ofdam embankment was displaced into the reservoir. Thismaterial slid when liquefaction of the hydraulic fill onthe upstream side of the embankment occurred. The damwas about half full at the time. Eighty-thousand peopleliving downstream of the dam were immediately orderedto evacuate, and steps were taken to lower the water level

in the reservoir as rapidly as possible. The Los AngelesDam was constructed to replace the Van Norman Reser-voir. (Photo: E.V. Leyendecker, U.S. Geological Survey.From NOAA/NGDC, available online at http://www.ngdc.noaa.gov/seg/hazard/slideset/earthquakes/20/20_slides.html.)

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and require adequate lateral spacing in reinforced concrete columns (see Hamburger,Chapter 11,

this volume).

A major reshaping of building code earthquake provisions was undertaken [Applied Technology

Council, 1978].

Investigation of liquefaction, which was the root of the failure of the Lower Van Norman Dam,had begun following the 1964 events, and practical engineering tools soon emerged to analyze the

potential for liquefaction (see Brandes,Chapter 7,this volume).

The failures of power, water, and other infrastructure led to the birth of lifeline earthquake

engineering (see Eguchi, Chapter 22, this volume) to address seismic vulnerabilities in urban

infrastructure.

The United States instituted a national dam-safety program (see Bureau, Chapter 26,this volume).

In 1977, the National Earthquake Hazards Reduction Act of 1977, Public Law 95124, was passed,

culminating thinking that had begun prior to the 1964 Alaska earthquake and evolved into a series

of studies and high-level reports [see EERI, 1999; also available online at http://quake.wr.usgs.gov/

research/history/wallace-VI.html] leading to the passage of the NEHRP.

1.2.5 Second Turning Point

1.2.5.1 1985: September 19, Michoacan, Mexico (M7.9)

The earthquake occurred in the state of Michoacan, Mexico, on Thursday, September 19, 1985 at 7:18 a.m.

local time. The epicenter was approximately 40 miles west of El Infiernillo Dam on the Balsas River, near

the town of Lazaro Cardenas on the Pacific coast. The next day, an aftershock of magnitude 7.5 struck

approximately 70 miles to the southwest, 15 miles north of Zihuatenejo, in the state of Guerrero, at 7:37

p.m. local time. At least 9,500 people were killed, about 30,000 were injured, more than 100,000 people

were left homeless, and severe damage was caused in parts of Mexico City and in several states of central

Mexico. It is widely rumored in Mexico that the death toll from this earthquake may have been as high

as 35,000. It is estimated that the quake seriously affected an area of approximately 825,000 km 2, caused

between U.S. $3 and $4 billion of damage, and was felt by almost 20 million people. Four hundred twelve

buildings collapsed and another 3,124 were seriously damaged in Mexico City. About 60% of the buildings

were destroyed at Ciudad Guzman, Jalisco. Damage also occurred in the states of Colima, Guerrero,

Mexico, Michoacan, Morelos, parts of Veracruz, and in other areas of Jalisco.

This event was extremely remarkable and received wide attention because the epicenter was about 400

km from central Mexico City, where the greatest loss of life occurred. Earthquakes do not usually cause

significant damage at this distance, and the major damage in Mexico City was due to an unfortunate

combination of circumstances:

1. It was a large, distant event, resulting in higher frequencies being largely attenuated, with peak

ground accelerations (PGA) of only 0.03 to 0.04gon firm soils in Mexico City (CU station, see

Figure 1.41), but with lower frequencies (longer periods) still having significant energy when the

seismic waves reached Mexico City.

2. The Valle de Mexico has unusual geology. It is an enclosed basin, surrounded by active volcanoes,

in which all drainage is trapped (a shallow lake still existed at the time of the Spanish Conquest,

ca. 1500). There are three zones: (1) a foothill zone consisting of firm volcanic deposits mostly

west of downtown; (2) a lake zone consisting of ash from the volcanoes which has fallen on the

basin for thousands of years and slowly settled (pluviated) in the central lake of the basin, formed

by the runoff trapped in the basin. The center of the basin is therefore a very deep, soft deposit

of saturated ash; and (3) intermediate between these two zones is a transition zone. The soft ash-water deposits in the lake zone are very soft, but elastic over a large strain range, with a natural

period of about 2 sec.

3. The oldest part of the city, and many of the high rises, are in the Lake zone. Settlement of buildings

built in this zone is extreme, if not properly founded. A rule-of-thumb is that the natural period

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of buildings, T, = 0.1N, whereNis the number of stories, i.e., a 10-story building normally has a

period of about 1 sec, a 20-story building 2 sec, etc.8

4. The long period motion from the large distant event therefore tuned in,i.e., matched the period

(of about 2 sec) on the deep, soft deposits of the Lake zone, resulting in resonance of the input

ground motion, with unusually strong amplification; PGA of 0.18 g was recorded at the SCT

station near the edge of the Transition-Lake zones (seeFigure 1.41).

5. On the soft soils the amplified ground motions with response spectra (for an explanation of

response spectra, seeChapter 4)tuned in on buildings with periods of about 1.0 to 1.5 sec (i.e.,

10- to 15-story buildings). As these buildings were damaged and weakened, their period soft-

ened, i.e., became longer, and thus moved toward the peak amplification region at 2 sec in the

already amplified response spectra, resulting in a double resonance. As buildings in the 10- to

15-story range weakened, they were being more strongly loaded to collapse. As they weakened,

taller buildings (longer periods) were moving into the downhill side of Figure 1.41, and thus

shedding load.

The result was that damage was highly selective and occurred most in buildings in the 10- to 15-story

range. Figure 1.42shows results of a survey by teachers and students at the Autonomous University of

Mexico [UNAM, 1985], in which it can be seen that 9- to 12-story buildings were found to be most

heavily damaged.

The damage was truly devastating.Figure 1.43shows the Pino Suarez 23-story building,9the tallest

building to collapse for any reason prior to September 11, 2001. In all three 23-story towers, the columns

were welded box columns that buckled at the fourth floor, leading to a story mechanism and collapse

[Osteraas and Krawinkler, 1989] of one of the 23-story towers onto the southern 16-story tower, both

towers finally collapsing into the street.Figure 1.43Ashows the elevation of the complex: three central

FIGURE 1.41 Response spectra (5% damped), Mexico City CU (firm) and SCT (soft) stations, September 19, 1985

Michoacan earthquake.

8Specific building data for Mexico City buildings indicated the relationship was T = 0.12 + 0.086N[Scawthorn

et al., 1986).9The Pino Suarez complex consisted of a 2-story, reinforced concrete base building supporting three 21-story and

two 14-story, steel-framed towers (one 14-story at the north and one at the south end of the row of towers). The

buildings are sometimes referred to as being 21 stories tall [e.g., Osteraas and Krawinkler, 1989], when in fact they

were 23 stories above the ground (21 stories + 2-story base).

1.0

0.8

0.6

0.4

0.2

0.0 1 2

T (Seconds)

3 4

C =V/W = 5% Response Spectrum

EW ComponetZat SCT

NS Componet at SCT

EW Componet at CU

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23-story towers with two 16-story towers each at each end, all steel framed; Figure 1.43B shows the

collapsed towers; Figure 1.43B shows the remaining towers, with the southernmost one with cladding

removed, exposing the steel framing;Figures 1.43Cand Dshow the buckled box column (note the weldedC-section around the buckle, placed following the earthquake to stabilize the buildings). In both remain-

ing 23-story towers, the pattern of buckled columns at the fourth floor was remarkably consistent.

Figure 1.44shows the collapse of the 14-story reinforced concrete Nuevo Leon building in the Tlatelolco

complex. As can be seen inFigure 1.44A, the building had an unusual X-bracing scheme in the transverse

direction. Inspection indicated (1) columns sheared in the longitudinal direction at the sky-lobbies, and

(2) failed X-bracing connections in the transverse direction. Figure 1.45shows examples of other damage

in this event.

Figure 1.46shows the Hotel Regis, which partially collapsed in the earthquake. An immediate ignition

quickly engulfed the building and trapped occupants, and spread over the next 24 hours to all other

buildings in the block, including several important government buildings.

The Mexico City event was perhaps the first earthquake, with the exception of the 1967 Caracas,

Venezuela, event (not discussed here), to cause the collapse of numerous major modern high-rise build-

ings. This was largely due to it being the first earthquake (Caracas excepted) to strongly shake major,

modern high-rise buildings.

1.2.5.2 1988: December 7, Armenia (M7.0)

On December 7, 1988, at 11:41 a.m. local time, a M7.0 earthquake struck northwest Armenia, at the time

a Soviet republic with 3.5 million people. Armenia occupies approximately 30,000 km2in the southern

Caucasus Mountains, generally considered the boundary between Europe and Asia (Figure 1.47). The

event caused catastrophic damage that resulted in 25,000 deaths and $16 billion loss in a 400-km 2

epicentral region occupied by approximately 700,000 people. Damage and several deaths also occurredin the Kars region of Turkey, 80 km southwest of the earthquakes epicenter.

The Armenian earthquake was a disaster of modern concrete buildings designed and constructed in

the 1970s, not of old, unreinforced stone masonry buildings, the predominant type of construction.

FIGURE 1.42 Damage survey. (From Scawthorn, C. et al. 1986, after UNAM, 1985. With permission.)

N = 1 to 2 3 to5 6 to 8

No. FLOORS

DAMAGEDBLDGS(%)

9 to 12 > 12

20

19

18

1716

1514

13

12

11

10

98

7

6

5

43

2

1

0

DAMAGED BLDGS. VS. HGT, UNAM SURVEY

Central Mexico City, 19 Sept 1966


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Faced with a housing shortage and a wave of urbanization in the 1970s, Soviet urban planners relaxed

standards for new multistory buildings and raised the height limit from five stories to nine. Failure of

these new buildings claimed the most lives. When these buildings collapsed, they fell straight down, either

crushing occupants in the compact piles of rubble or suffocating them. In Spitak, there were no undam-

aged buildings because of the strong epicentral shaking and the shallow (15 km) depth (Figure 1.48). In

Leninakan (now called Gyumri), approximately 80% of the building stock was damaged, with many

schools, hospitals, apartment buildings, and factories collapsing (Figure 1.49). The predominant building

type (unreinforced stone masonry bearing-wall construction) performed poorly overall, although most

low-rise unreinforced masonry buildings performed well. Nine-story precast, nonductile concrete frame

buildings performed poorly, with less than 12 of the more than 50 buildings remaining standing after

the earthquake. In contrast, a group of nine-story buildings having precast concrete wall and floor panels

performed well. Of two lift-slab buildings, a 10-story collapsed and a 16-story (the tallest) exhibited

severe torsion effects and heavy damage to the first floor.

FIGURE 1.43 Pino Suarez collapse, September 19, 1985 Mexico City earthquake. (A) Collapsed 23-story and 16-

story Pino Suarez towers. (Photo: E.V. Leyendecker. NOAA/NGDC.) (B) Elevation of two remaining 23-story and

one remaining 16-story tower, showing framing. (C) Buckled box column, Pino Suarez tower. (D) Close-up of buckled

box column, Pino Suarez tower. (Photos B, C, D: C. Scawthorn.) Shown as Color Figure 1.43.

(A) (B)

(C) (D)


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FIGURE 1.45 (CONTINUED)

(C)

(E)

(G)

(D)

(F)

(H)

(I)


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Both the 1985 Mexico City and 1988 Armenia events were now raising serious questions about the

safety of high-rise buildings.

1.2.5.3 1989: October 17, Loma

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