Lecture 22 23

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Earth Processes:Earthquakes

Dr. K. Vijaya Kumar

School of Earth SciencesSRTM University, Nanded 431 606Maharashtra, INDIA

(E-mail: [email protected])

Lecture 22 and 23

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Global Earthquake Locations

At the boundaries between plates, friction causes them to

stick together. When built up energy causes them to break,

earthquakes occur

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Plate Boundaries and Earthquakes

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Where do earthquakes form?

Figure showing the tectonic setting of earthquakes

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Earthquakes

Shaking of earth due to movement of rocks along a fault.Rocks under stress accumulate strain energy over time.When stress exceeds strength of rocks, rock breaks.Strain energy is released as seismic waves. The longer thatenergy is stored up and is maintained without release, themore likely that a strong earthquake will occur.

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Earthquakes are the manifestations of sudden release of strain energy

accumulated in the rocks over extensive periods of time

in the upper part of the Earth.

Seismology (derived from Greek word Seismos meaning

Earthquake and Logos meaning science) is the science ofEarthquakes and related phenomena

Aftershock

An earthquake that follows a large magnitude earthquake called,

main shock and originates in or around the rupture zone of the

main shock. Generally, major earthquakes are followed by a

number of aftershocks, which show a decreasing trend in

magnitude and frequency with time.

Seismograph/ Seismogram

Seismograph is an instrument that records the ground motions.

Seismogram is a continuous written record of an earthquake

recorded by a seismograph.

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Epicentre:

It is the point on the surface of the earth, vertically above

the place of origin (hypocentre) of an earthquake.

This point is expressed by its geographical Coordinates

in terms of latitude and longitude.

Hypocentre or Focus:

It is the point within the earth, from where seismic wavesoriginate. Focal depth is the vertical distance between

the Hypocentre (Focus) and Epicentre.

Magnitude:

It is a quantity to measure the size of an earthquake and is

independent of the place of the observation.

Intensity refers to the amount of damage done in an

earthquake and is dependent on the place of observation

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Tsunami

A system of gravity waves formed in the sea due to large

scale disturbance of sea level over a short duration of time.

Tsunamis are caused by earthquakes under the sea bottom,submarine volcanic eruptions, displacement of submarine

sediments, coastal landslides and meteor impact. However, not all

coastal earthquakes produce Tsunamis.

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Focus and Epicenter of Earthquake

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NATURE OF EARTHQUAKES

1) Foreshocks

2) Main shock

3) Aftershocks

4) Earthquake Swarm

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CLASSIFICATION DISTANCE

1) Teleseismic Earthquake > 1000 km2) Regional Earthquake > 500 km

3) Local Earthquake < 500 km

TYPES OF EARTHQUAKES

1) Tectonic Earthquake

2) Volcanic Earthquake

3) Collapse Earthquake

4) Explosion Earthquake

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Types of seismic waves1. Body waves -- travel through interior2. Surface waves -- travel on surface of earth

Specific Body WavesPrimary or "P" Waves: Primary waves Highest velocityCauses compression and expansion in direction of wave travel.Secondary or "S" Waves: Secondary or shear waves

Slower than P waves but faster than surface waves.Causes shearing of rock perpendicular to direction of wavepropagationCannot travel through liquids

Surface Waves or "Love" (L) WavesCause vertical & horizontal shakingTravel exclusively along surface of earth

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Primary or PWave

Secondary orS Wave

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Seismic Waves

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Time-Travel Curve

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Seismographs

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Seismogram Printout

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Determining the location of an earthquakeFirst, distance to earthquake is determined.1. Seismographsrecord seismic waves

2. From seismograph record called the seismogram, measure time delaybetween P & S wave arrival

3. Use travel time curve to determine distance to earthquake as functionof P-S time delay

Now we know distance waves traveled, but we don't know the direction fromwhich they came.

We must repeat the activity for each of at least three (3) stations totriangulate a point (epicenter of quake).

Plot a circle around seismograph location; radius of circle is the distance to thequake.

Quake occurred somewhere along that circle.

Do the same thing for at least 3 seismograph stations; circles intersect atepicenter. Thus, point is triangulated and epicenter is located.

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Triangulation of 3stations to locateearthquake

epicenter

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Earthquake Magnitude

M5

M6

M7

Magnitude-- measure of energy released duringearthquake.

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Richter Magnitude Scale

Distance S P Magnitude Amplitude

km sec ML mm

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Determining the magnitude of an earthquakeMagnitude-- measure of energy released during earthquake.There are several different ways to measure magnitude.Most common magnitude measure is Richter Magnitude, named for the

renowned seismologist, Charles Richter.

Richter Magnitude Measure amplitude of largest S wave on seismograph record. Take into account distance between seismograph & epicenter.

Richter Scale Logarithmic numerical (NOT a physical) scale Increasing one whole unit on Richter Scale represents 10 times greater

magnitude. Going up one whole unit on Richter Scale represents about a 30 times

greater release of energy.

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The Richter magnitudes are based on a logarithmic

scale (base 10). What this means is that for each

whole number you go up on the Richter scale, the

amplitude of the ground motion recorded by a

seismograph goes up ten times. Using this scale, a

magnitude 5 earthquake would result in ten times the

level of ground shaking as a magnitude 4 earthquake(and 32 times as much energy would be released). A

magnitude 1 seismic wave releases as much energy

as blowing up 6 ounces of TNT. A magnitude 8

earthquake releases as much energy as detonating 6million tons of TNT.

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Earthquake Magnitude Scale

Magnitude Earthquake Effects Estimated Number

Each Year

2.5 or less

Usually not felt, but can

be recorded by

seismograph.

900,000

2.5 to 5.4Often felt, but only

causes minor damage.30,000

5.5 to 6.0Slight damage tobuildings and other

structures.

500

6.1 to 6.9

May cause a lot of

damage in very

populated areas.

100

7.0 to 7.9Major earthquake.

Serious damage.20

8.0 or greater

Great earthquake. Can

totally destroy

communities near the

epicenter.

One every 5 to 10 years

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Earthquake Magnitude Classes

Earthquakes are also classified in categories ranging from

minor to great, depending on their magnitude.

Class Magnitude

Great 8 or more

Major 7 - 7.9

Strong 6 - 6.9

Moderate 5 - 5.9

Light 4 - 4.9

Minor 3 -3.9

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EARTHQUAKE INTENSITY

Rossi-Forel Intensity Scale (I X)

Modified Mercalli (MM) Intensity Scale

(1956 version), (I XII)

Medvedev-Sponheuer-Karnik (MSK) Intensity Scale(1992 Version), (I XII)

Isoseismals

Isoseismals are the curved lines joining the localities of same intensity.

Intensity refers to the amount of damage done in anearthquakeMercalli Scale is used to express damage

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Magnitude / Intensity Comparison

Magnitude and Intensity measuredifferent characteristics of earthquakes.

Magnitude measures the energy released

at the source of the earthquake.

Magnitude is determined frommeasurements on seismographs.

Intensity measures the strength of

shaking produced by the earthquake at acertain location. Intensity is determined

from effects on people, human structures,

and the natural environment.

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Magnitude Typical Maximum

Modified Mercalli

Intensity

1.0 - 3.0 I

3.0 - 3.9 II - III

4.0 - 4.9 IV - V

5.0 - 5.9 VI - VII

6.0 - 6.9 VII - IX

7.0 and higher VIII or higher

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Abbreviated Modified Mercalli Intensity Scale

I. Not felt except by a very few under especially favorable conditions.

II. Felt only by a few persons at rest, especially on upper floors of

buildings.

III. Felt quite noticeably by persons indoors, especially on upper floors ofbuildings. Many people do not recognize it as an earthquake. Standing

motor cars may rock slightly. Vibrations similar to the passing of a truck.

Duration estimated.

IV. Felt indoors by many, outdoors by few during the day. At night, some

awakened. Dishes, windows, doors disturbed; walls make cracking sound.Sensation like heavy truck striking building. Standing motor cars rocked

noticeably.

V. Felt by nearly everyone; many awakened. Some dishes, windows

broken. Unstable objects overturned. Pendulum clocks may stop.

VI. Felt by all, many frightened. Some heavy furniture moved; a fewinstances of fallen plaster. Damage slight.

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VII. Damage negligible in buildings of good design and construction;

slight to moderate in well-built ordinary structures; considerable

damage in poorly built or badly designed structures; some chimneys

broken.VIII. Damage slight in specially designed structures; considerable

damage in ordinary substantial buildings with partial collapse. Damage

great in poorly built structures. Fall of chimneys, factory stacks,

columns, monuments, walls. Heavy furniture overturned.

IX. Damage considerable in specially designed structures; well-

designed frame structures thrown out of plumb. Damage great in

substantial buildings, with partial collapse. Buildings shifted off

foundations.

X. Some well-built wooden structures destroyed; most masonry and

frame structures destroyed with foundations. Rails bent.

XI. Few, if any (masonry) structures remain standing. Bridgesdestroyed. Rails bent greatly.

XII. Damage total. Lines of sight and level are distorted. Objects thrown

into the air.

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EARTHQUAKE ENERGY

log E = 12 + 1.8 ML

log E = 5.8 + 2.4mb

log E = 11.4 + 1.5Ms

1.0 10.0 times about 32 times0.5 3.2 times about 5.5 times

0.3 2.0 times about 3 times

0.1 1.3 times about 1.4 times

Magnitude Ground Motion Energy

Magnitude versus ground motion and ener

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the big one

A Magnitude 8 (M8)

earthquake is much bigger

than a M7 earthquake:

Roughly 10x greater

displacements

Roughly 30x more energy

released

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Bigger Faults Make Bigger Earthquakes

1

10

100

1000

5.5 6 6.5 7 7.5Magnitude

Kilometers

8

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Bigger Earthquakes Last a Longer Time

1

10

100

5.5 6 6.5 7 7.5 8

Magnitude

Second

s

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EARTHQUAKE MAGNITUDE FREQUENCY AND ENERGY
http://en.wikipedia.org/wiki/File:Graph_of_largest_earthquakes_1906-2005.png

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EARTHQUAKE MAGNITUDE, FREQUENCY AND ENERGY

One of the largest earthquakes since seismometer invented ~ 1900

Stein & Wysession after IRIS

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LIST OF SOME SIGNIFICANT EARTHQUAKES IN INDIA

AND ITS NEIGHBOURHOOD

DATE EPICENTRE LOCATION MAGNITUDE

Lat (Deg.N)Lat

(Deg.E)

1819 JUN 16 23.6 68.6KUTCH,

GUJARAT8.0

1869 JAN 10 25 93

NEAR

CACHAR,

ASSAM

7.5

1885 MAY 30 34.1 74.6 SOPOR, J&K 7.0

1897 JUN 12 26 91SHILLONG

PLATEAU8.7

1905 APR 04 32.3 76.3 KANGRA,H.P

8.0

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1918 JUL 08 24.5 91.0SRIMANGAL,

ASSAM

7.6

1930 JUL 02 25.8 90.2DHUBRI,

ASSAM7.1

1934 JAN 15 26.6 86.8BIHAR-

NEPALBORDER8.3

1941 JUN 26 12.4 92.5ANDAMAN

ISLANDS8.1

1943 OCT 23 26.8 94.0 ASSAM 7.2

1950 AUG 15 28.5 96.7

ARUNACHAL

PRADESH-

CHINA BORDER

8.5

1956 JUL 21 23.3 70.0ANJAR,

GUJARAT7.0

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1967 DEC 10 17.37 73.75KOYNA,

MAHARASHTRA6.5

1975 JAN 19 32.38 78.49 KINNAUR, HP 6.2

1988 AUG 06 25.13 95.15

MANIPUR-

MYANMAR

BORDER

6.6

1988 AUG 21 26.72 86.63BIHAR-NEPAL

BORDER6.4

1991 OCT 20 30.75 78.86 Uttarakhasi, UP 6.6

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1993 SEP 30 18.07 76.62Latur/Killari

Maharashtra6.3

1997 MAY 22 23.08 80.06 Jabalpur, MP 6.0

1999 MAR 29 30.41 79.42Chamoli District,

UP6.8

2001 JAN 26 23.40 70.28 BHUJ , GUJARAT 7.7

2004 DEC 26 03.34 96.13OFF WEST COAST

OF SUMATRA9.3

2005 OCT 08 34.49 73.15 PAKISTAN 7.6

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Date Location Name Magnitude

0

May 22, 1960 Valdivia, Chile 1960 Valdiviaearthquake

9.5

March 27, 1964Prince William

Sound, Alaska, USA

1964 Alaska

earthquake9.2

December 26, 2004Indian Ocean,

Sumatra, Indonesia

2004 Indian Ocean

earthquake9.19.3

November 4, 1952Kamchatka, Russia

(then USSR)

1952 Kamchatka

earthquakes9.0

March 11, 2011

Pacific Ocean,

Thoku region,

Japan

2011 Thoku

earthquake9.0

November 25, 1833 Sumatra, Indonesia1833 Sumatra

earthquake8.89.2 (est.)

January 31, 1906Ecuador

Colombia

1906 Ecuador-

Colombia

earthquake

8.8

Large earthquakes of the World
http://en.wikipedia.org/wiki/Valdivia,_Chilehttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/1960_Valdivia_earthquakehttp://en.wikipedia.org/wiki/1960_Valdivia_earthquakehttp://en.wikipedia.org/wiki/Prince_William_Soundhttp://en.wikipedia.org/wiki/Prince_William_Soundhttp://en.wikipedia.org/wiki/Alaskahttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/1964_Alaska_earthquakehttp://en.wikipedia.org/wiki/1964_Alaska_earthquakehttp://en.wikipedia.org/wiki/Indian_Oceanhttp://en.wikipedia.org/wiki/Sumatrahttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunamihttp://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunamihttp://en.wikipedia.org/wiki/Kamchatkahttp://en.wikipedia.org/wiki/Russiahttp://en.wikipedia.org/wiki/Soviet_Unionhttp://en.wikipedia.org/wiki/Kamchatka_earthquakeshttp://en.wikipedia.org/wiki/Kamchatka_earthquakeshttp://en.wikipedia.org/wiki/Pacific_Oceanhttp://en.wikipedia.org/wiki/T%C5%8Dhoku_regionhttp://en.wikipedia.org/wiki/Japanhttp://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquakehttp://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquakehttp://en.wikipedia.org/wiki/Sumatrahttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/1833_Sumatra_earthquakehttp://en.wikipedia.org/wiki/1833_Sumatra_earthquakehttp://en.wikipedia.org/wiki/Ecuadorhttp://en.wikipedia.org/wiki/Colombiahttp://en.wikipedia.org/wiki/1906_Ecuador-Colombia_earthquakehttp://en.wikipedia.org/wiki/1906_Ecuador-Colombia_earthquakehttp://en.wikipedia.org/wiki/1906_Ecuador-Colombia_earthquakehttp://en.wikipedia.org/wiki/1906_Ecuador-Colombia_earthquakehttp://en.wikipedia.org/wiki/1906_Ecuador-Colombia_earthquakehttp://en.wikipedia.org/wiki/1906_Ecuador-Colombia_earthquakehttp://en.wikipedia.org/wiki/1906_Ecuador-Colombia_earthquakehttp://en.wikipedia.org/wiki/Colombiahttp://en.wikipedia.org/wiki/Ecuadorhttp://en.wikipedia.org/wiki/1833_Sumatra_earthquakehttp://en.wikipedia.org/wiki/1833_Sumatra_earthquakehttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/Sumatrahttp://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquakehttp://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquakehttp://en.wikipedia.org/wiki/Japanhttp://en.wikipedia.org/wiki/T%C5%8Dhoku_regionhttp://en.wikipedia.org/wiki/Pacific_Oceanhttp://en.wikipedia.org/wiki/Kamchatka_earthquakeshttp://en.wikipedia.org/wiki/Kamchatka_earthquakeshttp://en.wikipedia.org/wiki/Soviet_Unionhttp://en.wikipedia.org/wiki/Russiahttp://en.wikipedia.org/wiki/Kamchatkahttp://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunamihttp://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunamihttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/Sumatrahttp://en.wikipedia.org/wiki/Indian_Oceanhttp://en.wikipedia.org/wiki/1964_Alaska_earthquakehttp://en.wikipedia.org/wiki/1964_Alaska_earthquakehttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/Alaskahttp://en.wikipedia.org/wiki/Prince_William_Soundhttp://en.wikipedia.org/wiki/Prince_William_Soundhttp://en.wikipedia.org/wiki/1960_Valdivia_earthquakehttp://en.wikipedia.org/wiki/1960_Valdivia_earthquakehttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/Valdivia,_Chile

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February 27,

2010Maule, Chile

2010 Chile

earthquake8.8

January 26, 1700 Pacific Ocean,USA and Canada

1700 Cascadiaearthquake

8.79.2 (est.)

July 8, 1730 Valparaiso, Chile1730 Valparaiso


November 1,

1755

Atlantic Ocean,

Lisbon, Portugal

1755 Lisbon

earthquake

8.7 (est.)

February 4, 1965Rat Islands,

Alaska, USA

1965 Rat Islands

earthquake8.7

July 9, 869

Pacific Ocean,

Thoku region,

Japan

869 Sanriku

earthquake8.6 (est.)

October 28,

1707

Pacific Ocean,

Shikoku region,

Japan

1707 Hei

http://en.wikipedia.org/wiki/Maule_Regionhttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/2010_Chile_earthquakehttp://en.wikipedia.org/wiki/2010_Chile_earthquakehttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/Canadahttp://en.wikipedia.org/wiki/1700_Cascadia_earthquakehttp://en.wikipedia.org/wiki/1700_Cascadia_earthquakehttp://en.wikipedia.org/wiki/Valparaisohttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/1730_Valparaiso_earthquakehttp://en.wikipedia.org/wiki/1730_Valparaiso_earthquakehttp://en.wikipedia.org/wiki/Atlantic_Oceanhttp://en.wikipedia.org/wiki/Lisbonhttp://en.wikipedia.org/wiki/Portugalhttp://en.wikipedia.org/wiki/1755_Lisbon_earthquakehttp://en.wikipedia.org/wiki/1755_Lisbon_earthquakehttp://en.wikipedia.org/wiki/Rat_Islandshttp://en.wikipedia.org/wiki/Alaskahttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/1965_Rat_Islands_earthquakehttp://en.wikipedia.org/wiki/1965_Rat_Islands_earthquakehttp://en.wikipedia.org/wiki/T%C5%8Dhoku_regionhttp://en.wikipedia.org/wiki/Japanhttp://en.wikipedia.org/wiki/869_Sanriku_earthquake_and_tsunamihttp://en.wikipedia.org/wiki/869_Sanriku_earthquake_and_tsunamihttp://en.wikipedia.org/wiki/Shikoku_regionhttp://en.wikipedia.org/wiki/Japanhttp://en.wikipedia.org/wiki/1707_H%C5%8Dei_earthquakehttp://en.wikipedia.org/wiki/1707_H%C5%8Dei_earthquakehttp://en.wikipedia.org/wiki/1707_H%C5%8Dei_earthquakehttp://en.wikipedia.org/wiki/1707_H%C5%8Dei_earthquakehttp://en.wikipedia.org/wiki/Japanhttp://en.wikipedia.org/wiki/Shikoku_regionhttp://en.wikipedia.org/wiki/869_Sanriku_earthquake_and_tsunamihttp://en.wikipedia.org/wiki/869_Sanriku_earthquake_and_tsunamihttp://en.wikipedia.org/wiki/Japanhttp://en.wikipedia.org/wiki/T%C5%8Dhoku_regionhttp://en.wikipedia.org/wiki/1965_Rat_Islands_earthquakehttp://en.wikipedia.org/wiki/1965_Rat_Islands_earthquakehttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/Alaskahttp://en.wikipedia.org/wiki/Rat_Islandshttp://en.wikipedia.org/wiki/1755_Lisbon_earthquakehttp://en.wikipedia.org/wiki/1755_Lisbon_earthquakehttp://en.wikipedia.org/wiki/Portugalhttp://en.wikipedia.org/wiki/Lisbonhttp://en.wikipedia.org/wiki/Atlantic_Oceanhttp://en.wikipedia.org/wiki/1730_Valparaiso_earthquakehttp://en.wikipedia.org/wiki/1730_Valparaiso_earthquakehttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/Valparaisohttp://en.wikipedia.org/wiki/1700_Cascadia_earthquakehttp://en.wikipedia.org/wiki/1700_Cascadia_earthquakehttp://en.wikipedia.org/wiki/Canadahttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/2010_Chile_earthquakehttp://en.wikipedia.org/wiki/2010_Chile_earthquakehttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/Maule_Region

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August 15, 1950

Assam, India

Tibet, China

1950 Medog

earthquake 8.6

March 9, 1957

Andreanof

Islands, Alaska,

USA

1957 Andreanof

Islands

earthquake

8.6

March 28, 2005Sumatra,

Indonesia

2005 Sumatra

earthquake8.6

August 13, 1868Arica, Chile

(then Peru)

1868 Arica


December 16,

1575

Valdivia, Chile

(Kingdom of

Chile)

1575 Valdivia


October 20,

1687

Lima, Peru

(Viceroyalty of

Peru)

1687 Peru

http://en.wikipedia.org/wiki/Assamhttp://en.wikipedia.org/wiki/Indiahttp://en.wikipedia.org/wiki/Tibethttp://en.wikipedia.org/wiki/Chinahttp://en.wikipedia.org/wiki/1950_Medog_earthquakehttp://en.wikipedia.org/wiki/1950_Medog_earthquakehttp://en.wikipedia.org/wiki/Andreanof_Islandshttp://en.wikipedia.org/wiki/Andreanof_Islandshttp://en.wikipedia.org/wiki/Alaskahttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/1957_Andreanof_Islands_earthquakehttp://en.wikipedia.org/wiki/1957_Andreanof_Islands_earthquakehttp://en.wikipedia.org/wiki/1957_Andreanof_Islands_earthquakehttp://en.wikipedia.org/wiki/Sumatrahttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/2005_Sumatra_earthquakehttp://en.wikipedia.org/wiki/2005_Sumatra_earthquakehttp://en.wikipedia.org/wiki/Aricahttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/Peruhttp://en.wikipedia.org/wiki/1868_Arica_earthquakehttp://en.wikipedia.org/wiki/1868_Arica_earthquakehttp://en.wikipedia.org/wiki/Valdivia,_Chilehttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/Captaincy_General_of_Chilehttp://en.wikipedia.org/wiki/Captaincy_General_of_Chilehttp://en.wikipedia.org/wiki/1575_Valdivia_earthquakehttp://en.wikipedia.org/wiki/1575_Valdivia_earthquakehttp://en.wikipedia.org/wiki/Limahttp://en.wikipedia.org/wiki/Peruhttp://en.wikipedia.org/wiki/Viceroyalty_of_Peruhttp://en.wikipedia.org/wiki/Viceroyalty_of_Peruhttp://en.wikipedia.org/wiki/1687_Peru_earthquakehttp://en.wikipedia.org/wiki/1687_Peru_earthquakehttp://en.wikipedia.org/wiki/1687_Peru_earthquakehttp://en.wikipedia.org/wiki/1687_Peru_earthquakehttp://en.wikipedia.org/wiki/Viceroyalty_of_Peruhttp://en.wikipedia.org/wiki/Viceroyalty_of_Peruhttp://en.wikipedia.org/wiki/Peruhttp://en.wikipedia.org/wiki/Limahttp://en.wikipedia.org/wiki/1575_Valdivia_earthquakehttp://en.wikipedia.org/wiki/1575_Valdivia_earthquakehttp://en.wikipedia.org/wiki/Captaincy_General_of_Chilehttp://en.wikipedia.org/wiki/Captaincy_General_of_Chilehttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/Valdivia,_Chilehttp://en.wikipedia.org/wiki/1868_Arica_earthquakehttp://en.wikipedia.org/wiki/1868_Arica_earthquakehttp://en.wikipedia.org/wiki/Peruhttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/Aricahttp://en.wikipedia.org/wiki/2005_Sumatra_earthquakehttp://en.wikipedia.org/wiki/2005_Sumatra_earthquakehttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/Sumatrahttp://en.wikipedia.org/wiki/1957_Andreanof_Islands_earthquakehttp://en.wikipedia.org/wiki/1957_Andreanof_Islands_earthquakehttp://en.wikipedia.org/wiki/1957_Andreanof_Islands_earthquakehttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/Alaskahttp://en.wikipedia.org/wiki/Andreanof_Islandshttp://en.wikipedia.org/wiki/Andreanof_Islandshttp://en.wikipedia.org/wiki/1950_Medog_earthquakehttp://en.wikipedia.org/wiki/1950_Medog_earthquakehttp://en.wikipedia.org/wiki/Chinahttp://en.wikipedia.org/wiki/Tibethttp://en.wikipedia.org/wiki/Indiahttp://en.wikipedia.org/wiki/Assam

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May 24, 1751

Concepcin,

Chile (Kingdom

of Chile)

1751

Concepcin

earthquake

8.5 (est.)

November 11,

1922

Atacama

Region, Chile

1922 Vallenar

earthquake8.5

February 3,

1923

Kamchatka,

Russia (USSR)

1923 Kamchatka

earthquakes8.5

February 1,

1938

Banda Sea,Indonesia

(Dutch East

Indies)

1938 Banda Sea

earthquake8.5

October 13,

1963

Kuril Islands,

Russia (USSR)

1963 Kuril

Islandsearthquake

8.5

September 12,

2007

Sumatra,

Indonesia

2007 Sumatra

earthquakes8.5
http://en.wikipedia.org/wiki/Concepci%C3%B3n,_Chilehttp://en.wikipedia.org/wiki/Captaincy_General_of_Chilehttp://en.wikipedia.org/wiki/Captaincy_General_of_Chilehttp://en.wikipedia.org/wiki/1751_Concepci%C3%B3n_earthquakehttp://en.wikipedia.org/wiki/1751_Concepci%C3%B3n_earthquakehttp://en.wikipedia.org/wiki/1751_Concepci%C3%B3n_earthquakehttp://en.wikipedia.org/wiki/Atacama_Regionhttp://en.wikipedia.org/wiki/Atacama_Regionhttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/1922_Vallenar_earthquakehttp://en.wikipedia.org/wiki/1922_Vallenar_earthquakehttp://en.wikipedia.org/wiki/Kamchatka_Peninsulahttp://en.wikipedia.org/wiki/Russiahttp://en.wikipedia.org/wiki/Soviet_Unionhttp://en.wikipedia.org/wiki/Kamchatka_earthquakeshttp://en.wikipedia.org/wiki/Kamchatka_earthquakeshttp://en.wikipedia.org/wiki/Banda_Seahttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/Dutch_East_Indieshttp://en.wikipedia.org/wiki/Dutch_East_Indieshttp://en.wikipedia.org/wiki/1938_Banda_Sea_earthquakehttp://en.wikipedia.org/wiki/1938_Banda_Sea_earthquakehttp://en.wikipedia.org/wiki/Kuril_Islandshttp://en.wikipedia.org/wiki/Russiahttp://en.wikipedia.org/wiki/Soviet_Unionhttp://en.wikipedia.org/wiki/1963_Kuril_Islands_earthquakehttp://en.wikipedia.org/wiki/1963_Kuril_Islands_earthquakehttp://en.wikipedia.org/wiki/1963_Kuril_Islands_earthquakehttp://en.wikipedia.org/wiki/Sumatrahttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/September_2007_Sumatra_earthquakeshttp://en.wikipedia.org/wiki/September_2007_Sumatra_earthquakeshttp://en.wikipedia.org/wiki/September_2007_Sumatra_earthquakeshttp://en.wikipedia.org/wiki/September_2007_Sumatra_earthquakeshttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/Sumatrahttp://en.wikipedia.org/wiki/1963_Kuril_Islands_earthquakehttp://en.wikipedia.org/wiki/1963_Kuril_Islands_earthquakehttp://en.wikipedia.org/wiki/1963_Kuril_Islands_earthquakehttp://en.wikipedia.org/wiki/Soviet_Unionhttp://en.wikipedia.org/wiki/Russiahttp://en.wikipedia.org/wiki/Kuril_Islandshttp://en.wikipedia.org/wiki/1938_Banda_Sea_earthquakehttp://en.wikipedia.org/wiki/1938_Banda_Sea_earthquakehttp://en.wikipedia.org/wiki/Dutch_East_Indieshttp://en.wikipedia.org/wiki/Dutch_East_Indieshttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/Banda_Seahttp://en.wikipedia.org/wiki/Kamchatka_earthquakeshttp://en.wikipedia.org/wiki/Kamchatka_earthquakeshttp://en.wikipedia.org/wiki/Soviet_Unionhttp://en.wikipedia.org/wiki/Russiahttp://en.wikipedia.org/wiki/Kamchatka_Peninsulahttp://en.wikipedia.org/wiki/1922_Vallenar_earthquakehttp://en.wikipedia.org/wiki/1922_Vallenar_earthquakehttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/Atacama_Regionhttp://en.wikipedia.org/wiki/Atacama_Regionhttp://en.wikipedia.org/wiki/1751_Concepci%C3%B3n_earthquakehttp://en.wikipedia.org/wiki/1751_Concepci%C3%B3n_earthquakehttp://en.wikipedia.org/wiki/1751_Concepci%C3%B3n_earthquakehttp://en.wikipedia.org/wiki/Captaincy_General_of_Chilehttp://en.wikipedia.org/wiki/Captaincy_General_of_Chilehttp://en.wikipedia.org/wiki/Concepci%C3%B3n,_Chile

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Figure 1. Schematic views of Indian tectonics. Plate boundary velocities are indicated in mm/year. Shading indicates flexure of India: a 4 km deep trough near the Himalaya an

Isoseismal of the 2001 Bhuj

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Isoseismal of the 2001 Bhuj

Earthquake, Mw 7.7

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Isoseismals of large earthquakes in India

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The earthquake zoning map of India divides India into 4

seismic zones (Zone 2, 3, 4 and 5) unlike its previous

version which consisted of five or six zones for thecountry. According to the present zoning map, Zone 5

expects the highest level of seismicity whereas Zone 2 is

associated with the lowest level of seismicity.

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Zone 5

Zone 5 covers the areas with the highest risks zone that

suffers earthquakes of intensity MSK IX or greater. The

IS code assigns zone factor of 0.36 for Zone 5. Structural

designers use this factor for earthquake resistant design

of structures in Zone 5. The zone factor of 0.36 is

indicative of effective (zero period) peak horizontal

ground accelerations of 0.36 g (36 % of gravity) that maybe generated by an earthquake in this zone. It is referred

to as the Very High Damage Risk Zone. The state of

Kashmir, Punjab, the western and central Himalayas, the

North-East Indian region and the Rann of Kutch fall in

this zone.Generally, the areas having trap or basaltic rock are

prone to earthquakes.

Zone 4
http://en.wikipedia.org/wiki/MSK-IXhttp://en.wikipedia.org/wiki/Peak_ground_accelerationhttp://en.wikipedia.org/wiki/Peak_ground_accelerationhttp://en.wikipedia.org/wiki/Kashmirhttp://en.wikipedia.org/wiki/Punjab_(India)http://en.wikipedia.org/wiki/Himalayashttp://en.wikipedia.org/wiki/Rann_of_Kutchhttp://en.wikipedia.org/wiki/Rann_of_Kutchhttp://en.wikipedia.org/wiki/Himalayashttp://en.wikipedia.org/wiki/Punjab_(India)http://en.wikipedia.org/wiki/Kashmirhttp://en.wikipedia.org/wiki/Peak_ground_accelerationhttp://en.wikipedia.org/wiki/Peak_ground_accelerationhttp://en.wikipedia.org/wiki/MSK-IX

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Zone 4

This zone is called the High Damage Risk Zone and

covers areas liable to MSK VIII. The IS code assignszone factor of 0.24 for Zone 4. The Indo-Gangetic basin

and the capital of the country (Delhi), Jammu and Bihar

fall in Zone 4. In Maharashtra Patan area(Koyananager)

also in zone 4.

Zone 3

TheAndaman and Nicobar Islands, parts ofKashmir,

Western Himalayas fall under this zone. This zone isclassified as Moderate Damage Risk Zone which is

liable to MSK VII. and also 7.8 The IS code assigns

zone factor of 0.18 for Zone 3.
http://en.wikipedia.org/wiki/Andaman_and_Nicobar_Islandshttp://en.wikipedia.org/wiki/Kashmirhttp://en.wikipedia.org/wiki/Kashmirhttp://en.wikipedia.org/wiki/Andaman_and_Nicobar_Islands

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Zone 2

This region is liable to MSK VI or less and is classified asthe Low Damage Risk Zone. The IS code assigns zone

factor of 0.10 (maximum horizontal acceleration that can

be experienced by a structure in this zone is 10 % of

gravitational acceleration) for Zone 2.

H ds ss i t d ith Q k s

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Hazards associated with Quakes Shaking:

Frequency of shaking differs for different seismic waves.High frequency body waves shake low buildings more.

Low frequency surface waves shake high buildings more.Intensity of shaking also depends on type of subsurface material.Unconsolidated materials amplify shaking more than rocks do.Fine-grained, sensitive materials can lose strength when shaken. They losestrength by liquefaction.Buildings respond differently to shaking depending on construction styles,materials

Wood -- more flexible, holds up wellEarthen materials -- very vulnerable to shaking.

Ground displacement:Ground surface may shift during an earthquake (esp. if focus is shallow).Vertical displacements of surface produce fault scarps.

Tsunamis (NOT tidal waves)

Tsunamis are huge waves generated by earthquakes undersea or belowcoastal areas.If earthquake displaces sea surface, wave is generated that can grow as itmoves over sea surface.

FiresUsually occurs from shifting of subsurface utilities (gas lines)

More reasonable assessment, based upon actual seismicity

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The Global Seismic Hazard Assessment Program (GSHAP), with the support

of the International Council of Scientific Unions (ICSU), and endorsed as a

demonstration program in the framework of the United Nations International

Decade for Natural Disaster Reduction (UN/IDNDR).

Earthquake Hazard Potential Map

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Parkfield, CA

Earthquake Capital of the World

q p

Ground Acceleration

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Seismologists usually define strong ground motion as the

strong earthquake shaking that occurs close to(less than about 50 km from) a causative fault.

The strength of the shaking involved in strong ground

motion usually overwhelms a seismometer, forcing the use of

accelerographs (or strong ground motion accelerometers)for recording.

Ground Acceleration
http://en.wikipedia.org/wiki/Seismologyhttp://en.wikipedia.org/wiki/Earthquakehttp://en.wikipedia.org/wiki/Geologic_faulthttp://en.wikipedia.org/wiki/Seismometerhttp://en.wikipedia.org/wiki/Accelerographhttp://en.wikipedia.org/wiki/Accelerometerhttp://en.wikipedia.org/wiki/Accelerometerhttp://en.wikipedia.org/wiki/Accelerographhttp://en.wikipedia.org/wiki/Seismometerhttp://en.wikipedia.org/wiki/Geologic_faulthttp://en.wikipedia.org/wiki/Earthquakehttp://en.wikipedia.org/wiki/Seismology

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What Controls the Level of Shaking?

Magnitude

More energy released

Distance Shaking decays with distance

Local soils

amplify the shaking

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Intense ground shaking during large

earthquakes can damage or even cause failureof engineered structures such as buildings,

bridges, highways, and dams. Sustained strong

shaking can also trigger ground failures, such

as rock falls, landslides, earth flows andliquefaction. Strong motion seismology uses

special sensors, called accelerometers, to

record these large-amplitude ground motions

and the response of engineered structures tothese motions.

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Comparison of peak ground acceleration with the damage intensities and zone factors as

defined by IS 1893 : 2002

IS code seismic zone II III IV V

Perceived shaking Moderate Strong Very strong Severe

Potential damage Very light Light Moderate Moderate

heavy

Peak acceleration (%g) 3.99.2 9.218 1834 3465

Ground Acceleration of India

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Ground Acceleration of India

DAMAGE DEPENDS ON BUILDING TYPE

RESISTANT CONSTRUCTION REDUCES EARTHQUAKE RISKS

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0.2 gDamage

onset for

modern

buildings

RESISTANT CONSTRUCTION REDUCES EARTHQUAKE RISKS

Earthquakes don't kill people; buildings kill people." Coburn &Spence 1992

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Social Impacts

(impact on people)

Economic Impacts

(impact on

business in the

area)

Environmental

Impacts (impact

on the landscape)

Primary effects Death,

Homes destroyed,Services e.g. water

disrupted,

Transport systems

damaged

Businesses &

property destroyed,

Landscape

destroyed,

Secondary effects Diseases Looting,

Economic effect ofrestoring

businesses

Fires,

Tidal Waves,Landslides

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COMPLEX PLATE

BOUNDARY ZONE IN

SOUTHEAST ASIA

Northward motion of

India deforms all of

the region

Many small plates

(microplates) andblocks

Molnar & Tapponier, 1977

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Tsunami Movement: ~600 mph in deep water

~250 mph in medium depth water

~35 mph in shallow water

TSUNAMI - water wave generated by earthquake

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NY Times

Worlds Largest Earthquake: 1964 Anchorage, Alaska

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Registered 8.6 on Richter Scale

Tsunami Movement

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NOAA

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IN DEEP OCEAN tsunami has long wavelength, travels fast,

small amplitude - doesnt affect ships

AS IT APPROACHES SHORE, it slows. Since energy is

conserved, amplitude builds up - very damaging

TSUNAMI WARNING

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Because seismic waves travel much

faster (km/s) than tsunamis, rapid

analysis of seismograms can identify

earthquakes likely to cause major

tsunamis and predict when waves will

arrive

Deep ocean buoys can measure

wave heights, verify tsunami and

reduce false alarms

Earthquake Prediction

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Earthquake Prediction:

Precursory Events

Ex/ 1989 Loma Prieta

Earthquake

Soil Helium Variation

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Also: Resistivity, water pressure and well levels, geyser

activity, changes in seismicity

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Earthquake Prediction: Animal Behavior??

Another Approach: Forecasting

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Seismic Gap Hypothesis

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Short-Term Crustal Deformation Precursor

Mogi, 1984

Short-Term Electromagnetic Precursor

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Short Term Electromagnetic Precursor

Fraser-Smith, et al., 1990

Paleoseismology

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M >7 mean = 132 yr s = 105 yr

Estimated probability in 30 yrs 7-51%

Sieh et al., 1989Extend earthquake

history with geologic

record

FREQUENCY-MAGNITUDE RELATIONSHIP

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For New Madrid,combine instrumental

seismology with earlierdata to explore largeearthquake recurrence

Largepaleoearthquakes

occurred at~ 1450 and 900 AD(Magnitudes unknown)

Gives a M7 every

few thousand years.

Might NEVER get aM8 earthquake

Stein & Newman, 2004

?

Earthquake Cycle

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Periodic Time-predicatable Slip-predicatable

Shimazaki and Nakata, 1980

Earthquake Cycle

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Parkfield, California,

showed evidence of the

recurrence of similar-sized

(M 6.0) earthquakes

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In 1985 a 6.0 Parkfield earthquake was predicted with 95% confidence to

occur by 1993.

Mean = (1966-1857)/5 = 22 years

Expected date = 1988

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Didnt occur until 2004

(16 years late!)

Was it a success?

Right size, right location,wrong date.

Prediction of the 1975 Haicheng, China

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g

Earthquake (M7.3)

Prediction based on foreshocks

and animal behavior saved many

lives

Documents

Lecture 22 23