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Map prepared by U.S. Geological SurveyNational Earthquake Information Center17 October 2005Map not approved for release by Director USGS
DATA SOURCESEARTHQUAKES AND SEISMIC HAZARD USGS, National Earthquake Information Center NOAA, National Geophysical Data Center IASPEI, Centennial Catalog (1900 - 1999) and extensions (Engdahl and Villaseñor, 2002) HDF (unpublished earthquake catalog) (Engdahl, 2003) USGS (2003), National Seismic Hazard Maps Global Seismic Hazard Assessment Program (GSHAP, 1999)FAULTS AND FOLDS USGS, Quaternary Faults and Folds DatabasePLATE TECTONICS PB2002 (Bird, 2003)VOLCANOES Smithsonian Institution, Global Volcano ProgramBASE MAP ESRI (1992), Digital Chart of the World GLOBE (1999) IOC, IHO, and BODC (2003)
EARTHQUAKE SUMMARY MAP XXXU.S. DEPARTMENT OF THE INTERIORU.S. GEOLOGICAL SURVEY
DISCLAIMERBase map data, such as place names and politicalboundaries, are the best available but may not be current or may contain inaccuracies and thereforeshould not be regarded as having official significance.
M7.5 Northern Peru Earthquake of 26 September 2005
REFERENCESBird, P., 2003, An updated digital model of plate boundaries: Geochem. Geophys. Geosyst., v. 4, no. 3, pp. 1027- 80.Engdahl, E.R. and Villaseñor, A., 2002, Global Seismicity: 1900 - 1999, chap. 41 of Lee, W.H.K., and others,eds., International Earthquake and Engineering Seismology, Part A: New York, N.Y., Elsevier Academic Press, 932 p.Engdahl, E.R., Van der Hilst, R.D., and Buland, R.P., 1998, Global teleseismic earthquake relocation with improved trav- el times and procedures for depth determination: Bull. Seism. Soc. Amer., v. 88, p. 722-743.Environmental Systems Research Institute, Inc., 1992, 1993, Digital Chart of the World: ESRI, Data Dictionary and CD- ROM(4), Redlands, Calif., USA.GLOBE Task Team and others, 1999, The Global Land One- Kilometer Base Elevation (GLOBE) Digital Elevation Model, Version 1.0: National Oceanic and Atmospheric Administra- tion, Boulder, Colo., USA.IOC, IHO, and BODC, 2003, Centenary Edition of the GEBCO Digital Atlas: CD-ROM(2), British Oceanographic Data Centre, Liverpool, UK.
P E R U
E C U A D O R
B R A Z I L
M a r a ñ ó n
Uc a
y a l i
L o r e t o
S a n M a r t i n
A m a z o n a s
C a j a m a r c a
A c r eU c a y a l i
L a L i b e r t a d
L o j a
A z u a y
A n c a s h
P i u r a
A m a z o n a s
Z a m o r a - C h i n c h i p e
M o r o n a - S a n t i a g oE l O r o
G u a y a s
H u a n u c oViru
Sion
SANA
Jaen
LOJA
Lucma
Sucre
Maria
LamasRoqueSalas
RiojaOLMOS
Bagua
Nauta
Nanay
TamboYaupi
Shilco
Simbal Parcoy
CharatPaijan
Cospan ShepteOsilin
NieposOyotun
ChalanChugur
PelejoOcalliMOTUPE
Toledo
Serran
Ugarte
Zamora
SoplinPasaje
CUENCA
RemansoTaurijaCalipuy Pellejo
Chillia
ChocopeAchiras
BolivarChilete Juanjui
Huasmin
ChasutaMendoza Navarro
Cutervo
AlianzaCujillo
Churuja
Jamalca
Requena
Bolivar
IQUITOS
PUCALLPA Deposito
BotafagoTRUJILLO
Naranjal
Libertad
OrellanaPucacaca
Tarapoto
Tocmoche Convento
YanayacuJumbilla
OrellanaParinari
Catamayo
Libertad
AmazonasBermejos
Boca Apua
TayabambaConchucosSalaverryBoa VistaBuldibuyoCarabamba
Huanchaco
HuacamayoCashiboyaCAJABAMBA
SitacochaRepublicaPACASMAYO Contumaza Contamana
LlacanoraCAJAMARCASan Pablo Uchumarca
Piscoyacu Sao Paulo
Rodriquez
MAYOBAMBAYuracyacu
Capanahua
ArahuanteTabaconas
EsperanzaSan Roque
Huamanzana
Uningambal Tre UnidosMollebamba
HuamachucoAricapampa
Condomarca
San Marcos
Chongoyape
Yurimaguas
Bellavista
Cariamanga
BellavistaChinganaza
Santa Rosa
Gualaquiza
Oro BlancoGuagramonoSanta Rosa
Negro UrcoBellavista
Nuevo Paris
Dos de Mayo
CHACHAPOYAS
Santa Clara
Chingozales
Platanoyacu
Puerto Morin
Mollebambita
Pueblo Nuevo
San Jeronimo
Puerto Pardo
Puerto Copal
Tacache Nuevo
Puerto PizanaSan Francisco
Pampa Fermosa
Tierra Blanca
Puerto FrancoSoldado Silva
Puerto Olivia
Puerto Morona
Puerto Chicama
Puesto Bagazan
Santiago de Cao
Teniente Pinglo
Puerto Guacamayo
San Pedro de Lloc
Veintiocho de Mayo
Subteniente Castro
Santo Tomas de AndoasGeneral Plaza Gutierrez
79°0'W
79°0'W
78°0'W
78°0'W
77°0'W
77°0'W
76°0'W
76°0'W
75°0'W
75°0'W
74°0'W
74°0'W
73°0'W
73°0'W
8°0'S 8°0'S
7°0'S 7°0'S
6°0'S 6°0'S
5°0'S 5°0'S
4°0'S 4°0'S
3°0'S 3°0'S
82° 81° 80° 79° 78° 77° 76° 75° 74° 73° 72° 71° 70° 69° 68°
82° 81° 80° 79° 78° 77° 76° 75° 74° 73° 72° 71° 70° 69° 68°
12°
11°
10°
9°
8°
7°
6°
5°
4°
3°
2°
1°
0°
12°
11°
10°
9°
8°
7°
6°
5°
4°
3°
2°
1°
0°Quito
Guayaquil
P E R U
E C U A D O R
B R A Z I L
B O L I V I A
C O L O M B I A
P A C I F I CO C E A N
P E RU - C
H I L E T R E N C H
AN
DE
S
Co
r di l l e r a O
c c i d e n t a l
La M
o n t a ñ a
Co r d
i l l e r a Ce n t r a l
Co r d i l l e r a O
r i e n t a l
A M A Z O N B A S I N
S O U T H A M E R I C A P L AT E
N O R T HA N D E SP L AT E
N A Z C AP L AT E
A m a z o n a s
N a p o
M a r a ñ ó n
Ucayal i
Golfo deGuayaquil
P u t u m a y o
I c á
73 mm/yr
Seismotectonic Setting
A
A'
B
B'
NORTHERN PERU26 September 2005 01:55:37.64 UTC5.674° S., 76.409° W.Depth 127 kmMw = 7.5 (USGS)Five people killed, at least 60 injured, about 70 percent of the houses destroyed and at least 200 buildings dam-aged at Lamas. Damage to buildings at Chachapoyas, Moyobamba and Tarapota. Felt (IV) at Cajamarca, Lima and Trujillo; (III) at Manta. Felt (VI) at Cuenca and Loja, (III) at Quito, Ecuador and (II) at Bogota, Colombia. Felt throughout Peru and Ecuador. Also felt in the Amazonas and Rondonia states, Brazil.
82° 81° 80° 79° 78° 77° 76° 75° 74° 73° 72° 71° 70° 69° 68°
82° 81° 80° 79° 78° 77° 76° 75° 74° 73° 72° 71° 70° 69° 68°
12°
11°
10°
9°
8°
7°
6°
5°
4°
3°
2°
1°
0°
12°
11°
10°
9°
8°
7°
6°
5°
4°
3°
2°
1°
0°Quito
Guayaquil
P E R U
E C U A D O R
B R A Z I L
B O L I V I A
C O L O M B I A
P A C I F I CO C E A N
P E RU - C
H I L E T R E N C H
AN
DE
S
Co
r di l l e r a O
c c i d e n t a l
La M
o n t a ñ a
Co r d
i l l e r a Ce n t r a l
Co r d i l l e r a O
r i e n t a l
A M A Z O N B A S I N
S O U T H A M E R I C A P L AT E
N O R T HA N D E SP L AT E
N A Z C AP L AT E
A m a z o n a s
N a p o
M a r a ñ ó n
Ucayal i
Golfo deGuayaquil
P u t u m a y o
I c á
73 mm/yr
Generalized Seismic Hazard
DISCUSSIONThis major earthquake occurred within the lithosphere of the oceanic Nazca plate. The earthquakes of northern Peru and most of western South America are due to strains generated by ongoing subduction of the Nazca plate beneath the South America plate. The Nazca platemoves east relative to the South America plate at a rate of about 7 cm per year. It is overridden by the South America plate at the Peru-Chile trench, west of the Peruvian coast, and sinks into the Earth's mantle beneath the South America plate. The subducted Nazca plate is seis-mically active to depths of about 650 km. This earthquake occurred in a segment of the subducted plate that has produced frequent earth-quakes with focal depths of 100 km to 150 km beneath the Earth's surface. A magnitude 7.2 earthquake in 1997 was situated 150 km to the north of the 26 September 2005 earthquake, at a similar depth. Earthquakes that have focal-depths between 70 and 300 km are commonly termed 'intermediate-depth' earthquakes, as distinguished from 'shallow-focus' earthquakes, having depths less than 70 km, and 'deep-focus' earthquakes, having depths greater than 300 km. Intermediate-depth and deep-focus earthquakes represent deform-ation within subducted plates, rather than deformation at plate boundaries. Intermediate-depth and deep-focus earthquakes typically cause less damage on the ground surface above their foci than is the case with similar magnitude shallow-focus earthquakes, but large intermediate-depth and deep-focus earthquakes may be felt at great distances from their epicenters.
0 50 100 150 20025Kilometers
SCALE 1:2,500,000 at the EquatorMercator Projection
0 100 200 300 40050Kilometers
SCALE 1:7,500,000 at the EquatorMercator Projection
0 100 200 300 40050Kilometers
SCALE 1:7,500,000 at the EquatorMercator Projection
EXPLANATIONMain Shock
26 September 2005
Earthquakes 1900 - 20050 - 69 km70 - 299
Magnitude Classes3.0 - 3.94.0 - 4.95.0 - 5.96.0 - 6.97.0 - 7.9
8.0 - 8.9
RELATIVE PLATE MOTIONSThe relative motion of adjacent tectonicplates is depicted on the map by short vectors located at selected points on the plate boundary. In this presentation, the vector therefore represents the direction of the moving plate relative to the adjac-ent reference plate. The rate of relative motion is labelled next to the vector.The components of the vector perpen-dicular and parallel to the plate margin approximate convergent/divergent and transverse direction of motion between the plates, respectively. As viewed from the reference plate, an inward directed component suggests convergence at and near the plate boundary that may be expressed as crustal folding, uplift, thrustfaulting, or plate subduction. Similarly, an outward directed component sug-gests plate divergence such as would be expected at a zone of crustal spread-ing. Transcurrent or transform faultingwould be expected when the predom-inant vector component is parallel to theplate margin.
EXPLANATIONMain Shock
26 September 2005
Earthquakes 1900 - 20050 - 69 km70 - 299300 - 699
Magnitude Classes3.0 - 3.94.0 - 4.95.0 - 5.96.0 - 6.97.0 - 7.98.0 - 8.9
Plate Boundary TypeContinental CompressiveContinental RL TransformSubduction
Volcano
EXPLANATIONMain Shock
26 September 2005
Seismic Hazard0.2 - 0.4 m/sec²0.4 - 0.80.8 - 1.61.6 - 3.23.2 - 6.46.4 - 9.0
Earthquakes 1900 - 20050 - 69 km70 - 299300 - 699
Magnitude Classes3.0 - 3.94.0 - 4.95.0 - 5.96.0 - 6.97.0 - 7.98.0 - 8.9
Plate Boundary TypeContinental CompressiveContinental RL TransformSubduction
Volcano
Seismic hazard is expressed as peak ground acceleration (PGA) on firm rock,in meters/sec², expected to be exceededin a 50-yr period with a probability of 10 percent.
Epicentral Area
0 km 100 km 200 km 300 km 400 km 500 km 600 km 700 km 800 km 900 km 1000 km 1100 km
0 km 100 km 200 km 300 km 400 km 500 km 600 km 700 km 800 km 900 km 1000 km 1100 km
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B B'
EXPLANATIONMain Shock
26 September 2005
Earthquakes 1900 - 20050 - 69 km70 - 299300 - 700
Magnitude Classes3.0 - 3.94.0 - 4.95.0 - 5.96.0 - 6.97.0 - 7.98.0 - 8.9
COMMUNITY INTERNET INTENSITY MAPThe Community Internet Intensity Map (CIIM) summarizesthe online questionnaire responses provided by Internetusers. An intensity number is assigned to each communityfrom which a filled-out CIIM questionnaire was received;each intensity value reflects the effects of earthquakeshaking on the people and structures in the community.The color of each circular symbol on the map representsthe average of the individual intensity values from thatcommunity; the size of the symbol is related to the popu-lation of the community.
0 km 100 km 200 km 300 km 400 km 500 km 600 km 700 km 800 km 900 km 1000 km 1100 km
0 km 100 km 200 km 300 km 400 km 500 km 600 km 700 km 800 km 900 km 1000 km 1100 km
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0 km
700 km
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500 km
400 km
300 km
200 km
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0 km
A A'Depth Profiles
2005
EPICENTRAL AREAEPICENTRAL AREA