u.s. geological survey m7.5 northern peru earthquake of 26 … · 2005-10-17 · map prepared by...

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Geophysical Data Center IASPEI, Centennial Catalog (1900 - 1999) and extensions (Engdahl and Villaseñor, 2002) HDF (unpublished earthquake catalog) (Engdahl, 2003) USGS (2003), National Seismic Hazard Maps Global Seismic Hazard Assessment Program (GSHAP, 1999)FAULTS AND FOLDS USGS,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.

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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

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A m a z o n a s

N a p o

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Ucayal i

Golfo deGuayaquil

P u t u m a y o

I c á

73 mm/yr

Seismotectonic Setting

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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°

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N O R T HA N D E SP L AT E

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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


0 100 200 300 40050Kilometers


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.


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


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


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

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26 September 2005

Earthquakes 1900 - 20050 - 69 km70 - 299300 - 700


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.



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2005

EPICENTRAL AREAEPICENTRAL AREA

u.s. geological survey m7.5 northern peru earthquake of 26 … · 2005-10-17 · map prepared by...

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