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Titre du document / Document title

The Mw 8.2, 17 February 1996 Biak, Indonesia, earthquake: Rupture history, aftershocks, and fault plane properties

Auteur(s) / Author(s)

HENRY C. (1) ; DAS S. (1) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Department of Earth Sciences, University of Oxford, Oxford, ROYAUME-UNI

Résumé / Abstract

[1] We analyze the rupture history of this earthquake, the largest thrust earthquake since 1977, primarily using broadband SH wave seismograms. We show that the earthquake occurred on a shallow dipping thrust fault (strike 109°, dip 9°, rake 72°) with a seismic moment of 2.7 x 1021 N m. The rupture propagated bilaterally at an average speed of ∼90% of the shear wave speed, on a fault extending 180 km west and 50 km east of the hypocenter, with very variable width ranging from 30 to 100 km at different locations along strike. The mean slip over a 230 km x 100 km fault area was 4 m and the mean stress drop 1.9 MPa. The slip distribution is very nonuniform over the fault, with the largest slip of ∼12 m being near the hypocentral depth (∼10 km). The rupture is very complex, propagating first to the west and then, after a ∼15-s delay, to the east. We interpret this delay as being due to the existence of a inhomogeneous barrier just east of the hypocenter, which initially acted as a barrier to rupture propagation toward the east, but subsequently failed due to stress increase on it generated by the rupture to its west and with the rupture then continuing to propagate eastward. This barrier acted as a stress concentrator before the earthquake, giving rise to foreshocks and was also the initiator of rupture for this earthquake. The aftershock zone closely corresponds to the region in which rupture occurred, the area with greatest aftershock density lying entirely within the area of highest moment release.

Revue / Journal Title

Journal of geophysical research    ISSN  0148-0227 

Source / Source

2002, vol. 107, noB11, pp. ESE11.1-ESE11.16 (32 ref.)

Langue / Language

Anglais

Editeur / Publisher

American Geophysical Union, Washington, DC, ETATS-UNIS  (1949-2012) (Revue)

Mots-clés anglais / English Keywords

Malay Archipelago

;

Asia

;

Far East

;

gravity anomalies

;

seismotectonics

;

foreshocks

;

stress

;

propagation

;

depth

;

stress drops

;

hypocenter

;

shear

;

seismic moment

;

dip

;

strike faults

;

thrust fault

;

seismograms

;

SH-waves

;

fault planes

;

aftershocks

;

rupture

;

earthquakes

;

New Guinea

;

Indonesia

;

Mots-clés français / French Keywords

Archipel Malais

;

Asie

;

Extrême Orient

;

Anomalie gravimétrique

;

Séisme Biak 1996

;

Sismotectonique

;

Onde précurseur

;

Contrainte

;

Propagation

;

Profondeur

;

Relaxation contrainte

;

Hypocentre

;

Cisaillement

;

Moment sismique

;

Pendage

;

Faille longitudinale

;

Faille chevauchement

;

Sismogramme

;

Onde SH

;

Plan faille

;

Réplique sismique

;

Rupture

;

Séisme

;

Nouvelle Guinée

;

Indonésie

;

Mots-clés espagnols / Spanish Keywords

Asia

;

Extremo Oriente

;

Anomalía gravimétrica

;

Sismotectónica

;

Onda precursora

;

Coacción

;

Propagación

;

Profundidad

;

Relajación tensión

;

Hipocentro

;

Cizalladura

;

Momento sísmico

;

Buzamiento

;

Falla longitudinal

;

Cabalgamiento

;

Sismograma

;

Onda SH

;

Plano falla

;

Réplica sísmica

;

Ruptura

;

Sismo

;

Nueva Guinea

;

Indonesia

;

Localisation / Location

INIST-CNRS, Cote INIST : 3144, 35400010951003.0390

Nº notice refdoc (ud4) : 14674271



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