Are rupture zone limits of great subduction earthquakes controlled by upper plate structures? Evidence multichannel seismic reflection data acquired across the norther Ecuador-southwest Colombia margin / Collot, Jaen-Yves

By: Collot, Jean-Yves [autor]
Contributor(s): Marcaillou,, Boris | Sage, Francoise | Michaud, Francois | Agudelo, William | Charves, Philippe
Material type: TextTextLanguage: English Publisher: USA : Journal of Geophysical research, 2004Description: 14 páginas : ilustraciones, mapas papersSubject(s): Morfologóa | Terremotos | Colombia | Ecuador | Reflexión sísmicaOther classification: PUBE-CO-200403-381 Abstract: Subduction of the Nazca plate beneath the Ecuador-Colombia margin has produced four megathrust earthquakes during the last century. The 500-km-long rupture zone of the 1906 (Mw = 8.8) event was partially reactivated by three thrust events, in 1942 (Mw = 7.8), 1958 (Mw = 7.7), and 1979 (Mw = 8.2), whose rupture zones abut one another. Multichannel seismic reflection and bathymetric data acquired during the SISTEUR cruise show evidence that the margin wedge is segmented by transverse crustal faults that potentially correlate with the limits of the earthquake coseismic slip zones. The Paleogene-Neogene Jama Quininde and Esmeraldas crustal faults define a ∼200-km-long margin crustal block that coincides with the 1942 earthquake rupture zone. Subduction of the buoyant Carnegie Ridge is inferred to partially lock the plate interface along central Ecuador. However, coseismic slip during the 1942 and 1906 earthquakes may have terminated against the subducted northern flank of the ridge. We report on a newly identified Manglares crustal fault that cuts transversally through the margin wedge and correlates with the limit between the 1958 and 1979 rupture zones. During the earthquake cycle the fault is associated with high-stress concentration on the plate interface. An outer basement high, which bounds the margin seaward of the 1958 rupture zone, may act as a deformable buttress to seaward propagation of coseismic slip along a megathrust splay fault. Coseismic uplift of the basement high is interpreted as the cause for the 1958 tsunami. We propose a model of weak transverse faults which reduce coupling between adjacent margin segments, together with a splay fault and an asperity along the plate interface as controlling the seismogenic rupture of the 1958 earthquake.
Tags from this library: No tags from this library for this title.
    Average rating: 0.0 (0 votes)
Item type Current location Call number Copy number Status Date due Barcode Item holds
Paper Paper BIBLIOTECA DE ING. DE GEOLOGIA Y PETROLEOS
PUBE-CO-200403- 381 (Browse shelf) Ej. 1 Available 151719
Total holds: 0

Journal of Geophysical Research: Solid Earth Volume 109, Issue B11, November 2004

Incluye : referencias bibliográficas.

Subduction of the Nazca plate beneath the Ecuador-Colombia margin has produced four megathrust earthquakes during the last century. The 500-km-long rupture zone of the 1906 (Mw = 8.8) event was partially reactivated by three thrust events, in 1942 (Mw = 7.8), 1958 (Mw = 7.7), and 1979 (Mw = 8.2), whose rupture zones abut one another. Multichannel seismic reflection and bathymetric data acquired during the SISTEUR cruise show evidence that the margin wedge is segmented by transverse crustal faults that potentially correlate with the limits of the earthquake coseismic slip zones. The Paleogene-Neogene Jama Quininde and Esmeraldas crustal faults define a ∼200-km-long margin crustal block that coincides with the 1942 earthquake rupture zone. Subduction of the buoyant Carnegie Ridge is inferred to partially lock the plate interface along central Ecuador. However, coseismic slip during the 1942 and 1906 earthquakes may have terminated against the subducted northern flank of the ridge. We report on a newly identified Manglares crustal fault that cuts transversally through the margin wedge and correlates with the limit between the 1958 and 1979 rupture zones. During the earthquake cycle the fault is associated with high-stress concentration on the plate interface. An outer basement high, which bounds the margin seaward of the 1958 rupture zone, may act as a deformable buttress to seaward propagation of coseismic slip along a megathrust splay fault. Coseismic uplift of the basement high is interpreted as the cause for the 1958 tsunami. We propose a model of weak transverse faults which reduce coupling between adjacent margin segments, together with a splay fault and an asperity along the plate interface as controlling the seismogenic rupture of the 1958 earthquake.

Facultad de Geología y Petróleos

BIGP Donación 2010/12/17 25228 $ 0.10 Ej. 1 Biblioteca Facultad de Geología y Petróleos

There are no comments on this title.

to post a comment.
Share

Powered by Koha