Anatomy of the western Java plate interface from depth-migrated seismic images.

Kopp, Heidrun , Hindle, David, Klaeschen, Dirk , Oncken, O. and Scholl, D. (2009) Anatomy of the western Java plate interface from depth-migrated seismic images. Earth and Planetary Science Letters, 288 (3-4). pp. 399-407. DOI 10.1016/j.epsl.2009.09.043.

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Newly pre-stack depth-migrated seismic images resolve the structural details of the western Java forearc and plate interface. The structural segmentation of the forearc into discrete mechanical domains correlates with distinct deformation styles. Approximately 2/3 of the trench sediment fill is detached and incorporated into frontal prism imbricates, while the floor sequence is underthrust beneath the décollement. Western Java, however, differs markedly from margins such as Nankai or Barbados, where a uniform, continuous décollement reflector has been imaged. In our study area, the plate interface reveals a spatially irregular, nonlinear pattern characterized by the morphological relief of subducted seamounts and thicker than average patches of underthrust sediment. The underthrust sediment is associated with a low velocity zone as determined from wide-angle data. Active underplating is not resolved, but likely contributes to the uplift of the large bivergent wedge that constitutes the forearc high. Our profile is located 100 km west of the 2006 Java tsunami earthquake. The heterogeneous décollement zone regulates the friction behavior of the shallow subduction environment where the earthquake occurred. The alternating pattern of enhanced frictional contact zones associated with oceanic basement relief and weak material patches of underthrust sediment influences seismic coupling and possibly contributed to the heterogeneous slip distribution. Our seismic images resolve a steeply dipping splay fault, which originates at the décollement and terminates at the sea floor and which potentially contributes to tsunami generation during co-seismic activity.

Document Type: Article
Keywords: Décollement, splay fault, prestack depth migration, Subduction zone, tsunami earthquake, Indonesia
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
Publisher: Elsevier
Projects: Future Ocean
Date Deposited: 27 Jan 2010 15:32
Last Modified: 09 Feb 2017 11:04

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