Structural architecture of oceanic plateau subduction offshore Eastern Java and the potential implications for geohazards.

Shulgin, Alexey, Kopp, Heidrun , Mueller, C., Planert, Lars, Lueschen, E., Flueh, E. R. and Djajadihardja, Y. (2011) Structural architecture of oceanic plateau subduction offshore Eastern Java and the potential implications for geohazards. Open Access Geophysical Journal International, 184 . pp. 12-28. DOI 10.1111/j.1365-246X.2010.04834.x.

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Abstract

The region offshore Eastern Java represents one of the few places where the early stage of oceanic plateau subduction is occurring. We study the little investigated Roo Rise oceanic plateau on the Indian plate, subducting beneath Eurasia. The presence of the abnormal bathymetric features entering the trench has a strong effect on the evolution of the subduction system, and causes additional challenges on the assessment of geohazard risks. We present integrated results of a refraction/wide-angle reflection tomography, gravity modelling, and multichannel reflection seismic imaging using data acquired in 2006 south of Java near 113°E. The composite structural model reveals the previously unresolved deep geometry of the oceanic plateau and the subduction zone. The oceanic plateau crust is on average 15 km thick and covers an area of about 100 000 km2. Within our profile the Roo Rise crustal thickness ranges between 18 and 12 km. The upper oceanic crust shows high degree of fracturing, suggesting heavy faulting. The forearc crust has an average thickness of 14 km, with a sharp increase to 33 km towards Java, as revealed by gravity modelling. The complex geometry of the backstop suggests two possible models for the structural formation within this segment of the margin: either accumulation of the Roo Rise crustal fragments above the backstop or alternatively uplift of the backstop caused by basal accumulation of crustal fragments. The subducting plateau is affecting the stress field within the accretionary complex and the backstop edge, which favours the initiation of large, potentially tsunamogenic earthquakes such as the 1994 Mw= 7.8 tsunamogenic event.

Document Type: Article
Additional Information: This article has been published in Geophysical Journal International ©2011 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Keywords: Geodynamics; Tomography; Subduction zone processes; Oceanic plateaus and microcontinents; Crustal structure; Asia
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1111/j.1365-246X.2010.04834.x
ISSN: 0956-540X
Projects: Future Ocean
Date Deposited: 23 Nov 2010 10:01
Last Modified: 10 Jul 2018 09:47
URI: http://oceanrep.geomar.de/id/eprint/10092

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