New insights on the offshore extension of the Great Sumatran fault, NW Sumatra, from marine geophysical studies

Ghosal, Dibakar; Singh, S. C.; Chauhan, A.; Hananto, Nugroho D.

doi:10.1029/2012gc004122

Cited by 39 publications

(40 citation statements)

References 74 publications

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“…On the other hand, Quaternary sediments primarily consist of sag fill deposits in the AFB. Our interpretation has brought out a stratigraphic framework within the AFB, which compliments similar studies (e.g., Ghosal et al 2012;Singh et al 2013;Moeremans and Singh 2015) published from the southern segment of the Andaman-Sumatra subduction system. The accretionary prism in the region contains several weak zones that could be potential rupture targets in the event of large earthquakes.…”

Section: Resultssupporting

confidence: 87%

“…The relocation of the volcanic arc from the Megui ridge ( Fig. 1) further west finally led to the extension in the Megui Basin in the late Oligocene (Ghosal et al 2012;Moeremans and Singh 2015). The entire Andaman Basin is * 1200 km long and extends from the Irrawaddy delta coast of Myanmar in the north to the Sunda trench in the south with a maximum E-W stretch of * 600 km (Fig.…”

Section: Introductionmentioning

confidence: 98%

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Late Cenozoic seismic stratigraphy of the Andaman Forearc Basin, Indian Ocean

et al. 2017

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Interpretation of new multichannel seismic reflection data from the Andaman Forearc Basin (AFB) in the northern Indian Ocean is presented here. The highquality multichannel seismic data from the Andaman Forearc region enable us to examine the seismic characters and to demarcate seismic sequences bounded by distinct unconformities. Ages of marked seismic horizons have been calibrated with available litholog data from nearby industry boreholes. Seismic interpretation of new data shows that the AFB is filled with * 4.5-s-two way travel time (TWT) thick Neogene to Recent sediments. The entire basin assemblage exhibits two distinct major sequences pertaining to the Neogene and Quaternary times. A large part of the basin is filled with intermittent mass transport deposits (MTD). We infer that the episodic uplift of the Invisible Bank, protuberance of the outerarc and regular deformation through reactivation of preexisting normal faults since the Pleistocene could be attributed as causal mechanisms for the MTDs. Strong bottom simulating reflectors are identified in the Late Miocene and younger sediments of the outerarc and AFB at a depth of * 0.6 s TWT and correspond to the presence of gas hydrates in this region. Our interpretations have significant implications for geodynamic as well as resource exploration in the AFB.

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Section: Resultssupporting

confidence: 87%

Section: Introductionmentioning

confidence: 98%

Late Cenozoic seismic stratigraphy of the Andaman Forearc Basin, Indian Ocean

et al. 2017

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“…As it enters the Andaman Sea near Banda Aceh, the Great Sumatra Fault divides into two strands: the Aceh fault in the west and the Seulimeum fault in the east. Ghosal et al (2012) have found that the Aceh strand is the most seismically active branch. The strike of these faults is the same as that of the GSF, that is, NW.…”

Section: The Andaman -Nicobar Faultmentioning

confidence: 99%

Chapter 13 Anatomy of the Andaman–Nicobar subduction system from seismic reflection data

Singh¹,

Moeremans²

2017

Memoirs

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The Andaman–Nicobar subduction system is the northwestern segment of the Sunda subduction system, where the Indian Plate subducts beneath the Sunda Plate in a nearly arc-parallel direction. The entire segment ruptured during the 2004 great Andaman–Sumatra earthquake (Mw=9.3). Using recently acquired high-resolution seismic reflection data, we characterize the shallow structure of the whole Andaman–Nicobar subduction system from west to east, starting from the nature of the subducting plate in the Bay of Bengal to back-arc spreading in the Andaman Sea. We find that the Ninety-East Ridge is overlain by thick continental margin sediments beneath the recent Bengal Fan sediments. The boundary between these two sedimentary units defines the plate interface. We observe evidence of re-activation of fracture zones on the subducting plate beneath the forearc, influencing the morphology of the upper plate. The forearc region, which includes the accretionary wedge, the forearc high and the forearc basin, is exceptionally wide (250 km). We observe an unusually large bathymetric depression within the forearc high. The forearc high is bounded in the east by a normal fault, whereas the forearc basin contains an active backthrust. The forearc basin is floored by the continental crust of Malayan Peninsula origin. The active sliver strike-slip fault lies in a deep basin, created during the rifting of the forearc continental crust and the Malayan Peninsula. The sliver fault connects with the Great Sumatra Fault in the south and with the Sagaing Fault in the north, via the Andaman Sea spreading centre and a large transform fault in the Andaman Sea.

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“…Ghosal et al . [] suggest that this arc shifts farther northward in a pull‐apart basin whereas the main active strand of the GSF follows the Aceh Fault strand.…”

Section: Tectonic Settingmentioning

confidence: 99%

Seismic images of the sliver strike‐slip fault and back thrust in the Andaman‐Nicobar region

Singh

Moeremans

McArdle³

et al. 2013

JGR Solid Earth

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The sliver strike‐slip Great Sumatra Fault (GSF) traverses mainland Sumatra from the Sunda Strait in the southeast to Banda Aceh in the northwest, and defines the present day plate boundary between the Sunda Plate in the north and the Burmese Sliver Plate in the south. It has been well studied on mainland Sumatra but poorly north of Banda Aceh in the Andaman Sea. Here we present deep seismic reflection images along the northward extension of the GSF over 700 km until it joins the Andaman Sea Spreading Centre, and we interpret these images in the light of earthquake, gravity, and bathymetry data. We find that the GSF has two strands between Banda Aceh and Nicobar Island: a transpression in the south and a deep narrow active rift system in the north, dotted with volcanoes in the center, suggesting that the volcanic arc is coincident with rifting. Farther north of Nicobar Island, an active strike‐slip fault, the Andaman‐Nicobar Fault, cuts through a rifted deep basin until its intersection with the Andaman Sea Spreading Centre. The volcanic arc lies just east of the rift basin. The western margin of this basin seems to be a rifted continental margin, tilted westward, and flooring the Andaman‐Nicobar fore‐arc basin. The Andaman‐Nicobar fore‐arc basin is bounded in the west by back thrusts similar to the West Andaman and Mentawai faults. The cluster of seismicity after the 2004 great Andaman‐Sumatra earthquake just north of Nicobar Island coincides with the intersection of two strike‐slip fault systems.

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New insights on the offshore extension of the Great Sumatran fault, NW Sumatra, from marine geophysical studies

Cited by 39 publications

References 74 publications

Late Cenozoic seismic stratigraphy of the Andaman Forearc Basin, Indian Ocean

Late Cenozoic seismic stratigraphy of the Andaman Forearc Basin, Indian Ocean

Chapter 13 Anatomy of the Andaman–Nicobar subduction system from seismic reflection data

Seismic images of the sliver strike‐slip fault and back thrust in the Andaman‐Nicobar region

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