Skip to Main content Skip to Navigation
Journal articles

Seismic Evidence for Fluid/Gas Beneath the Mentawai Fore-Arc Basin, Central Sumatra

Abstract : Since 2004, there have been three great interplate earthquakes (Mw > 8.0) offshore Sumatra. In addition to rupturing the megathrust, these earthquakes might also have ruptured the backthrusts that bound the Andaman Islands to the Mentawai Islands toward the forearc basins. Here we apply a combination of traveltime tomography and seismic full waveform inversion to an ultralong offset seismic reflection profile from the Mentawai forearc basin, in the region of the 2007 Mw 8.4 Bengkulu earthquake. We perform a waveform inversion of far-offset data followed by a waveform inversion of near-offset data using the starting model derived from the traveltime tomography. Our results show the presence of a large, low-velocity anomaly above the backthrust. The seismic reflection image indicates that this low-velocity anomaly lies either within highly compacted sediments from the accretionary wedge or within highly deformed sediments from the forearc basin. The porosity estimation, using the effective medium theory, suggests that a small amount of gas (from 2 to 13%) or a significant amount of fluid (from 17 to 40%) could generate this low-velocity zone. The presence of fluids and the observation of bottom simulating reflector below a push-up ridge might be associated with mud diapirism. The fluids could originate locally from the dewatering of the sediments from the accretionary wedge or forearc basin. The high reflectivity of the backthrust in this region might also indicate deeper fluid origin, either from underplated sediments on the subduction interface or from the serpentinized mantle wedge.
Document type :
Journal articles
Complete list of metadata

https://hal-insu.archives-ouvertes.fr/insu-03589377
Contributor : Nathalie POTHIER Connect in order to contact the contributor
Submitted on : Friday, February 25, 2022 - 3:55:26 PM
Last modification on : Sunday, February 27, 2022 - 3:08:32 AM
Long-term archiving on: : Thursday, May 26, 2022 - 7:50:45 PM

File

JGR Solid Earth - 2018 - Huot ...
Publisher files allowed on an open archive

Licence

Copyright

Identifiers

Collections

Citation

Gabriel Huot, Satish C. Singh. Seismic Evidence for Fluid/Gas Beneath the Mentawai Fore-Arc Basin, Central Sumatra. Journal of Geophysical Research : Solid Earth, American Geophysical Union, 2018, 123, pp.957-976. ⟨10.1002/2017JB014849⟩. ⟨insu-03589377⟩

Share

Metrics

Record views

29

Files downloads

12