Stratigraphic control of frontal décollement level and structural vergence and implications for tsunamigenic earthquake hazard in Sumatra, Indonesia

Propagation of fault rupture to the seafloor is a likely cause of enhanced tsunami generation during megathrust earthquakes. New, high‐resolution seismic reflection profiles and swath bathymetry collected across the northern limit of the Mw 7.8, 25 October 2010 Mentawai tsunami earthquake rupture re...

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Main Authors: Bradley, Kyle, Qin, Yanfang, Carton, Hélène, Hananto, Nugroho, Villanueva‐Robles, Fernando, Leclerc, Fréderique, Shengji, Wei, Tapponier, Paul, Sieh, Kerry, Singh, Satish
Other Authors: Asian School of the Environment
Format: Article
Language:English
Published: 2019
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Online Access:https://hdl.handle.net/10356/105938
http://hdl.handle.net/10220/48785
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1059382020-09-26T21:32:29Z Stratigraphic control of frontal décollement level and structural vergence and implications for tsunamigenic earthquake hazard in Sumatra, Indonesia Bradley, Kyle Qin, Yanfang Carton, Hélène Hananto, Nugroho Villanueva‐Robles, Fernando Leclerc, Fréderique Shengji, Wei Tapponier, Paul Sieh, Kerry Singh, Satish Asian School of the Environment Earth Observatory of Singapore Tsunami DRNTU::Science::Geology Subduction Propagation of fault rupture to the seafloor is a likely cause of enhanced tsunami generation during megathrust earthquakes. New, high‐resolution seismic reflection profiles and swath bathymetry collected across the northern limit of the Mw 7.8, 25 October 2010 Mentawai tsunami earthquake rupture reveal significant and systematic lateral variations in both the stratigraphic level of the frontal Sunda megathrust and the vergence of its frontal ramp faults. Where ramp faults are uniformly seaward vergent, the décollement resides on top of a strong reflector marking the inferred top of pelagic sediments. Where ramp faults are bivergent (both landward and seaward), the décollement is localized within the subducting clastic sequence, above a xseismically transparent unit inferred to be distal fan muds. Where ramp faults are uniformly landward vergent, the décollement is directly on top of the oceanic crust of the subducting Investigator Fracture Zone. Enhanced surface uplift and tsunamigenesis during the 2010 tsunamigenic earthquake appear to have coincided with propagation of rupture into frontal areas with well‐developed structural bivergence. Frontal bivergence is a geological signal of low basal traction during accrual of slip, and offshore of Sumatra this structural style may mark areas of enhanced tsunami hazard posed by small‐magnitude, shallow megathrust ruptures that propagate into the incoming terrigenous sequence at near‐trench levels. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Published version 2019-06-18T01:51:36Z 2019-12-06T22:01:08Z 2019-06-18T01:51:36Z 2019-12-06T22:01:08Z 2019 Journal Article Bradley, K., Qin, Y., Carton, H., Hananto, N., Villanueva‐Robles, F., Leclerc, F., . . . Singh, S. (2019). Stratigraphic control of frontal décollement level and structural vergence and implications for tsunamigenic earthquake hazard in Sumatra, Indonesia. Geochemistry, Geophysics, Geosystems, 20(3), 1646-1664. doi:10.1029/2018GC008025 https://hdl.handle.net/10356/105938 http://hdl.handle.net/10220/48785 10.1029/2018GC008025 en Geochemistry, Geophysics, Geosystems © 2019 The Authors. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made. 19 p. application/pdf
institution Nanyang Technological University
building NTU Library
country Singapore
collection DR-NTU
language English
topic Tsunami
DRNTU::Science::Geology
Subduction
spellingShingle Tsunami
DRNTU::Science::Geology
Subduction
Bradley, Kyle
Qin, Yanfang
Carton, Hélène
Hananto, Nugroho
Villanueva‐Robles, Fernando
Leclerc, Fréderique
Shengji, Wei
Tapponier, Paul
Sieh, Kerry
Singh, Satish
Stratigraphic control of frontal décollement level and structural vergence and implications for tsunamigenic earthquake hazard in Sumatra, Indonesia
description Propagation of fault rupture to the seafloor is a likely cause of enhanced tsunami generation during megathrust earthquakes. New, high‐resolution seismic reflection profiles and swath bathymetry collected across the northern limit of the Mw 7.8, 25 October 2010 Mentawai tsunami earthquake rupture reveal significant and systematic lateral variations in both the stratigraphic level of the frontal Sunda megathrust and the vergence of its frontal ramp faults. Where ramp faults are uniformly seaward vergent, the décollement resides on top of a strong reflector marking the inferred top of pelagic sediments. Where ramp faults are bivergent (both landward and seaward), the décollement is localized within the subducting clastic sequence, above a xseismically transparent unit inferred to be distal fan muds. Where ramp faults are uniformly landward vergent, the décollement is directly on top of the oceanic crust of the subducting Investigator Fracture Zone. Enhanced surface uplift and tsunamigenesis during the 2010 tsunamigenic earthquake appear to have coincided with propagation of rupture into frontal areas with well‐developed structural bivergence. Frontal bivergence is a geological signal of low basal traction during accrual of slip, and offshore of Sumatra this structural style may mark areas of enhanced tsunami hazard posed by small‐magnitude, shallow megathrust ruptures that propagate into the incoming terrigenous sequence at near‐trench levels.
author2 Asian School of the Environment
author_facet Asian School of the Environment
Bradley, Kyle
Qin, Yanfang
Carton, Hélène
Hananto, Nugroho
Villanueva‐Robles, Fernando
Leclerc, Fréderique
Shengji, Wei
Tapponier, Paul
Sieh, Kerry
Singh, Satish
format Article
author Bradley, Kyle
Qin, Yanfang
Carton, Hélène
Hananto, Nugroho
Villanueva‐Robles, Fernando
Leclerc, Fréderique
Shengji, Wei
Tapponier, Paul
Sieh, Kerry
Singh, Satish
author_sort Bradley, Kyle
title Stratigraphic control of frontal décollement level and structural vergence and implications for tsunamigenic earthquake hazard in Sumatra, Indonesia
title_short Stratigraphic control of frontal décollement level and structural vergence and implications for tsunamigenic earthquake hazard in Sumatra, Indonesia
title_full Stratigraphic control of frontal décollement level and structural vergence and implications for tsunamigenic earthquake hazard in Sumatra, Indonesia
title_fullStr Stratigraphic control of frontal décollement level and structural vergence and implications for tsunamigenic earthquake hazard in Sumatra, Indonesia
title_full_unstemmed Stratigraphic control of frontal décollement level and structural vergence and implications for tsunamigenic earthquake hazard in Sumatra, Indonesia
title_sort stratigraphic control of frontal décollement level and structural vergence and implications for tsunamigenic earthquake hazard in sumatra, indonesia
publishDate 2019
url https://hdl.handle.net/10356/105938
http://hdl.handle.net/10220/48785
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