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Downgoing plate topography stopped rupture in the A.D. 2005 Sumatra earthquake

Downgoing plate topography stopped rupture in the A.D. 2005 Sumatra earthquake
Downgoing plate topography stopped rupture in the A.D. 2005 Sumatra earthquake
Earthquakes in subduction zones rupture the plate boundary fault in discrete segments. One factor that may control this segmentation is topography on the downgoing plate, although it is controversial whether this is by weakening or strengthening of the fault. We use multichannel seismic and gravity data to map the top of the downgoing oceanic crust offshore central Sumatra, Indonesia. Our survey spans a complex segment boundary zone between the southern termination of the Mw = 8.7, A.D. 2005 Simeulue-Nias earthquake, and the northern termination of a major 1797 earthquake that was partly filled by an Mw = 7.7 event in 1935. We identify an isolated 3 km basement high at the northern edge of this zone, close to the 2005 slip termination. The high probably originated at the Wharton fossil ridge, and is almost aseismic in both local and global data sets, suggesting that while the region around it may be weakened by fracturing and fluids, the basement high locally strengthens the plate boundary, stopping rupture propagation.
0091-7613
71-74
Henstock, Timothy
27c450a4-3e6b-41f8-97f9-4e0e181400bb
McNeill, Lisa
1fe6a1e0-ca1a-4b6f-8469-309d0f9de0cf
Bull, Jonathan
974037fd-544b-458f-98cc-ce8eca89e3c8
Cook, Becky
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Gulick, Sean
fe24f7ed-8894-4364-9ec0-81c5e3a4ef35
Austin, James
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Permana, Haryadi
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Djajadihardja, Yusuf
59ea8415-8a8c-4c34-b480-bc7e064a53f7
Henstock, Timothy
27c450a4-3e6b-41f8-97f9-4e0e181400bb
McNeill, Lisa
1fe6a1e0-ca1a-4b6f-8469-309d0f9de0cf
Bull, Jonathan
974037fd-544b-458f-98cc-ce8eca89e3c8
Cook, Becky
bfa0ce44-76b1-419e-979a-d84c23266579
Gulick, Sean
fe24f7ed-8894-4364-9ec0-81c5e3a4ef35
Austin, James
90ed56d3-90bf-4283-b3fa-33631db85a03
Permana, Haryadi
b5f42881-f590-449e-b718-506ee3a1d1c8
Djajadihardja, Yusuf
59ea8415-8a8c-4c34-b480-bc7e064a53f7

Henstock, Timothy, McNeill, Lisa, Bull, Jonathan, Cook, Becky, Gulick, Sean, Austin, James, Permana, Haryadi and Djajadihardja, Yusuf (2016) Downgoing plate topography stopped rupture in the A.D. 2005 Sumatra earthquake. Geology, 44 (1), 71-74. (doi:10.1130/G37258.1).

Record type: Article

Abstract

Earthquakes in subduction zones rupture the plate boundary fault in discrete segments. One factor that may control this segmentation is topography on the downgoing plate, although it is controversial whether this is by weakening or strengthening of the fault. We use multichannel seismic and gravity data to map the top of the downgoing oceanic crust offshore central Sumatra, Indonesia. Our survey spans a complex segment boundary zone between the southern termination of the Mw = 8.7, A.D. 2005 Simeulue-Nias earthquake, and the northern termination of a major 1797 earthquake that was partly filled by an Mw = 7.7 event in 1935. We identify an isolated 3 km basement high at the northern edge of this zone, close to the 2005 slip termination. The high probably originated at the Wharton fossil ridge, and is almost aseismic in both local and global data sets, suggesting that while the region around it may be weakened by fracturing and fluids, the basement high locally strengthens the plate boundary, stopping rupture propagation.

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Accepted/In Press date: 23 November 2015
e-pub ahead of print date: 4 December 2015
Published date: January 2016
Organisations: Geology & Geophysics

Identifiers

Local EPrints ID: 384982
URI: http://eprints.soton.ac.uk/id/eprint/384982
ISSN: 0091-7613
PURE UUID: 196161d8-66bc-47b5-920f-efff3dc2648d
ORCID for Timothy Henstock: ORCID iD orcid.org/0000-0002-2132-2514
ORCID for Lisa McNeill: ORCID iD orcid.org/0000-0002-8689-5882
ORCID for Jonathan Bull: ORCID iD orcid.org/0000-0003-3373-5807

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Date deposited: 14 Dec 2015 17:30
Last modified: 15 Mar 2024 03:09

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Contributors

Author: Lisa McNeill ORCID iD
Author: Jonathan Bull ORCID iD
Author: Becky Cook
Author: Sean Gulick
Author: James Austin
Author: Haryadi Permana
Author: Yusuf Djajadihardja

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