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The 2010 Mw 8.8 Maule, Chile earthquake: Nucleation and rupture propagation controlled by a subducted topographic high

The 2010 Mw 8.8 Maule, Chile earthquake: Nucleation and rupture propagation controlled by a subducted topographic high
The 2010 Mw 8.8 Maule, Chile earthquake: Nucleation and rupture propagation controlled by a subducted topographic high
Knowledge of seismic properties in an earthquake rupture zone is essential for understanding the factors controlling rupture dynamics. We use data from aftershocks following the Maule earthquake to derive a three-dimensional seismic velocity model of the central Chile forearc. At 36°S, we find a highvp (>7.0 km/s) and high vp/vs(?1.89) anomaly lying along the megathrust at 25 km depth, which coincides with a strong forearc Bouguer gravity signal. We interpret this as a subducted topographic high, possibly a former seamount on the Nazca slab. The Maule earthquake nucleated at the anomaly's updip boundary; yet high co-seismic slip occurred where the megathrust is overlain by lower seismic velocities. Sparse aftershock seismicity occurs within this structure, suggesting that it disrupts normal interface seismogenesis. These findings imply that subducted structures can be conducive to the nucleation of large megathrust earthquakes, even if they subsequently hinder co-seismic slip and aftershock activity.
Maule, earthquake, megathrust, seamount
0094-8276
L19308
Hicks, Stephen P.
036d1b3b-bb7a-4a22-b2ce-71618a1723a3
Rietbrock, Andreas
e4656f22-06be-40fe-8f98-7f88c351c434
Haberland, Christian A.
c108fb90-ff99-4f8a-9606-44ebcd1fbc90
Ryder, Isabelle M.A.
e4db9c08-f27a-41a8-bbcc-0b6f9c472aad
Simons, Mark
6dda0d9f-cd72-419f-8897-622995a2f2f5
Tassara, Andrés
b68fe328-f548-47da-b5c7-3b91744d0a64
Hicks, Stephen P.
036d1b3b-bb7a-4a22-b2ce-71618a1723a3
Rietbrock, Andreas
e4656f22-06be-40fe-8f98-7f88c351c434
Haberland, Christian A.
c108fb90-ff99-4f8a-9606-44ebcd1fbc90
Ryder, Isabelle M.A.
e4db9c08-f27a-41a8-bbcc-0b6f9c472aad
Simons, Mark
6dda0d9f-cd72-419f-8897-622995a2f2f5
Tassara, Andrés
b68fe328-f548-47da-b5c7-3b91744d0a64

Hicks, Stephen P., Rietbrock, Andreas, Haberland, Christian A., Ryder, Isabelle M.A., Simons, Mark and Tassara, Andrés (2012) The 2010 Mw 8.8 Maule, Chile earthquake: Nucleation and rupture propagation controlled by a subducted topographic high. Geophysical Research Letters, 39 (19), L19308. (doi:10.1029/2012GL053184).

Record type: Article

Abstract

Knowledge of seismic properties in an earthquake rupture zone is essential for understanding the factors controlling rupture dynamics. We use data from aftershocks following the Maule earthquake to derive a three-dimensional seismic velocity model of the central Chile forearc. At 36°S, we find a highvp (>7.0 km/s) and high vp/vs(?1.89) anomaly lying along the megathrust at 25 km depth, which coincides with a strong forearc Bouguer gravity signal. We interpret this as a subducted topographic high, possibly a former seamount on the Nazca slab. The Maule earthquake nucleated at the anomaly's updip boundary; yet high co-seismic slip occurred where the megathrust is overlain by lower seismic velocities. Sparse aftershock seismicity occurs within this structure, suggesting that it disrupts normal interface seismogenesis. These findings imply that subducted structures can be conducive to the nucleation of large megathrust earthquakes, even if they subsequently hinder co-seismic slip and aftershock activity.

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Accepted/In Press date: 14 September 2012
Published date: 1 October 2012
Keywords: Maule, earthquake, megathrust, seamount
Organisations: Ocean and Earth Science, Geology & Geophysics

Identifiers

Local EPrints ID: 405576
URI: http://eprints.soton.ac.uk/id/eprint/405576
ISSN: 0094-8276
PURE UUID: a4d3ad0a-47db-43c3-8e71-ae51bac125a3
ORCID for Stephen P. Hicks: ORCID iD orcid.org/0000-0002-7476-3284

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Date deposited: 06 Feb 2017 14:54
Last modified: 07 Jan 2022 21:57

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Contributors

Author: Stephen P. Hicks ORCID iD
Author: Andreas Rietbrock
Author: Christian A. Haberland
Author: Isabelle M.A. Ryder
Author: Mark Simons
Author: Andrés Tassara

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