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Published October 13, 2012 | Published + Supplemental Material
Journal Article Open

The 2010 M_w 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 high v_p (>7.0 km/s) and high v_p/v_s (∼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.

Additional Information

© 2012 American Geophysical Union. Received 24 July 2012; accepted 14 September 2012; published 13 October 2012. We thank IRIS, CNRS-INSU, GFZ, and Caltech for making continuous waveform data available. The complete IMAD data set can be accessed through the IRIS and GFZ data centers (http://www.iris.edu/dms/dmc/, http://webdc.eu/). Support in the field was given by the Seismological Service National of Chile, the Universidad of Concepción, and the University de Santiago de Chile. We are grateful to all field crews from partner organizations who participated in the deployment; without this combined effort, we would not have such a large and comprehensive data set. In support of this deployment we received funding from NERC (grant NE/I005420/1). Seismic instruments were provided by CNRS-INSU, IRIS/PASSCAL, GIPP(GFZ), GEF/SEIS-UK. We are grateful to two anonymous reviewers for providing insightful comments and suggestions, which have improved the manuscript. S.P.H. is funded by a NERC studentship. A.T. acknowledges support of Fondecyt project 1101034. We thank Kay Lancaster for assistance with producing Figure 4. [16] The Editor thanks two anonymous reviewers for their assistance in evaluating this paper.

Attached Files

Published - 2012GL053184.pdf

Supplemental Material - 2012gl053184-fs01.jpg

Supplemental Material - 2012gl053184-fs02.jpg

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Supplemental Material - 2012gl053184-txts01.txt

Supplemental Material - 2012gl053184-txts02.txt


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August 22, 2023
October 20, 2023