Systematic Changes of Earthquake Rupture with Depth: A Case Study from the 2010Mw 8.8 Maule, Chile, Earthquake Aftershock Sequence

Sen, Ali Tolga, Cesca, Simone, Lange, Dietrich, Dahm, Torsten, Tilmann, Frederik and Heimann, Sebastian (2015) Systematic Changes of Earthquake Rupture with Depth: A Case Study from the 2010Mw 8.8 Maule, Chile, Earthquake Aftershock Sequence Bulletin of the Seismological Society of America, 105 (5). pp. 2468-2479. DOI 10.1785/0120140123.

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The very shallow part of subduction megathrusts occasionally hosts tsunami earthquakes, with unusually slow rupture propagation. The aftershock sequence of the 2010 Mw 8.8 Maule earthquake, offshore Chile, provides us with the opportunity to study systematic changes in source properties for smaller earthquakes within a single segment of a subduction zone. We invert amplitude spectra for double-couple moment tensors and centroid depths of 71 aftershocks of the Maule earthquake down to magnitudes Mw 4.0. In addition, we also derive average source durations.We find that shallower earthquakes tend to have longer normalized source durations on average, similar to the pattern observed previously for larger magnitude events. This depth dependence is observable for thrust and normal earthquakes. The normalized source durations of normal- faulting earthquakes are at the lower end of those for thrust earthquakes, probably because of the higher stress drops of intraplate earthquakes compared to interplate earthquakes. We suggest from the similarity of the depth dependence of normal and thrust events and between smaller and larger magnitude earthquakes that the depth-dependent variation of rigidity, rather than frictional conditional stability at the plate interface, is primarily responsible for the observed pattern. Tsunami earthquakes probably require both low rigidity and conditionally stable frictional conditions; the presence of longduration moderate-magnitude events is therefore a helpful but not sufficient indicator for areas at risk of tsunami earthquakes.

Document Type: Article
Additional Information: WOS:000362122600011
Keywords: Aftershock sequence; Chile; Table of earthquake inversion results for the 2010Mw 8.8 Maule
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
DOI etc.: 10.1785/0120140123
ISSN: 0037-1106
Projects: MARISCOS
Date Deposited: 16 Oct 2015 12:11
Last Modified: 29 Jun 2017 13:03

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