Abstract
Aftershocks of the 2012 Off-Coast of Sumatra Earthquake Sequence exhibit a complex and diffuse spatial distribution. The first-order complexity in aftershock distribution is clear and well beyond the influence of typical earthquake location uncertainty. The sequence included rupture of multiple fault segments, spatially separated. We use surface-wave based relative centroid locations to examine whether, at the small scale, the distribution of the aftershocks was influenced by location errors. Surface-wave based relative location has delineated precise oceanic transform fault earthquake locations in multiple regions. However, the relocated aftershocks off the coast of Sumatra seldom align along simple linear trends that are compatible with the corresponding fault strikes as estimated for the GCMT catalog. The relocation of roughly 60 moderate-earthquake epicentroids suggests that the faulting involved in the 2012 earthquake aftershock sequence included strain release along many short fault segments. Statistical analysis and temporal variations of aftershocks show a typical decay of the aftershocks but a relatively low number of aftershocks, as is common for intraplate oceanic earthquakes. Coulomb stress calculations indicate that most of the moderate-magnitude aftershocks are compatible with stress changes predicted by the large-event slip models. The patterns in the aftershocks suggest that the formation of the boundary and eventual localization of deformation between the Indian and Australian plate is a complicated process.
| Original language | English |
|---|---|
| Pages (from-to) | 61-72 |
| Number of pages | 12 |
| Journal | Tectonophysics |
| Volume | 763 |
| DOIs | |
| State | Published - Jul 20 2019 |
| Externally published | Yes |
Funding
This work was supported by the Defense Threat Reduction Agency under Award HDTRA1-11-1-0027 . This material is based upon work partially supported by the U.S. Department of Energy , Office of Science, under contract number DE-AC05-00OR22725 . The facilities of IRIS Data Services, and specifically the IRIS Data Management Center, were used for access the waveforms, related metadata, and/or derived products used in this study. IRIS Data Services are funded through the Seismological Facilities for the Advancement of Geoscience and EarthScope (SAGE) Proposal of the National Science Foundation under Cooperative Agreement EAR-1261681. The authors thank Monica Maceira and Philip Bingham for helpful comments. We acknowledge developers of Generic Mapping Tools ( Wessel et al., 2013 ), Obspy ( Beyreuther et al., 2010 ; Krischer et al., 2015 ; Megies et al., 2011 ), Numpy ( van der Walt et al., 2011 ), and Matplotlib ( Hunter, 2007 ) for sharing their packages. We also thank University of California San Diego for sharing the STRM15 topography data that were used as the background for several figures. This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). We thank an anonymous review and the Editor Rob Govers for constructive comments and suggestions.
| Funders | Funder number |
|---|---|
| US Department of Energy | |
| National Science Foundation | EAR-1261681 |
| U.S. Department of Energy | |
| Directorate for Geosciences | 1261681 |
| Defense Threat Reduction Agency | HDTRA1-11-1-0027 |
| Office of Science | DE-AC05-00OR22725 |
Keywords
- 2012 Sumatra Earthquake
- Aftershock analysis
- Coulomb stress
- Earthquake relocation
