New insights on co- and post-seismic deformation and slip behavior associated with the Mw7.8 2016 Pedernales, Ecuador earthquake and its aftershock sequence
Abstract
On April 16, 2016, a Mw7.8 earthquake, associated with oblique subduction of the Nazca Plate under South America, ruptured a segment approximately 130x100km in the region north of the intersection of the Carnegie ridge with the Ecuador subduction zone. The rupture coincides with the rupture area of the Mw7.8 1942 earthquake. To characterize the aftershock sequence, we analyze seismic data recorded by 30 stations from April 17, 2016 to May 8, 2017; 11 stations belong to Ecuador's national network and 19 are part of a PASSCAL temporary deployment. We apply a kurtosis detector to obtain automatic P- and S-wave picks. Earthquake locations, magnitudes, and regional moment tensors are obtained using the U.S. Geological Survey National Earthquake Information Center (NEIC) processing system. We also determine calibrated relocations using the Hypocentroidal Decomposition approach for a subset of events for which we combine phase readings from local and temporary PASSCAL stations with regional and teleseismic phase readings from the NEIC. In contrast with other earthquake relocation approaches, this method evaluates absolute location uncertainties for each event in the cluster, which allows us to more confidently assess the relationships between mainshock slip and aftershock activity. We find the aftershock sequence is characterized by a series of event clusters that predominantly surround the main rupture patches. However, the aftershocks extend beyond the mainshock rupture area, covering a region approximately 250x100km. Aftershocks north of the 2016 rupture fall in the rupture area of the Mw7.7 1958 earthquake. The southernmost region of elevated seismicity occurs south of a region of low coupling where the Carnegie ridge meets the subduction zone. The characterization of this sequence allows a detailed spatial and temporal analysis of the rupture processes, stress patterns and slip behavior during this earthquake sequence in Ecuador subduction zone.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.S53C0715S
- Keywords:
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- 1209 Tectonic deformation;
- GEODESY AND GRAVITY;
- 4302 Geological;
- NATURAL HAZARDS;
- 7215 Earthquake source observations;
- SEISMOLOGY;
- 8123 Dynamics: seismotectonics;
- TECTONOPHYSICS