Investigating Potential Earthquake Preparatory Phase From Short-Term and Long-Term Seismic Observations
Session: New Insights Into the Preparatory Phase of Earthquakes From Tectonic, Field and Lab Experiments II
Type: Oral
Date: 4/19/2021
Presentation Time: 02:15 PM Pacific
Description:
Predicting the timing and location of an upcoming hazardous earthquake has been the ultimate goal in the seismological community. Although it’s nearly infeasible to measure the in-situ stress field and rock strength at depths where majority earthquakes occur, both surface and borehole observations have shown evidence of seismic and aseismic deformation prior to the rupture of critically stressed faults. In this study, we present both a short-term foreshock study of the 2010 Mw7.2 El-Mayor Cucapah (EMC) earthquake and a long-term seismic analysis before the 2019 ML4.0 Ohio earthquake. For both cases, we apply waveform-based methods to identify hidden smaller events and further constrain their relative locations. The detailed analysis of the EMC foreshock sequence suggests a two-scale preparatory phase leading up to the mainshock: while an active chain of foreshocks occurred immediately (within ~300s) before the mainshock suggesting cascading effect, the elongated sequence (lasting ~21 days) as well as migrating seismicity within last 8 hours also invokes a preslip mechanism. By comparison, the long-term seismicity (2013-2019) before the 2019 Ohio earthquake shows a higher but nearly constant rate (20-30 earthquake/year) when compared to the ANSS catalog. Although no pronounced accelerating seismicity was observed before the Ohio earthquake, the Coulomb stress change from water loading on the associated faulting system indicates a small positive loading effect (~0.2 kPa) when Lake Erie was in high water-level condition and the mainshock happened. Our study highlights the importance of near-field observations to capture weak seismic signals, and the complex nucleation process of faulting systems.
Presenting Author: Dongdong Yao
Student Presenter: No
Authors
Dongdong Yao Presenting Author Corresponding Author dongdony@umich.edu University of Michigan |
Yihe Huang yiheh@umich.edu University of Michigan |
Zhigang Peng zpeng@gatech.edu Georgia Institute of Techonlogy |
Liang Xue lxue07@syr.edu Syracuse University |
Yuning Fu yfu@bgsu.edu Bowling Green State University |
Raul Castro raul@cicese.mx Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE) |
Jeff Fox jeffrey.fox@dnr.ohio.gov The Ohio Seismic Network, Ohio Geological Survey |
Andrew Gronewold drewgron@umich.edu University of Michigan |
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Investigating Potential Earthquake Preparatory Phase From Short-Term and Long-Term Seismic Observations
Category
New Insights Into the Preparatory Phase of Earthquakes From Tectonic, Field and Lab Experiments