Monitoring the global large earthquakes with 3D SEM Green's functions, Part III: Slip history of 2017 Mexico Mw8.2 and 2018 Alaska Mw7.9 Earthquakes
Abstract
Detailed mapping of spatial and temporal slip distributions of large earthquakes is one of the primary goals of seismology. With recent developments in global broadband seismic instrumentation and computational technology, seismologists are able to quickly constrain the earthquake slip history using realtime seismic data at teleseismic stations, and proceed to predict the local damage.However, to limit the impact of inaccurate Green's functions calculated with 1D velocity model, only the waveforms of long period (3-6 mHz) seismic waves and broadband P and S waves are used in currently routine analysis. In a companion work (Part I), we calculate and store the 3D SEM strain Green's functions at 30 GSN stations for over 210,000 source points distributing in source regions of 10 selected global earthquakes, using a state-of-art 3D earth model and reciprocity theorem. The precision of the 3D calculation is up to 67 mHz (15 s).Here, we study the slip history of two recent large earthquakes, September 8th, 2017 Mw 8.2 Chiapas Mexico earthquake and January 23th, 2018 Mw 7.9 Gulf of Alaska earthquake using the computed 3D earth response. In contrast with previous endeavors that use 3D Green's functions in source inversion, we intend to take full advantage of 3D earth response without sacrificing the benefits of traditional approaches. First, to honor the fact that the current 3D Green's functions still contain errors in travel time, we truncate the data and synthetic seismograms into seismic phases before waveform comparison. The phase dependent bandwidth information obtained through the evaluation works using both aftershocks (Part I) and available slip models (Part II) will be carefully included. Second, the traditional high-frequency first motion approximation (Langston et. Al., 1975), which has been proved to be able to model the broadband teleseismic P and S waves well, will be kept to avoid the sacrification in bandwidth when using 3D strain Green's functions.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.S31F0579H
- Keywords:
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- 7203 Body waves;
- SEISMOLOGYDE: 7215 Earthquake source observations;
- SEISMOLOGYDE: 7219 Seismic monitoring and test-ban treaty verification;
- SEISMOLOGYDE: 7230 Seismicity and tectonics;
- SEISMOLOGY