Seismic Wavefield Imaging Based on the Replica Exchange Monte Carlo Method: Application to MeSO-net Data, Tokyo Metropolitan Area, Japan
Abstract
Earthquakes sometimes cause serious disasters not only directly by ground motion itself but also secondarily by infrastructure damage, particularly in densely populated urban areas. To reduce these secondary disasters, it is important to rapidly evaluate seismic hazards by analyzing the seismic responses of individual structures due to the input ground motions. Such input motions are estimated utilizing an array of seismometers that are distributed more sparsely than the structures.We propose a methodology that integrates physics-based and data-driven approaches in order to obtain the seismic wavefield to be input into seismic response analysis. This study adopts the replica exchange Monte Carlo (REMC) method, which is one of the Markov chain Monte Carlo (MCMC) methods, for the estimation of the seismic wavefield together with one-dimensional local subsurface structure and source information. Numerical tests show that the REMC method is able to search the parameters related to the source and the local subsurface structure in broader parameter space than the Metropolis method, which is an ordinary MCMC method. The REMC method well reproduces the seismic wavefield consistent with the true one. In contrast, the ordinary kriging, which is a classical data-driven interpolation method for spatial data, is hardly able to reproduce the true wavefield even at low frequencies. This indicates that it is essential to take both physics-based and data-driven approaches into consideration for seismic wavefield imaging.Then the REMC method is applied to the waveforms observed by MeSO-net (Metropolitan Seismic Observation network), in which 296 accelerometers have been densely distributed with several kilometer intervals in the Tokyo metropolitan area, Japan. Our initial result indicates that seismic wavefield in the period at least longer than 5 s is well reproduced, which will contribute to evaluate the seismic responses of high-rise buildings.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.S33D2862K
- Keywords:
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- 7212 Earthquake ground motions and engineering seismology;
- SEISMOLOGY