A method to model broadband source process of interplate earthquakes for ground motion prediction is examined through comparing predicted ground motion with observation for the 2003 Tokachi-oki, Japan, earthquake. Recent studies (e.g., Nagai et al. (2001)) show that asperities (patches with relatively large slip on a source fault) of interplate earthquakes are fixed over recurrent earthquakes. Following this idea, I assume that the long- wavelength feature of the slip distribution , i.e., asperity distribution, of a future earthquake is to be the same as what was derived by source inversion analysis. The shorter-wavelength feature, which is not constrained by the source inversion is added taking consideration of stochastic characteristics of earthquake source. Multi-scale heterogeneity is introduced to both the slip distribution and the rupture velocity distribution of the inverted source model by increasing or decreasing the values in randomly-distributed, various-size patches. The amount of the increase/decrease of the slip is set proportional to the radius of the patch and that for the rupture velocity is set to constant which gives adequate variation seen in many source inversion results. Finally, the amplitude of slip spectrum is adjusted to decay as k-1.75, which was derived by Mai and Beroza (2002) that conducted stochastic analysis of earthquake slip complexity using many published source models. A slip velocity time function approximated from dynamic rupture simulation (Nakamura and Miyatake, 2000) is assumed. The 2003, Tokachi-oki, Japan, earthquake occurred along the Kuril trench provided plenty of ground motion waveform data and the source process models are estimated using the waveform data. I construct a broadband source process model from an inverted source model by Aoi et al. (2006) and compare synthetics with the observation at sites less subjected to subsurface structure. The adequacy of deciding microscopic source parameters responsible to generation of high frequency components is examined.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- 7212 Earthquake ground motions and engineering seismology;
- 7215 Earthquake source observations (1240)