Session VI:
Earthquake hazard quantification in space and time : aimulation based predictions, preliminary forecasting models and forecast tests and evaluations

2nd ACES (APEC Cooperation for Earthquake Simulation) Workshop in Japan



Load-Unload Resp onse Ratio, Accelerating Moment Release, and Earthquake Prediction
Xiang-Chu Yin, Peter Mora, Ke-Yin Peng, Yu-Cang Wang, Dion Weatherley


Abstract

According to the critical point hypothesis, the Earth 's crust is not perpetually in a critical state. The occurrence of a large or great earthquake in a region appears to dissipate a sufficient proportion of the accumulated energy to remove the crust from a critical state. Subsequently, tectonic loading drives the crust back towards the critical state. During the establishment of criticality, seismic moment release accelerates in the region surrounding the epicenter of the ensuing large or great earthquake. The Accelerating Moment Release (AMR)sequences may be identified by fitting cumulative moment release prior to a large or great earthquake to a power-law time-to-failure relation. Such a t provides an intermediate-term prediction of the time of occurrence of the large or great earthquake. It has been suggested that the acceleration in seismic moment release is due to the establishment of long range correlations in the regional stress field. Such long range correlations prepare the region for a large earthquake. Once in the critical state, only a very small stress perturbation, such as that caused by Earth tides, may be sufficient to trigger earthquakes. Assuming Earth tides are sufficient to trigger earthquakes, especially moderate earthquakes, a parameter called the Load-Unload Response Ratio (LURR)may be used as a measure of the proximity to criticality.

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