Identification of seismic precursors before large earthquakes: Decelerating and accelerating seismic patterns

摘要

A useful way of understanding both seismotectonic processes and earthquake prediction research is to conceive seismic patterns as a function of space and time. The present work investigates seismic precursors before the occurrence of an earthquake. It does so by means of a methodology designed to study spatiotemporal characteristics of seismicity in a selected area. This methodology is based on two phenomena: the decelerating moment release (DMR) and the accelerating moment release (AMR), as they occur within a period ranging from several months to a few years before the oncoming event. The combination of these two seismic sequences leads to the proposed decelerating-accelerating moment release (DAMR) earthquake sequence, which appears as the last stage of loading in the earthquake cycle. This seismic activity appears as a foreshock sequence and can be supported by the stress accumulation model (SAM). The DAMR earthquake sequence constitutes a double seismic precursor identified in space and time before the occurrence of an earthquake and can be used to improve seismic hazard assessment research. In this study, the developed methodology is applied to the data of the 1989 Loma Prieta (California), the 1995 Kobe (Japan), and the 2003 Lefkada (Greece) earthquakes. The last part of this study focuses on the application of the methodology to the Ionian Sea (western Greece) and forecasts two earthquakes in that area.