Relationships Within the Precurors Before Large Earthquakes: Theory, Observations and Data Chosen

Abstract:

The Non-Critical Precursory Accelerating Seismicity Theory has been partly tested (with the method of RTL) about the same spatiotemporal window of both accelerating seismicity and quiescence, which may relate the two of the principal patterns that can precede large earthquakes. The Accelerating Moment/Strain Releasing model could be seen as the loading process between the reduced seismicity after the last huge earthquakes around the epicenter and the next rupture. So the AMR model depends on the occurrence of the quiescence. Here, we develop an approach based on the concept of stress accumulation to unify and categorize all claimed seismic precursors in a same physical framework, including the quiescence, the AMR/ASR model and the short-term activation. It shows that different precursory paths are possible before large earthquakes and can be described by a logic tree with combined criteria at a given stress state and of precursory silent slip on the fault and within the faults system. Theoretical results are then compared to the time series observed prior to the earthquake catalog from 1980 to 2012, Italy. In the initial result, the case of the 2009 Mw = 6.3 L’Aquila earthquake, Italy, the observed precursory path is coupling of quiescence and accelerating seismic release, followed by activation. What’s more, the comparison between ETAS and Stress Accumulation Model shows that precursors are statistic significant when microseismicity is considered, which holds important information on the stress loading state of the crust surrounding active faults. Based on the corrected Akaike Information Criterion (AICc), we found that quiescence and ASR signals are significant when events below a magnitude of 2.2 are included and that short-term activation is significant when events below 3.3 are included. These results provide guidelines for future research on earthquake regional risk assessment and some kind of predictability.