Understanding Triggered Seismicity

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

EAR-0230429 Sornette Using a class of triggered-seismicity models, we have recently (i) classified the different regimes of triggered seismicity, (ii) found that the numerous small and intermediate-sized earthquakes may have a significantly larger effect than large earthquakes on future seismicity, when taken together, (iii) showed how cascades of triggered seismicity may lead to aftershock diffusion and foreshock migration, (iv) discovered that the inverse Omori law may derive from the direct Omori law as the most probable trajectory of seismicity leading to a mainshock, and (v) explained a change of the Gutenberg-Richter law from a concave to a convex shape for foreshocks. Building on these empirical results and on our theoretical understanding of models of triggered seismicity, we will: 1) investigate several physical mechanisms underlying the local Omori's law to constrain the origins of its observed variability and to understand better the physics of triggered seismicity, 2) analyze in novel ways the data available from different catalogs, both regional (such as SCEC) and worldwide (such as ISC) which careful attention brought to their completeness and their quality; 3) perform careful and systematic explorations of reported seismic patterns and analyze them in the perspective offered by the parsimonious triggered-seismicity model; 4) develop a new statistical method for inversion of the triggering seismicity model taking into account the incompleteness of the catalogs for small earthquakes; 5) test the validity and limits of stress-transfer models that neglect cascades of triggered seismicity; and 6) develop a forecasting methodology using the triggered seismicity model with its cascade of triggered events as a strong null-hypothesis to test against other hypotheses and to develop accurate seismic hazard assessment in southern California.