Are large earthquakes preferentially triggered by other large events?

Abstract

Fundamentally related to the ultraviolet (UV) divergence problem in physics, conventional wisdom in statistical seismology is that the smallest earthquakes, which are numerous and often go undetected, dominate the triggering of major earthquakes, making accurate forecasting of the latter difficult if not inherently impossible. Using the general class of epidemic type aftershock sequence (ETAS) models and rigorous pseudo-prospective experiments, we show that ETAS models featuring a specific magnitude correlation between triggered and triggering earthquakes and a magnitude-dependent Omori kernel significantly outperform simpler ETAS models, in which these features are absent. Using the best forecasting model, we then show that large events preferentially trigger large earthquakes. These findings have far-reaching implications for short-term and medium-term seismic risk assessment and the development of a deeper theory without UV cut-off that is locally self-similar.Plain Language Summary Conventional wisdom in statistical seismology is that the smallest earthquakes, which are numerous and often go undetected, dominate the triggering of major earthquakes, making accurate forecasting of the latter difficult if not inherently impossible. Here, we demonstrate that a significant fraction of large events are triggered by previous large events. Being large, these triggering events are completely reported in available earthquake catalogs. Thus, forecasting large events preceded by a set of seismic precursors would not be spoiled by the noise created by the myriad of small events whose recording is incomplete or whose parameters are highly uncertain.NANDAN ET AL.

On the Use of High‐Resolution and Deep‐Learning Seismic Catalogs for Short‐Term Earthquake Forecasts: Potential Benefits and Current Limitations

“…The latter is a significant factor for models of earthquake interactions to track the fine‐scale evolution of the stress state that controls the local conditions for earthquake nucleation (Hanagan et al., 2022; Hanks, 1992; Helmstetter, 2003; Helmstetter et al., 2005; Marsan, 2005; Meier et al., 2014). Although counterevidence has been occasionally reported (e.g., Nandan et al., 2022), there is now a growing body of evidence supporting the notion that triggering contributions and local faulting patterns of small‐magnitude events help forecast larger earthquakes not only in stress‐based forecasts (Cattania et al., 2018; Mancini et al., 2019, 2020; Parsons et al., 2012; Segou & Parsons, 2014) but also for statistical models across long‐term time‐independent experiments (Helmstetter & Werner, 2012; Helmstetter et al., 2007; Werner et al., 2010, 2011) and short‐term time‐dependent tests (Helmstetter et al., 2006; Werner et al., 2011). Fully prospective evaluations by the Collaboratory for the Study of Earthquake Predictability (CSEP; Michael & Werner, 2018; Schorlemmer et al., 2018) corroborate these findings (Bayona et al., 2022; Zechar et al., 2013).…”