The effect of seismic swarms on short-term seismic hazard and Gutenberg-Richter b-value temporal variation. Examples from Central Italy seismic activity durign October-November 2023.

Abstract

Seismic hazard can be quantified by using probabilities. Modern seismic forecasting models, such as Operational Earthquake Forecasting (OEF) systems, allow us to quantify short-term variations of such probabilities. These probabilities change indeed with time and space, in particular after strong seismic events. However, the short-term seismic hazard could also change during seismic swarms, e.g. sequences with several small/medium size events. The goal of this work is to quantify these changes by both using the Italian OEF system, and estimating the variations of the b-value parameter in Gutenberg-Richter frequency-magnitude distribution. We focus our attention on three seismic swarms that occurred in Central Italy during October-November 2023. Our results indicate that the short-term variations of seismic hazard are limited, less than an order of magnitude. The b-value variations are also not significant. Our conclusion is then that, with the currently available models and catalogs, occurrence of seismic swarms does not significantly affect the short-term seismic hazard.