Stress interaction effect on the occurrence probability of characteristic earthquakes in Central Apennines

Abstract

[1] In this study, we compute the effect of stress change due to previous historical earthquakes on the probability of occurrence of future earthquakes on neighboring faults. Following a methodology developed in the last decade, we start from the estimate of the probability of occurrence in the next 50 years for a characteristic earthquake on known seismogenic structures, based on a time-dependent renewal model. Then a physical model for the Coulomb stress change caused by previous earthquakes on these structures is applied. The influence of this stress change on the occurrence rate of characteristic earthquakes is computed, taking into account both permanent (clock advance) and temporary (rate-and-state) perturbations. We apply this method to the computation of earthquake hazard of the main seismogenic structures recognized in the Central and Southern Apennines region, for which both historical and paleoseismological data are available. This study provides the opportunity of reviewing the problems connected with the estimate of the parameters of a renewal model in case of characteristic earthquakes characterized by return times longer than the time spanned by the available catalogues and the applicability of the concept of characteristic earthquake itself. The results show that the estimated effect of earthquake interaction in this region is small compared with the uncertainties affecting the statistical model used for the basic time-dependent hazard assessment.

Orogen-scale uplift in the central Italian Apennines drives episodic behaviour of earthquake faults

“…7). Our main conclusion is that, whereas the decadal and Holocene-averaged extension rates in this area are consistent with continuum (viscous) deformation49, the millennial-scale behaviour of individual faults is more episodic, with elapsed times on some faults of several thousands of years1121. The magnitude of the maximum slip-rates (SR max ) that we infer from the 36 Cl data (up to several mm/yr; Table S4.4.2) further imply that at any given time only a small fraction of the total fault population (≤30%; or ≤2 out of 6 faults across strike; Fig.…”

Relationships between fault geometry, slip rate variability and earthquake recurrence in extensional settings

“…CV is also referred to as aperiodicity. Ellsworth et al 1999;Mucciarelli 2007;Console et al 2008;Parsons 2008), values of long-term average fault slip rate, SR mean , are assumed to be constant for a particular structure, although the quoted range is often broad because of the combination of limiting factors discussed above. Ellsworth et al 1999), yet small differences in CV can lead to order of magnitude differences in probabilistic earthquake forecasts (e.g.…”

Why the Next Large Earthquake is Likely to be a Big Surprise

“…Aimed at representing the larger seismicity of the Italian territory, this catalog relies upon a classical punch-hole declustering, with a single mainshock allowed in each cluster, and assumed to coincide with its largest event. The key issue upon which we focus our attention is the time elapsed since the last event in each individual seismogenic source being much shorter than the average return time estimated geologically (compare Console et al, 2008). What are the consequences of such an observation?…”