Is the dependence on the temperature of the friction important in stress triggering phenomena? The case of the 2000 Iceland seismic sequence

摘要

We perform numerical experiments by using a mass–spring fault model subject to an externalcoseismic stress perturbation due to a remote seismic event happening on another fault, the causative fault. Inparticular, the aim of this study is to investigate the instantaneous fault interaction and possible triggeringthat happens when a fault perturbed by a stress change fails before the so–called unperturbed instability. As arealistic example we focus our attention on the instantaneous dynamic triggering phenomena occurred duringthe 17 June 2000 south Iceland seismic sequence in the South Iceland Seismic Zone (SISZ, ReykjanesPeninsula). The main event (Ms 6.6) was followed by three large events within a few tens of seconds (8, 26and 30 s, respectively) located in a neighborhood of several tens of km. Among them the 26 s event was thebest constrained (Bizzarri and Belardinelli, 2008).In the present study, conditions to simulate the instantaneous dynamic triggering connected to theformer three events, have been investigated using the simple 1–D spring–slider analogue model representinga fault governed by the rate– and state–dependent friction laws. In previous studies suitable constitutiveparameters of the modeled fault which allow the instantaneous triggering of the three events, have beenfound (Antonioli et al., 2006) and, furthermore, it was also shown how the dynamics of the 26 s eventstrongly depends on the assumed constitutive law and stress conditions (Bizzarri and Belardinelli, 2008) byconsidering the Dieterich–Ruina (DR henceforth) and the Ruina–Dieterich (RD henceforth) governing laws.In this context take place the present study original contribution that is to better understand if the conditionsof instantaneous dynamic triggering (focusing on the case of the 26 s triggered event) provide any significantdifferences if modeled with a different rate– and state–dependent governing equation, the Chester and Higgslaw (CH henceforth; see Chester and Higgs, 1992; Bizzarri, 2010b; Bizzarri, 2010c) which accounts for the thermal effect for frictional heating which may occur during seismic sliding.