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

Abstract

We perform numerical experiments by using a mass–spring fault model subject to an external coseismic stress perturbation due to a remote seismic event happening on another fault, the causative fault. In particular, the aim of this study is to investigate the instantaneous fault interaction and possible triggering that happens when a fault perturbed by a stress change fails before the so–called unperturbed instability. As a realistic example we focus our attention on the instantaneous dynamic triggering phenomena occurred during the 17 June 2000 south Iceland seismic sequence in the South Iceland Seismic Zone (SISZ, Reykjanes Peninsula). The main event (Ms 6.6) was followed by three large events within a few tens of seconds (8, 26 and 30 s, respectively) located in a neighborhood of several tens of km. Among them the 26 s event was the best constrained (Bizzarri and Belardinelli, 2008). In the present study, conditions to simulate the instantaneous dynamic triggering connected to the former three events, have been investigated using the simple 1–D spring–slider analogue model representing a fault governed by the rate– and state–dependent friction laws. In previous studies suitable constitutive parameters of the modeled fault which allow the instantaneous triggering of the three events, have been found (Antonioli et al., 2006) and, furthermore, it was also shown how the dynamics of the 26 s event strongly depends on the assumed constitutive law and stress conditions (Bizzarri and Belardinelli, 2008) by considering 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 conditions of instantaneous dynamic triggering (focusing on the case of the 26 s triggered event) provide any significant differences if modeled with a different rate– and state–dependent governing equation, the Chester and Higgs law (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.