Earthquake multiplets and dynamic triggering in the western Corinth rift
IPGP - Îlot Cuvier
Séminaires de Sismologie
The Corinth rift (Greece) is one of the most active tectonic structures of the euro-mediterranean area, with six earthquakes of magnitude M>6 during the last century. The seismic activity follows a swarm organization with alternation of intensive crisis and more quiescent periods. A large number of multiplets, which are a set of earthquakes with a similar waveform, are recorded in the western part of the rift. Multiplets are often assimilated as repeated ruptures of small asperities due to transient forcing such as silent creep or diffusion of a pore pressure front. Here, I will present different analyses on microseismic multiplets occurring in the western Corinth rift from 2000 to 2014 to retrieve their spatio-temporal characteristics and their coupling with seismic-aseismic processes. Firstly, I will focus on slow transient forcings with evidence of (1) fluid pore pressure migrations during the 2003-2004 seismic crisis, (2) creep through a repeater-like multiplet initiating the 2003-2004 swarm and the specific clustering of a multiplet located at the border of the fault plane of the 1995 Aigion seismic rupture. I will then compare multiplets with a persistent activity through several years, suggesting some forcing by creep, and short-lived (few days) multiplets, possibly related to fluid pressure instabilities. Secondly, I will analyze the dynamic triggering by two moderate regional earthquakes: the 8 June 2008 Mw 6.4 and the 22 January 2010 Mw 5.2. These events produced a global increase of the local microseismicity, and we attempt to characterize the differences in sensitivity of the various local clusters to the dynamic triggering.