HR: 1330h
AN: S52E-0170    [PDF]
TI: Signals of fluid and stress triggering in local earthquake clusters
AU: * Hainzl, S
EM: hainzl@geo.uni-potsdam.de
AF: Institute of Earth Sciences, University of Potsdam, P.O.B. 601553, Potsdam, 14415 Germany
AU: Kurz, J
EM: kurz@iwb.uni-stuttgart.de
AF: IWB, University of Stuttgart, Pfaffenwaldring 2b, Stuttgart, 70550 Germany
AB: The spatiotemporal clustering of earthquakes is of special interest because it probably contains significant information about the structural environment and the triggering mechanism of earthquakes; neither of which are well understood so far. One type of strong earthquake clustering is aftershock activity; another is the occurrence of earthquake swarms. The underlying mechanism is often assumed to be stress triggering in the former and fluid intrusions altering the resistance of faults in the latter case. However, these explanations are oversimplifications, because aftershock sequences can include swarm-like subclusters and earthquake swarms partly consist of embedded aftershock sequences. In general, stress transfers and fluid flows are expected to be coupled and it is not straightforward to reveal the dominant mechanism. The aim of this presentation is to explore which characteristics of the spatiotemporal seismicity patterns, such as rate changes or migration of activity, can be used to draw reliable conclusions. For that, we analyze seismicity patterns in response to fluid intrusion in elastic half-space models. The increase of pore pressure drives such model systems close to the critical state where stress triggering becomes important. The initial stress state is crucial for the evolving seismicity patterns. The results are compared with characteristics of aftershock sequences and earthquake swarms.
DE: 3220 Nonlinear dynamics
DE: 3250 Fractals and multifractals
DE: 7209 Earthquake dynamics and mechanics
DE: 7230 Seismicity and seismotectonics
DE: 7260 Theory and modeling
SC: Seismology [S]
MN: 2003 Fall Meeting