Pore-pressure diffusion: A possible triggering mechanism for the earthquake swarms 2000 in Vogtland/NW-Bohemia, central Europe

Abstract

Vogtland/NW-Bohemia (VB) at the German/Czech border region is characterized by recurring intraplate earthquake swarms, Quaternary volcanism, intersecting fault systems, and an established connection between ascending magmatic fluids and seismicity. As the triggering mechanism of seismicity in VB is still unknown, this study aims to contribute by investigating the possible role of fluids in VB, based on poromechanics. We assume that ascending fluids, of magmatic origin, trigger earthquakes by the mechanism of pore-pressure diffusion (i.e., relaxation). Two physical fields, the hydraulic diffusivity and the criticality (i.e., critical pore-pressure value leading to failure), both heterogeneously distributed in rocks, mainly control this triggering process. The results of the analysis of the year 2000 earthquake swarm data support this concept. It is further strengthened by a numerical model, with correlated diffusivity and criticality fields, which successfully simulates the general spatio-temporal seismicity pattern of the earthquake swarms 2000. © 2003 by the American Geophysical Union.