Investigation of fluid-controlled seismicity in a swarmquake area

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The important role of fluids in the rupture and/or initiation process of any kind of earthquakes (induced, tectonic, deep, shallow, large, small) is undisputed. Yet, the particular mechanisms through which fluids and associated parameters influence the stress regime and thus the seismicity of a particular area are not well understood. Fluids are thought to play a dominant role of intraplate earthquake swarms where the deformation rate is small compared to tectonically active regions. Here, we propose to carry out an extensive study of the spatio-temporal behavior of earthquakes, fluid-related parameters (e.g. ground water levels) and atmospheric observables (e.g. rainfall, atmospheric pressure) in the swarmquake area of Bad Reichenhall, in the southeast of Germany. In addition to a data set with several hundred small earthquakes recorded in 1995, a permanent seismic network installed in the study area in the year 2000 allowed the collection of data from several earthquake swarms, the last of which followed shortly after the heavy rainfall in August 2002 (causing the devastating floods in Germany) with more than 500 seismic events. The goal of this study is to attempt to give a (quantitative) answer whether (and how) rainfall, snowmelt, ground-water level, pressure (gradients), overburden pressure, are causally related to the observed seismicity patterns in space and time. The major benefits of the proposed study area are (1) the confined volume in which the earthquakes take place; (2) the frequently occuring earthquake swarms; and (3) a permanently monitoring, modern near-real time network in the study area independently supported by the Bavarian state.