Berlin 2005 – wissenschaftliches Programm

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AK: Akustik

AK 4: Physikalische Seismologie (Sitzungsorganisation: Sergei A. Shapiro, Berlin)

AK 4.4: Vortrag

Montag, 7. März 2005, 11:30–11:45, TU EB222

Microseismicity and seimic imaging at the KTB site - Data modeling and inversion for estimation of hydraulic properties — •Elmar Rothert and Serge A. Shapiro — Freie Universität Berlin, FR Geophysik, Malteserstr. 74-100, D-12249 Berlin

Two fluid injection experiments were conducted at the German Continental Deep Drilling site (KTB) in 1994 and 2000. Microseismicity occurred at different depth intervals and it is analyzed in terms of its spatio-temporal evolution. An approach is applied which assumes that microseismicity is triggered by a diffusive process of pore pressure relaxation. The method yields estimates of hydraulic parameters of rocks on large spatial scales. At the KTB significant variations in the evolution characteristics of the seismic activity at different depths are observed. To understand the reasons for this, the spatial relation of hypocenter locations to the distribution of seismic reflection intensities is analyzed. In order to understand the physical processes of induced microseismicity and the relation to reflection intensities, numerical simulations are permformed. The aim of the study is the analysis of the change of event numbers triggered with time, i.e., event rate and the localization of hypocenters. The synthetically triggered events and the real observation show significant similarity. The analysis confirms the hypothesis that the process of pore pressure relaxation is an important triggering factor for induced microseismicity.