ESTIMATING THE CRUST PERMEABILITY FROM FLUID-INJECTION-INDUCED SEISMIC EMISSION AT THE KTB SITE

During the hydraulic-fracturing experiment in the German Continental D eep Drilling Borehole (KTB) in December 1994, microseismic activity wa s induced. Here we develop a technique for estimating permeability usi ng the spatio-temporal distribution of the fluid-injection-induced sei smic emission. The values we have obtained for the KTB experiment (0.2 5x10(-16) to 1.0x10(-16) m(2)) are in a very good agreement with the p revious hydraulic-type permeability estimates from KTB deep-observator y studies. In addition, our estimates of the hydraulic diffusivity sup port the previously calculated value for the upper crust, which is of the order of 1 m(2) s(-1). However, this estimate now relates to the d epth range 7.5-9 km.