MICROSEISMIC INVESTIGATION OF THE KIJIYAMA-SHITANOTAI GEOTHERMAL

Abstract

In 2012 and 2017, temporary seismic networks were installed
at a Kijiyama-Shitanotai geothermal field, Akita prefecture,
Japan. Microseismic data was gathered using these networks
for three months in each case. The networks were located in
different areas of the geothermal system. The data was
analyzed to identified of 499 local micro-earthquakes in 2017
and 475 in 2012 (a total of 974). From this data a velocity
model was derived, and the earthquakes located. The shear
waves recorded were analyzed for shear wave splitting (SWS).
The SWS splitting results were used to derive a threedimensional
crack density model and polarization direction.
The SWS result indicates a high in crack density and NE
striking fractures in the north of the seismic network and NW
striking in the south.