Permalink : http://hdl.handle.net/2115/38162

JaLCDOI : 10.14943/gbhu.72.315

On May, 1997, Sapporo municipality installed three borehole seismometers in Sapporo city to observe microearthquakes in and in its vicinity of Sapporo. Ueyama company has also installed strong-motion and high-gain seismometers at three borehole stations in and around Sapporo since 1999. We have collected seismic record from these borehole stations as well as other highgain seismic stations operated by various organizations and have determined hypocenters of 128 microearthquakes (M=0.2-2.8) occurring beneath Sapporo urban area from May, 1997 to January, 2004. Hypocentral distribution shows clusters of earthquakes near the central part and the eastern--southeastern part of Sapporo. A focal mechanism for one earthquake estimated from P-wave first motion polarities has nearly east--west pressure axis.