琵琶湖周辺地域における強震動観測

Abstract

We are observing seismic waves from small to large earthquakes using the seismic observation network for strong ground motions deployed around Lake Biwa in Shiga Prefecture, since the March of 1992. The network consists of six stations. Two of them are on rock sites and the remaining 4 stations on soil sites. We can observe seismic motions in a wide range of particle velocity from 0.001 to 40 cm/s over a broad frequency-band from 0.017 to 45 Hz. To transfer observed data to our laboratory, we use a telemetering system by public telephone line. From comparisons of seismograms at rock sites and those at soil sites, we found a large amplification of seismic waves and a long duration of ground motions by a soft sedimentary layer.