A three dimensional array for site effects on strong ground motion

An experimental three dimensional strong-motion array was deployed in 1994 at the Xiangtang Town in the Tangshan City where a destructive earthquake of M7.8 occurred in 1976 and completely destroyed the whole city. This array was designed to study the local soil effects on seismic ground motion. It composed of five digital strong-motion accelerographs with two on the surface rock site and other three on soil site with different depths in the boreholes.Among these five digital instruments, one was Japanese Model of CV-90lVR and the others including the down-hole system were all purchased from the Kinemetrics Ltd. of the United States. Installation of this local array was completed by the end of July 1994. Since then a number of strong-motion accelerograms were well recorded from sixty earthquakes of magnitudes ML1.5 to ML5.9 and the maximum peak ground acceleration reached up to 60cm/sec/sec.