C-1: Prediction of Strong Earthquake Ground Motions,
Earthquake Disaster Prediction and Mitigation
This research group has four sub-theme programs.
These are as follows:
(1)Prediction of seismic activity in Hebei region;
(2)Prediction of strong earthquake ground motions in Tangshan region;
(3)Seismic risk assessment of urban region;
(4)Urban planning against strong earthquake.
We here report recent research activities and programs of sub-theme (1) and (2) in this year.
Prediction of Seismic Activity in Hebei Region
This program aims to present a method to identify anomalous seismic activities from the daily and long term seismic activities of the Hebei region. The term "earthquake activity" denotes in this program that it does not attempt to make prognoses of individual events, but forecast activity of seismicity level as a whole. In order to make a prediction of seismicity, we will set up a continuous recording system at the Institute of Geophysics, State Seismological Bureau of China(SSB), to obtain data from some selected stations.
Dr. Yang Jiansi of the Institute of Geophysics will be invited to the Disaster Prevention Research Institute (DPRI) this fall as a 1996 visiting researcher of the joint project "Evaluation of seismicity in the two tectonic regions". Her major objective of the visit is placed on quantitative evaluation of seismic activity in Beijing and its vicinity. Data records from 92 seismic stations in the said area are all telemetered as well to the Institute of Geophysics of SSB, and the hypocentral parameters are automatically and manually determined, She will conduct comparative studies of seismic activity in the continent with that in an island arc structure of central Japan, using several analyzing tools developed by us at DPRl group and others. We hope this joint work will bring us further important information for understanding the mechanism of mutual interference in seismic activity.
Prediction of Strong Ground Motions in Tangshan Region
A five-year joint research program on prediction of strong ground motions is being conducted under the joint research agreement between DPRl and IEM (the Institute of Engineering Mechanics of SSB). The cooperative activities to be conducted under the agreement are as follows: 1)Study on the effects of earthquake source, wave path and surface geology on seismic motion based on small to large ground motion prediction and its verification by using data of strong motions and earthquake motion observations and geotechnical measurements. 2)Study on strong earthquake damages. Seismic observations for strong motions are being performed in Tangshan region since 1992.As shown in Figure and Table, the seismic observation network now consists of eight stations.
Three stations of them constitute a vertical array observation system constructed by IEM in 1994. So far, 68 events were observed by our network. Earthquake hypocentres and magnitudes of 31 events of them were determined by SSB. The epicentral and station locations are shown in Figure. Earthquakes occurred along active faults running in the direction from the east to the west. The magnitude (M) of observed events ranges from 2.O to 5.1. Especially, we obtained good records at all stations of the network for the events of M4.5(September 27,1993) and M=5.1(October 6,1995).
The station of the network will be increased up to ten stations by DPRI this year. The main research theme of this year is to investigate site effects on seismic motion and seismic wave attenuation by using our seismic network data in Tangshan region.
