AN INHOMOGENEOUS DISTRIBUTION MODEL OF STRONG EARTHQUAKES ALONG STRIKE-SLIP ACTIVE FAULT SEGMENTS ON THE CHINESE CONTINENT AND ITS IMPLICATION IN ENGINEERING SEISMOLOGY

Through the statistical analysis of earthquake distribution along 5 1 strike-slip active fault segments on the Chinese continent, we found that strong earthquake distribution along the seismogenic fault segments is inhomogeneous and the distribution probability density P(K)can be stated as P(k)=1.1206e-3947ă2 in which K=S/(L/2), CS refers to the distance from earthquake epicenter to the center of a fault segment, L is the length of the fault segment. The above model can be utilized to modify the probability density of earthquake occurrence of the maximum magnitude interval in a potential earthquake source. Nevertheless, it is only suitable for those potential earthquake sources delineated along a single seismogenic fault.

This inhomogeneons model has certain effects on seismic risk assessment, especially for those potential earthquake sources with higher earthquake rates of the maximum magnitude interva1. In general, higher reoccurrence rate of the maximaul magnitude interval and lower exceeding probability level may bring larger difference of the results in seismic risk analysis by adopting the inhomogeneons model, the PGA values increase inner the potential earthquake source, but reduce near the vicinity and out of the potential earthquake source.

Taking the Tangyin potential earthquake source as an example, with exceeding probability of 10% and 2% in 50 years, the difference of the PGA values between inhomogeneous model and homogenous models can reach 12%. As a new technique in the field of seismotectonics developed in the late 1980's, fault segmentation has so far been a hot spot attracting numerous researchers. Most large faults do not produce ruptures along their entire length during individual rupture events, but instead, consist of segments that may rupture independently of each other, each with its own rupture history(Schwartz and Coppersmith, 1984–1986). Since the last 1990's, great progress has been achieved in study of fault segment identification, segment persistence, segment interaction, as well as the seismic risk assessment of active segments.

Active fault segmentation has become a basic method in predicating fault rupture location and related length along a fault because the quantitative analysis in seismic risk assessment on an active fault is performed on each segment unit.