广东省及邻区活动断裂的实验研究

Experimental Research of Active Fault in Guangdong Province and Its Adjacent Region

从实验应力分析和岩石力学的角度,综合其它学科的相关理论,给出了一种有别于传统的活动断裂的新定义及其判据。其定义为:在现代构造应力场中,存在沿原断裂面破裂和扩展的断裂。其判据为:①某断裂走向与主压应力1σ方向所夹的锐角0°≤β≤50°时,其为活动断裂;②β=25°的断裂为最活动的断裂。通过对广东省及邻区活动断裂的实验研究还得到其1σ方向分布图(广东省域从东到西,1σ方向大致为305°～360°～15°)、活动断裂或活动断裂分段的走向范围以及主要活动断裂分段内潜在的最大地震。大致为:①NW走向的断裂,除西部极少数外,全部是活动断裂。各断裂分段内潜在的最大地震在MS 5.1～7.4级之间:②研究区东部的近EW向断裂、西部NE向断裂的部分分段和SN向断裂,也是活动断裂。各分段内潜在的最大地震在MS6.8～7.5级之间。

Based on the analysis of experimental stress and rock mechanics, combined with the correlative theory of the other subjects, a new definition including its criteria for active fault is given in this article, which is different from the traditional one. 1. Definition： The fault that has the qualification of fracturing and spreading along the original fault in the modem tectonic stress field. 2. Criteria： （ 1 ） It is an active fault if the acute angle β between its trend and the direction of the principal compressive stress or, is between 0° and 50° ; （2） The fault with β=25° is the most active one. Furthermore, the following results are also obtained： 1. The distribution map of σ1 direction in the region concerned. The σ1 direction is approximately between 305° and 360° from east to west in Guangdong Province. 2. The strike and range of the active fault or the sections of active fault and the maximum potential earthquake possibly occurred in the sections of main active fault in the region concerned. Namely, （1） All the faults in NW direction are the active ones except few in the west. The magnitude of the maximum potential earthquake in the sections of the faults would be between Ms5.1 and 7.4; （2） The faults in EW direction in the east, some sections of the faults in NE direction and the faults in SN direction in the west are also active ones. The magnitude of the maximum potential earthquake in the sections would be between Ms6.8 and 7.5.