岷县漳县Ms6.6地震前武都、天水钻孔应变异常变化分析

Relation of the Minxian-Zhangxian Ms6.6 Earthquake to Abnormal Changes of Borehole Strain in Wudu and Tianshui

摘要:

2013年7月22日岷县漳县M_s6.6地震前2~3月内,武都、天水应变资料出现了不同程度的异常变化,其中两台的NW道异常都非常显著,与2003年、2004年2次岷县地震前武都应变出现的异常很相似,都有β₁、β₂、γ₁三阶段前兆异常特征。

Abstract:

Wudu and Tianshui strain stations have monitored the stress and strain near fractures and tectonic belts in southeastern Gansu since a few decades ago. As an effective observation method of earthquake precursors, it is of extremely vital significance and before many earthquakes it responded really well. The borehole strain gauge of pressure vessel style used in Wudu and Tianshui is the latest generation of strain gauge. In two or three months before the Minxian-Zhangxian M_s6.6 earthquake, the strain data in Wudu and Tianshui had shown varying degrees of abnormal changes. The NW orientation of two strain gauges appeared extremely obvious a-nomaly, which was similar to that in Wudu before two earthquakes which occurred in Min county in 20003 and 2004. They showed the same characteristics of precursory anomalies in three stages of,β₁,β₂ and γ₁.