Study on relationship between features of strain anomaly obtained by borehole strain meter at Wushi station in Xinjiang and strong earthquake: Taking Jiashi M s=6.8 earthquake as an example

The borehole strain meter at Wushi station recorded obvious anomaly before Jiashi M _s=6.8 earthquake occurred on February 24, 2003. Its features are as follows. (1) Anomaly types are complete. The trend anomaly, short-term anomaly, short-imminent anomaly and exponential anomaly appeared 19 months, 56 days, 4 days, and more than 1 month before the event, respectively; (2) Anomaly is large in magnitude. The maximal magnitude of strain anomaly is 1.7×10⁻⁵, which is rare in the past 20-year observation records at Wushi station; (3) Strain rate fluctuates sharply with obvious alternation of tension and compression. According to the magnitude of strain anomaly, time of exponential anomaly appearance and regional features of recorded anomaly, we could predict the magnitude, occurrence time and potential region to a certain degree.     

Study on relationship between features of strain anomaly obtained by borehole strain meter at Wushi station in Xinjiang and strong earthquake: Taking Jiashi <Emphasis Type="Italic">M</Emphasis><Subscript>s</Subscript>=6.8 earthquake as an example

The borehole strain meter at Wushi station recorded obvious anomaly before Jiashi M _s=6.8 earthquake occurred on February 24, 2003. Its features are as follows. (1) Anomaly types are complete. The trend anomaly, short-term anomaly, short-imminent anomaly and exponential anomaly appeared 19 months, 56 days, 4 days, and more than 1 month before the event, respectively; (2) Anomaly is large in magnitude. The maximal magnitude of strain anomaly is 1.7×10^?5, which is rare in the past 20-year observation records at Wushi station; (3) Strain rate fluctuates sharply with obvious alternation of tension and compression. According to the magnitude of strain anomaly, time of exponential anomaly appearance and regional features of recorded anomaly, we could predict the magnitude, occurrence time and potential region to a certain degree.