摘要
新疆分量式钻孔应变测量已有20年的连续观测资料,期间经历新疆境内6级以上强震及邻区7级以上强震共30次,其中7级以上地震7次,8级以上地震1次。在30次地震事件中,63％的地震前钻孔应变仪记录到了异常变化。其中,天山地震带上有17次地震,有明显的地震前兆记录的13次,占76％,钻孔应变台站均分布在此带上,对地震的震前异常记录效果更好;昆仑山地震带上有9次地震,其中5次地震前记录到应变异常,占56％。阿勒泰地震带上有4次地震,均无异常记录。新疆钻孔应变仪多次重复地记录到了震前非线性应变能积累的过程,其异常的主要特征是:(1)异常类型为年变畸变、阶变、指数型、大幅度应变张-压 (压-张)型,突跳型;(2)应变异常量级≥10-6;(3)异常持续时间以短期和短临异常为主,多数在6个月以下。本文仅举10组大震观测结果,以示应变前兆的异常特征。
Component borehole strain observation has had twenty year’s data in Xinjiang area.In the period totally 30 earthquakes occurred with Ms>6.0 strong earthquakes in Xinjiang area and Ms>7.0 strong earthquakes in neighbouring area.Among these had 7 earthquakes with Ms>7.0 and 1 earthquake with Ms>8.0.During these 30 earthquake e-vents,the borehole strain instruments recorded anomalous changes before 63%earthquakes.Among 17 earthquakes in the Tianshan earthquake belt,before 13 earthquakes recorded obvious earthquake precursory changes.Among 9 earthquakes in Kunlun Mountains earthquake belt,before 5 earthquakes recorded strain anomalies.4 earthquakes in Aletai earthquake belt didn’t record anomalies.The borehole strain instruments repeatedly recorded the procedure of nonlinear strain energy accumulation before earthquakes.The main anomaly features are as follows:(1)Anomaly types include annual differences,steps,exponential changes,expanding and pressing,pulses.(2)Strain anomaly magnitudes are up to 10-6.(3)As to the durations of the short-medium-term and imminent anomalies,an overwhelming majority was less than 6 month.This paper discusses the anomaly features of strain precursor before earthquake with only 10 groups of observations.
作者
蒋靖祥
王在华
唐小勇
王新刚
Jiang Jingxiang;Wang Zaihua;Tang Xiaoyong;Wang Xingang(Seismological Bureau of Xinjiang Uygur Autonomous Region Xinjiang Urumqi 830011)
出处
《地壳构造与地壳应力文集》
2004年第A01期45-56,共12页
Bulletin of the Institute of Crustal Dynamics
