川东南地区地震视应力时空分布特征  

Spatial and temporal distribution of seismic apparent stress in the southeast of Sichuan Province

作　　者：宫悦[1] 龙锋[1] 乔慧珍[1] 赵敏[1] 王宇玺[1] 

机构地区：[1]四川省地震局,中国成都610041

出　　处：《地震地磁观测与研究》2015年第2期6-12,共7页Seismological and Geomagnetic Observation and Research

基　　金：地震科技专项项目

摘　　要：利用四川数字地震台网记录资料,计算2008年汶川地震后,川东南地区ML 3.0以上地震的震源动力学参数特征,分别得到视应力、应力降与震级之间、震级和地震矩之间,以及地震矩和视应力之间的定标关系。通过扣除震级影响,计算归准化视应力值的时空变化特征。得到结果如下:1从时间分布图来看,研究区4级以上地震频发时段刚好对应视应力涨落较明显时段,而该时段当地工业采矿注水活动强烈,故该区域视应力水平或许反映了工业活动对区域应力场的影响;2从空间分布图来看,自贡隆昌一带震级偏大,视应力反而偏小的现象可能与该区域应力释放不充分、构造应力水平偏低有关,未来要关注该区域发生中强地震的可能。This paper obtains the following scaling relations after calculating the seismic source dynamically parametric features of earthquakes aboveML3.0, which were observed in southeast Sichuan after Wenchuan earthquake by using the digital seismic data by Sichuan Seismic Network. Those scaling relations are：①Apparent stress ＆amp;earthquake magnitude.②Stress dropping ＆amp; earthquake magnitude,③Earthquake magnitude ＆amp; seismic moment. ④Seismic moment ＆amp; apparent stress. Based on the above relations, it further calculates features of spatio-temporal changes whose apparent stress is normalized, and thus reaches the following conclusions.①In the viewpoint of temporal distribution, earthequake-prone periods of researched zone of ML≥4.0 earthquakes happen to correspond to periods whose fluctuation of apparent stress is evident. Local intense mining water injection happened to be in the same time. Thus, the apparent stress level of researched zone might refl ect the industrial activity impact on the regional stress fi eld.②In the viewpoint of the spatial distribution, the reason why Zigong-Longchang area has larger magnitude whereas its apparent stress is relatively small might attribute to its insuffi cient release of apparent stress and low tectonic stress level. Special attention should be paid to the probable strong earthquake in this area.

关 键 词：视应力 应力降 震级 地震矩 时空分布 

分 类 号：P315[天文地球—地震学]