摘要
应用山东省和江苏省地震局"九五"地质研究成果,在华东地区共选择49条断裂和7个构造块体作为地震活动性研究的构造基础,选用频度、ΔT T、小震调制比3个参数,对构造两侧各20km宽度范围的地震资料进行参数时间扫描。通过普查,得到的构造优势映震距离为300km;得到了10个敏感构造及其映震特点。通过对华东地区13个中强地震震例的构造异常的综合分析,得到如下认识:①震前存在场的群体异常特征,表明华东中强地震"前兆"是在构造应力作用下表现出的、区域性的整体过程;②异常的构造常常分布在震中周围;③地震常常发生在平静异常的构造附近;④高频度异常常常发生在震中外围,并常具有步进性;⑤震中周围的构造在震前2～3年开始先后不断出现高频和平静异常,平静后出现多处小震调制比高值是孕震中期向短期过渡的时间转折标志。
Making use of the Ninth Five-year-project geological research result produced by the Seismological Bureau of Shandong Province and the Seismological Bureau of Jiangsu Province, we selected 49 faults and 7 tectonic blocks in East China region as the tectonic basis for seismicity research, and selected the seismic frequency, the ΔT-T, and the small earthquakes modulation ratio as the seismic scanning parameters to do the time-domain scanning to the seismic data of the earthquakes that occurred on each side within 20 km in width to the fault. Through the study, we obtained the predominant earthquake reflecting distance that is 300 km, and obtained 10 sensitive tectonic settings and their earthquake reflecting characteristics. By synthetic analysis of the tectonic anomaly for 13 moderate or strong earthquakes occurred in East China region, we obtained the following understandings: ① There are field group anomalies before an earthquake occurrance. The moderate or strong earthquake precursors reflect the regional tectonic movement process under tectonic stress. ② The abnormal tectonic settings are usually distributed around the epicenter of the earthquakes. ③ Earthquakes often occur in the vicinity of the quietness abnormal tectonic settings. ④ High frequency anomalies often appear away from the epicenter and gradually close to the epicenter. ⑤ In the tectonic settings around the epicenter of an earthquake, high frequency anomaly and quietness anomaly begin to appear in succession 2 to 3 years before the earthquake. After the quietness anomaly, high values of small earthquake modulation ratio may appear in several areas. This is the turning point sign of the transition from mid-term to short-term earthquake preparation.
出处
《地震》
CSCD
北大核心
2004年第3期61-68,共8页
Earthquake
基金
"十五"国家科技攻关项目(01 04 01)
