关键词: 构造异常, 参数扫描, 群体特征

Abstract: 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.

Key words: Tectonic anomaly, Parameter scanning, Group characteristics