论文部分内容阅读
1970年至1998年1月10日张北地震前, 沿NWW向发生2级以上地震24次, 其分布相对集中, 呈条带状。对华北台网所记上述地震的到时数据全部重新查图核对, 并补充了内蒙古台网5个台的数据以改善用于定位的台站分布, 并采用主地震定位法重新定位, 除一个地震外, 其余地震更加集中, 形成一小震条带。1998年2月中国地震局地球物理勘探中心在张北震区架设10台短周期数字化地震仪, 记录了大量微震。作者采用P波和S波到时差重新进行了震源定位, 得到184次微震的定位结果, 连同1998年1~2月张北震区3级以上地震事件定位结果一起勾画出6.2级地震的震源破裂带。由张北地震震中向SEE向延伸存在由强震构成的张家口渤海地震带。根据精确定位结果, 结合修订后主震的震源机制、宏观烈度分布和层析成像资料, 讨论了张北地震和小尺度地震带(震源破裂带)、震前的中等尺度小震条带以及大尺度的张家口渤海强震带的关系。
Before the Zhangbei earthquake from 1970 to January 10, 1998, there were 24 earthquakes of magnitude 2 or more along the NWW, with relatively concentrated distribution and stripe shape. All the data of arrival time of the above earthquake recorded by North China Network were re-checked and the data of 5 stations in Inner Mongolia were supplemented to improve the station distribution for positioning and repositioned by the main earthquake location method. Except for one Earthquakes, the rest of the earthquakes more concentrated, forming a small earthquake stripe. In February 1998, the China Earthquake Administration’s Geophysical Exploration Center set up 10 short-period digital seismographs in Zhangbei earthquake area and recorded a large number of microseisms. The authors repositioned the source using P-wave and S-wave time-differences, and obtained 184 microseismic locating results. Together with the location of the 3rd and above earthquake events in Zhangbei earthquake region in January-February 1998, the author delineated the source rupture zone of the M6.2 earthquake. From the epicenter of Zhangbei earthquake to SEE, there is a Zhangjiakou Bohai seismic belt formed by strong earthquakes. According to the precise location results, combining with the focal mechanism, the macroscopic intensity distribution and the tomographic data of the revised main shocks, the paper discusses the characteristics of the Zhangbei earthquake and the small scale seismic zone (source rupture zone), the medium-scale small earthquakes before the earthquake and the large Scale of the Zhangjiakou Bohai Sea strong earthquake zone.