京津冀地区历史地震事件时空特征研究*

受环太平洋地震带影响,华北平原地区地震频发,尤其是处于中国首都经济圈的京津冀地区的地震事件备受关注。通过对历史文献资料及地震台网记录中的地震事件统计、分析,重建该地区地震事件历史并获取其潜在的空间分布特征及时间规律,对未来地震事件的早期预警具有重要参考意义。分析结果表明,公元前231年至公元2018年期间京津冀地区发生的1044起地震事件中,以有感地震和中强地震为主,小地震、强烈地震以及大地震发生频次较低。地震记录完整性分析结果表明,除小地震外,其他等级地震记录自公元1400年以来基本完整。在空间分布上,京津冀地区历史地震呈“T”字形分布,沿1条北西—南东走向地震带和1条北东—南西走向地震带分布。在时间上,京津冀地区地震事件呈现出阶段性的变化,在公元1480—1680年间以及1950年以来2个时间段内较为活跃,发生频率较高,频谱分析结果进一步表明地震记录存在45年的复发周期。在月际尺度上,地震事件同样存在季节性差异且多发于夏秋季节,同时地震密集区域在年内呈现出自西向东迁移的现象。最后,根据历史地震事件发生的时间规律,在未来一段时间内京津冀地区仍将处于地震活跃期,存在发生强震的风险。

Spatial-temporal distribution of historical earthquake events in Beijing-Tianjin-Hebei area

The North China Plain is located in the Circum-Pacific Seismic Belt where earthquakes occur frequently. The Beijing-Tianjin-Hebei area,which is the capital economic circle,has attracted much attentions. It is of great significance for the reconstruction of earthquake history to obtain the spatial and temporal distribution characteristics in this region,which may provide important reference for the early warning of earthquake events in the future. Therefore,earthquake events recorded in historical documents and seismic stations were collected and analyzed in this study. The results show that 1044 earthquake events were recorded in Beijing-Tianjin-Hebei area between 231 BC and 2018 AD. The felt earthquakes and moderate earthquakes were the main types,while small earthquakes,strong earthquakes and major earthquakes showed rather low frequencies. The seismic record integrity analysis confirms that the earthquake(M>3)records were basically complete since 1400 AD,which could be used for statistical analyses. The historical earthquakes in Beijing-Tianjin-Hebei area represent a T-shape spatial distribution,consisting of a northwest to southeast seismic zone and a northeast to southwest seismic zone. The historical earthquake records presented periodic variations,showing much higher frequencies during the periods of ca. 1480-1680 AD and after 1950 AD. The spectral analysis on the earthquake frequency sequence yields a recurrence period of 45 years,which represents a kind of recurrence time for the high frequent earthquake years. In addition,the earthquake events expressed monthly variations as well,revealing higher frequencies during summer and autumn months,along with a seasonal migration of high frequency region from west to east in the study area. Finally,according to the temporal distribution of the earthquake events,the Beijing-Tianjin-Hebei area will possibly experience a period of high potential of destructive earthquakes in the near future.