华北地区中强地震时间间隔特征与目前大形势分析

摘要

针对目前华北地区5、6级地震持续平静的复杂形势,分析了华北地区1484年以来M≥5、M≥6级地震的时间间隔特征,结果表明:①1731～1814年地震平静期的5、6级地震的平均时间间隔明显长于1484～1730年及1815年以来2个地震活动期的平均时间间隔,说明华北地区地震起伏交替轮回的韵律性是客观的;②华北地区2个地震活动期中相邻活动幕的幕间M≥5地震(含平静幕里发生的地震)平均时间间隔(86月)与1731～1814年平静期内单次M≥5级地震平均时间间隔(90月)一致,90月可做为华北地区5级地震异常平静的标志性时间；③类比500多年华北地区5、6级地震的时间间隔特征认为,当前华北地区正处于2000年以来的平静幕后期,该平静幕已持续169月,已经随时有可能发生5、6级地震,开始进入新一轮的地震活动幕.%In this pape,according to the complicated current situations of continuous quiescence of 5 and 6 magnitude earthquakes in North China,interval characteristics of earthquakes with M≥ 5 and M≥6 in North China since 1484 were analyzed.Analytical results showed that:① The average interval of 5 or 6 magnitude earthquakes during the seismically-quiet period between 1731 and 1814 was significantly longer than that between 1484 and 1730 as well as since 1815,which indicates that there is an objective alternating rhythmicity in earthquakes of North China; ②The average interval (86 months) of earthquakes with M≥5 (including those in seismically-quiet curtains) between adjacent seismically-active curtains in the two seismically-active periods in North China was consistent with that (90 months) during the seismiccally-quiet period between 1731 and 1814,and hence 90 months can be regarded as the characteristic duration of abnormal seismic quiescence of earthquakes with M ≥5 in North China; ③ The analogy of interval characteristics of 5 or 6 magnitude earthquakes in North China in recent 500 years shows that the current North China is undergoing the latter seismically-quiet curtain since the year 2000,and because the seismically-quiet curtain has lasted for 169 months,there is a possibility of 5 or 6 magnitude earthquakes at any time,followed by a new round of seismically-active curtain.