2001～2007年四川及周边地区地震时空分布特征

Temporal and Spatial Distribution Characteristics of Earthquake in Sichuan and Its Surrounding Areas from 2001～2007

依据中国地震台网实测资料,对四川省及周边地区2001年1月～2007年12月期间4级以上地震进行统计,共计155次,每年平均约22次,同时鉴于汶川大地震余震尚未平息,目前还处于活动期,因此对其单独进行探讨。运用Excel和地理信息系统软件对地震活动的时间序列和空间分布特征进行分析,尝试性地探索其中的规律。结果表明,地震活动在时间分布上存在着明显的季节差异(夏、秋两季的地震活动频率明显高于春、冬两季)和年际变化(2008年为地震活跃期),在空间分布上地震活动与地质活动构造关系密切,地震主要发生在断裂、断陷带,特别在地块交界处发生率最高。

According to the records of seismic network of China, there were 155 earthquakes above 4 magnitudes in Sichuan and its surround- ing areas from January of 2001 to December of 2007. There were 22 earthquakes in each year on average. At the same time, in view of Wenchuan earthquake aftershocks was noto yet over and still in the active stage, they were explored especially. The spatial-temporal characteristics of those earthquakes were analyzed by using software of Excel and GIS. The research results indicated that the distribution of seismic activity had obvious difference in different seasons （ the frequency of the seismic activity in summer and autumn was significantly higher than that in spring and winter） and inter-annual changes （2008 was the seismically active period）. The seismic activity was closely related with the geological tectonic activity on the spatial distribution. Earthquakes mainly occurred in the fracture, down-faulted zone, particularly in the plot at the junction of the highest incidences.