中国大陆岩石圈最新构造变动与地震灾害

中国大陆的地震灾害十分严重，不仅分布广，而且频度高、强度大，对经济建设和社会发展构成了很大的威胁。晚第四纪岩石圈构造变动是地震发生的根本原因。一系列巨大的活动断裂将中国大陆切割成为不同级别的活动地壳块体，地块内部相对稳定，边界构造活动强烈。这些地块从晚第四纪一直持续活动至今。有历史记载以来，中国大陆的119次7级以上地震有104次发生在这些活动地块的边界带上。因而，活动地块的运动及其之间的相互作用构成了中国大陆晚第四纪构造变形的最基本特征，对中国大陆地震孕育和发生起着直接的控制作用。

LATE QUATERNARY TECTONIC DEFORMATION AND EARTHQUAKE HAZARD IN CONTINENTAL CHINA

hina is a country with high level of earthquake hazard. Statistics of globalearthquakes indicates that there have been more than 100 events with magnitude over7 occurred in China in this century , which takes up 10% of the total events (M7)in the world. Especially, about 38 Percent of global continental earthquakes occurredin continental China, which account for 52% of total global casualties caused byearthquake disasters. In China, more than 1 / 3 land surface, 1 / 2 cities, and 2 / 3megacities (population one million) are located in the areas that prone to earthquakeswith high intensity (above). As a tragic example, only from 1966 to 1978, therewere nine earthquakes() that successively struck China. These nine earthquakesoccurred in densely populated areas and caused approximately 300 000 casualties andmore than 2 billion US dollars in economic losses. Thus, seismic hazards pose amajor threat to the social and economic development of China.China is located in the southeastern part of the Eurasian plate bounded by theIndian, the Philippine Sea and the Pacific plates. The most remarkable feature is thatthe crust has been cut by huge Quaternary active faults forming active crustal blocksof different orders. These crustal blocks continue to be active from late Quaternary topresent. 104 historical earthquakes with magnitude over 7 occurred near boundaries ofdifferent crustal blocks. Thus, movements of the blocks and their interactions markthe characteristic of late Quaternary tectonic deformation.The active crust blocks are geological elements with late Quaternary tectonicactivities. Each crustal block has its own style, rate, and history of deformation.There is very little deformation in the interior of an active crustal block. Deformationcommonly takes places along their boundaries. Devastating earthquake (m7) mostlyoccurs along the major boundaries of active crustal blocks. On the basis of activetectonics and earthquake activity, continental China can be divided into blocks ofdifferent orders. different active crustal block subjects to different forces that result indifferent style of deformation and different behavior of earthquake activities.Tibetan Plateau is the most obvious active crustal block.