南北地震带强震迁移特征及其与南亚地震带的联系

THE MIGRATION CHARACTERISTICS OF STRONG EARTHQUAKES ON THE NORTH-SOUTH SEISMIC BELT AND ITS RELATION WITH THE SOUTH ASIA SEISMIC BELT

南北地震带1500年以来7级以上强震迁移显示出3种方式:由北往南大致等时距的迁移、由南往北多样式的迁移和一个时段内全带范围内的成组强震群发活动。从以往100年的强震活动分析,南北地震带的活动还与从缅甸至印尼苏门答腊的南亚地震带强震活动相关联,前者的强震往往滞后于后者几月至数年发生。因此,2004年12月26日苏门答腊岛西面海里发生8·7级大地震后南北地震带发生强震的可能性不能忽视。南北地震带上述多种强震迁移活动特征既与印度板块向NNE的碰撞、俯冲过程有关,也与青藏高原与其东北缘稳定、坚硬的鄂尔多斯和阿拉善块体的相互作用有关。

ting from Burma to Sumatra, Indonesia. Strong earthquakes along the former belt often occur several months or years after the quakes on the later belt. The above-mentioned migration characteristic of strong earthquakes is likely caused by the northward collision and subduction of the India Plate as well as coaction between the Qinghai-Tibet Plateau and the stable and hard Ordos and Alashan Massif at the northeastern margin of the Plateau. The South-to-North migration of strong earthquakes with different time intervals and different migrating rates may directly reflect the uneven, irregular pushing of the northeastern corner of the India plate, and the gradually northward transmitting and expanding of the related stress as it accumulates and strengthens. While the North-to-South migration of strong earthquakes with long time intervals and uniform rate may relate to the movement of the further deeper the strongly-deformed Qinghai-Tibet Plateau and the northern materials, or to the interaction between hard massif. Perhaps it results from the successive, north-to-south, lateral-slipping and rotational-twisting movement of the strip massifs con- stituting the Qinghai-Tibet Plateau. As for the phenomenon that strong earthquake clusters occur constantly in a certain time on the North-South Seismic Belt, it may imply that the deformation induced by India Plate indenting strongly into Eurasia continent on the eastern margin of the Qinghai-Tibet Plateau has been strengthened. And the clustering and South Asia Seismic Belt also confirms that the of strong earthquakes on North-South Seismic Belt northern collision zone and the eastern subduction zone of India Plate, as a whole, have impact on the activity of the earthquakes on the Chinese North-South Seismic Belt and Burma, Andaman till Sumatra.