东北中强震的孕震机理

SEISMOGENESIS OF INTERMEDIATE STRONG EARTHQUAKES IN NORTHEAST CHINA

东北地处蒙古板块的东部.自渤海湾,经海城至绥化、萝北一线,是蒙古板块内部的次一级块体的边界,因而形成完整的地震构造线.蒙古板块受印度板块、欧亚板块、中国东部板块、日本海沟俯冲带和萨哈林地块的挤压,同时受贝加尔湖地壳扩张区的地幔流的东南向的张性拖曳作用.除了在板块边界地区不断孕育强震之外,在蒙古板块的内部,还形成了贝加尔湖至布特哈旗和从海城经平壤至日本九州岛的两条明显的北西向地震条带.它们形成了东北地区中强震的主要格局.作者认为太平洋板块沿日本海沟的俯冲作用,是东北深震孕育的直接原因,但它不是东北浅震形成的主要原因.日本海沟的大震,对东北中强震有明显的调制作用.

Northeast china is in the east of Mongolian plate. The belt from Haicheng through shuihua to Luobei i.s the boundary of second block in Mongolian plate. Thus, seismotectonic line is generated. Mongolian plate is been compressing by Indian plate. Eurasian plate, East China plate, subduction zone of Japan trench and sakhalin plate. In the meantime, mantle convection of Baikal rift zone in Southeast direction. Strong earthquakes continuously occurred along the plate boundaries And the belts from Baikal lake to Butehaqi and from Haicheng through penyang to kyushu of Japan are apparently two main seismic zones in the direction of northeast. We assume that subduction process of Japan trench is cause of deep seated earthquakes but is not important cause to give rise to shallow shockes in Northeast China. The big earthquakes of Japan trench play apparently an role to modulate intermediate strong earthquakes of Northeast China.