三江地区不同场源重力场特征及其与构造、地震的关系

利用重力场实测资料及最新的高分辨率超高阶重力位模型 IGG97LB(72 0阶 )计算了三江地区不同场源的重力场。在分析研究了不同场源重力场特征之后 ,结合地震层析成像资料 ,得出了初步结论 :(1)三江地区的康滇菱形块体内部的物质是由青藏高原下面物质向南东方向延伸来的 ,可见康滇菱形块体与青藏高原的关系密切 ;(2 )康滇菱形块体的低速度层厚度大于周边地区 ;(3)从三江地区重力场特征及历史上地震发生的情况看 ,地震容易发生在重力异常等值线拐弯处 ,特别是复杂的等值线拐弯处 ,更是地震的多发区。

CHARACTERS OF GRAVITY FIELDS CONTRIBUTED FROM DIFFERENT SOURCES AND ITS RELATIONS TO TECTONIC AND EARTHQUAKE IN SANJIANG REGION

The gravity fields contributed from different sources of the earth interior in Sanjiang region are computed by using the observed data and the high resolution geopotential model IGG97LB (to degree and order 720). After studying the character of the fields and combining the data of seismic tomography, we attain the conclusions as fallows:(1)the interior storage material inside the Kangdian lozenge block in Sanjiang region stems from the material in the Qinghai-Tibet Plateau and has close dependence on the Qinghai Tibet Plateau;(2)the thickness of the low velocity layer in Kangdian lozenge block is larger than that in other area around the block;(3)seismogenic zone is located usually in the place of inflexion of gravity anomaly contour, especially in complexly changing zone.