【摘要】 利用兰州数字地震遥测台网观测报告,采用和达法计算出2001年1月—2007年6月发生在青藏块体东北缘2 953次地震的波速比值。将青藏块体东北缘按1°×1°、0.2°×0.2°分成小区,求出每个小区域内的平均波速比值。分析得出如下结论:(1)青藏块体东北缘平均波速比值在空间分布上有一定差异,甘东南(N34°以南)波速比值最高,祁连山地震带和西秦岭北缘断裂附近次之,甘肃中部最低;(2)青藏块体东北缘矿震分布区域和1°×1°的低波速比值区域一致,地震波速比值是判定矿震的可能依据之一;(3)地震波速比值随震级的增大而增大。所得的平均波速比值为研究青藏块体东北缘波速比值随时间变化有一定参考价值。更多还原

【Abstract】 Based on the Lanzhou seismic network observational report,using the multi-station methods,the seismic velocity ratio(VP/VS) of the 2 953 earthquakes in Northeastern margin of Qinghai-Tibet block during Jan.2001 to Jun.2007 are calculated.The research region are divided into little areas by 1°×1° and 0.2°×0.2°,and the average seismic velocity ratios for every little areas are given.Through analysising the average seismic velocity ratios,following conclusion are gottern:(1) The average ratios in different regions of the research block are different,among them,the ratio in Southeastern of Gansu province is the highest,in Qilian seismic belt and along West Qinling fault are higher also,in middle Gansu province is the lowest.(2) The mine earthquakes often occurred in the 1°×1° little areas with lower ratios,so the ratio could be used to distinguish mine earthquake.(3) The ratio values increase along with the increase of magnitudes of earthquake.The average seismic velocity ratios for each area in Northeastern margin of Qinghai-Tibet block can be a reference to analyze the variation of the ratio before strong earthquakes.更多还原