澜沧—耿马地区中小地震精确定位研究

Accurate Location of Small-and Medium-Earthquakes in Lancang And Gengma Area

概述了双差定位方法及其基本原理,并运用该方法对1979～2009年澜沧—耿马地区发生的4279个中小地震进行精确定位,获得了4124个地震基本参数,走时残差均方根的平均值由定位前的0.502s降到了0.086s。定位结果显示震中沿北北西向的构造呈明显的条带状分布,且更加集中于断层附近,在深度上改变了定位前的层状分布现象,震源深度的优势分布为3～15km,表明该区的发震层较浅。虽然地表显示有部分段落不连续,但从深度剖面和震源机制等结果来看,该北北西向的断裂在地下可能是相通的。

After outlining the double-difference earthquake location algorithm, we applied it to the accurate relocation of 4279 small- and medium- earthquakes occurred in Lancang and Gengma area in Yunnan Province from 1979 to 2009, and obtained the parameters of 4124 earthquakes. We found that the root mean square of the travel-time residuals reduced from 0. 502 s to 0. 086 s. The results displayed that the epicenters were stripedly distributed along the NNW-trend structure. The distribution the earthquake focuses were mainly distributed in the range of 3 - 15 km, which proves that the seismogenic layer in this area was relatively shallow. The original NNW-trend structure seemed discontinuous in the Earth＇s surface, but judging from the depth profile and the focal mechanism. we thought that this structure may be linked tozether underzround.