地震研究

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4 279个中小地震进行精确定位,获得了4 124个地震基本参数,走时残差均方根的平均值由定位前的0.502 s降到了0.086 s。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3～15 km,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 together underground.

引言
1 方法简介
2 资料选取
3 定位过程和定位结果
4 结论与讨论

图1 1979年以来云南地区架设的地震台站分布示意图<br/>Fig.1 Distribution of stations set up in Yunnan since 1979

图1 1979年以来云南地区架设的地震台站分布示意图
Fig.1 Distribution of stations set up in Yunnan since 1979

表1 澜沧—耿马地区水平层状地壳速度模型<br/>Tab.1 Velocity model of horizontal and layered crust in Lancang-Gengma area

表1 澜沧—耿马地区水平层状地壳速度模型
Tab.1 Velocity model of horizontal and layered crust in Lancang-Gengma area

图2 重定位前后的震中分布(蓝色:Hypo2000定位结果; 红色:双差定位结果)<br/>Fig.2 Epicenter distribution before and after relocation(blue:positioning by Hypo2000; red:positioning by HypoDD)

图2 重定位前后的震中分布(蓝色:Hypo2000定位结果; 红色:双差定位结果)
Fig.2 Epicenter distribution before and after relocation(blue:positioning by Hypo2000; red:positioning by HypoDD)

图3 震源深度剖面(a)重定位前沿AB方向震源深度剖面;(b)重定位后沿AB方向的震源深度剖面
Fig.3 Focal depth profile(a)Focal depth profile along the A-B direction before the relocation;(b)Focal depth profile along the A-B direction after the relocation

图4 沿不同方向的震源深度剖面图
(a)沿C1—C2方向的震源深度剖面;(b)沿D1—D2方
向的震源深度剖面;(c)沿E1—E2方向的震源深度
剖面;(d)沿F1—F2方向的震源深度剖面;
(e)沿G1—G2方向的震源深度剖面
Fig.4 Focal depth profile along different directions(a)Focal depth profile along the C1-C2 direction;(b)Focal depth profile along the D1-D2 direction;(c)Focal depth profile along the E1-E2 direction;(d)Focal depth profile along the F1-F2 direction;(e)Focal

图5 澜沧—耿马地区地质构造图(图中圆圈表示地震)(毛玉平,韩新民,2003)<br/>Fig.5 Geologic structure in Lancang-Gengma area(Circle refers to earthquake)(Mao,Han,2003)

图5 澜沧—耿马地区地质构造图(图中圆圈表示地震)(毛玉平,韩新民,2003)
Fig.5 Geologic structure in Lancang-Gengma area(Circle refers to earthquake)(Mao,Han,2003)

表2 澜沧—耿马地震序列部分地震震源机制(王绍晋等,1993)<br/>Tab.2 Table of focal mechanism of several earthquckes in the Lancang-Gengma earthquake sequences(Wang et al,1993)

表2 澜沧—耿马地震序列部分地震震源机制(王绍晋等,1993)
Tab.2 Table of focal mechanism of several earthquckes in the Lancang-Gengma earthquake sequences(Wang et al,1993)

虢顺民,向宏发,周瑞奇,等.1999.滇西南龙陵—澜沧断裂带——大陆地壳上一条新生的破裂带[J].科学通报,44(19):2118-2121.
姜葵.1993.1988年云南澜沧—耿马地震[M].昆明:云南大学出版社.
林中洋,胡鸿翔,张文彬,等.1993.滇西地区地壳上地幔速度结构特征的研究[J].地震学报,15(4):427-440.
毛玉平,韩新民.2003.云南地区强震(M≥6)研究[M].昆明:云南科技出版社.
王绍晋,阚荣举,宋文,等.1993.澜沧—耿马地震孕育过程中应力场时空变化与预测检验[J].地震研究,16(2):111-112.
杨智娴,陈运泰,张宏志.1999.张北—尚义地震序列的重新定位[J].地震地磁观测与研究,20(6):6-9.
杨智娴,陈运泰,张宏志.2002.张北—尚义地震序列的重新定位和发震构造[J].地震学报,24(4):366-377.
杨智娴,陈运泰,郑月军等.2003.双差地震定位法在我国中西部地区地震精确定位中的应用[J].中国科学,33(增刊):129-134.
Geiger L.1912.Probability method for the determination of earthquake epicenters from arrival time only[J].Bull St Louis Univ,8:60-71.
Klein F W.2007.User's Guide to HYPOINVERSE-2000:a Fortran Program to Solve for Earthquake Locations and Magnitudes [EB/OL].U S Geological Survy Open File Report,(2011-01-12)[2000-04-22],http://www.ipgp.fr/～arnaudl/NanoCD/documentation/ 3rdParty/hyp2000-1.0.pdf.
Waldhauser F,Ellsworth W L.2000.A Double-Difference Earthquake Location Algorithm:Method and Application to the Northern Hayward fault,California [J].BSSA,90(6):1353-1368.

备注

引言

1 方法简介

2 资料选取

3 定位过程和定位结果

4 结论与讨论

期刊信息