半几何方法及其在汶川8.0级地震中的应用
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摘要
利用计算与画图相结合的半几何方法,对汶川M8.0级地震主震及其部分余震的震中位置和发震时刻进行了重新计算,并与四川台地震网定位结果进行比较,对比结果显示,震中位置的误差范围在±4.5 km以内,一般在±2.5 km;发震时刻误差范围在3秒以内,结果的可靠性较好。计算过程中消去了深度项,因此无法确定震源深度。它适用于近震,对小台网或小动态范围仪器记录确定震中位置很方便。该方法无需速度模型,其结果可用来检验区域速度模型。
The semi-geometry method is based on calculation and drawing. It does not need the speed model of seismic waves but do need accurate picking up the arrival times of direct waves with same seismic waves which are recorded in several stations. The parameters of epicenter traces are firstly calculated and then the lines are drawn and so the epicenter can be determined by the intersection point with lines and the origin time of earthquake is also determined. However,the focal depth cannot be determined. In this research,this method is used to calculate the epicenter and the original times of main shock and its aftershocks with different magnitude of the 2008 M8. 0 Wenchuan Earthquake and it has good results. The semi-geometry method is applied to the near earthquakes and is convenient for determining the epicenter in small networks or with records from instruments which has small dynamic range. It can also be used to test whether area velocity model is suitable.
The semi-geometry method is based on calculation and drawing. It does not need the speed model of seismic waves but do need accurate picking up the arrival times of direct waves with same seismic waves which are recorded in several stations. The parameters of epicenter traces are firstly calculated and then the lines are drawn and so the epicenter can be determined by the intersection point with lines and the origin time of earthquake is also determined. However,the focal depth cannot be determined. In this research,this method is used to calculate the epicenter and the original times of main shock and its aftershocks with different magnitude of the 2008 M8. 0 Wenchuan Earthquake and it has good results. The semi-geometry method is applied to the near earthquakes and is convenient for determining the epicenter in small networks or with records from instruments which has small dynamic range. It can also be used to test whether area velocity model is suitable.
引文
[1]惠少兴,张元生,李顺成.t-D地震定位方法研究[J].西北地震学报,2012,34(1):10-13.
[2]王长在,吴建平,房立华,等.2009年姚安地震序列定位及震源区三维P波速度结构研究[J].地震学报,2011,33(2):123-133.
[3]蔡明军,山秀明,徐彥,等.从误差观点综述分析地震定位方法[J],地震研究,2004,27(4):314-317.
[4]刘斌.地震学原理与应用[M].合肥:中国科学技术大学出版社,2009:30-33.
[5]中国科学院地球物理研究所.近震分析[M].北京:地震出版社,1977:56-61.
[6]张小平,李铁,李涯,等.测定震源位置的半几何方法在大连遥测地震台网中的应用[J].防灾减灾学报,1995,11(2):90-96.
[7]刘博研,史保平,雷建设.汶川地震对芦山地震及周边断层发震概率的影响[J].地震学报,2013,35(5):642-651.
[2]王长在,吴建平,房立华,等.2009年姚安地震序列定位及震源区三维P波速度结构研究[J].地震学报,2011,33(2):123-133.
[3]蔡明军,山秀明,徐彥,等.从误差观点综述分析地震定位方法[J],地震研究,2004,27(4):314-317.
[4]刘斌.地震学原理与应用[M].合肥:中国科学技术大学出版社,2009:30-33.
[5]中国科学院地球物理研究所.近震分析[M].北京:地震出版社,1977:56-61.
[6]张小平,李铁,李涯,等.测定震源位置的半几何方法在大连遥测地震台网中的应用[J].防灾减灾学报,1995,11(2):90-96.
[7]刘博研,史保平,雷建设.汶川地震对芦山地震及周边断层发震概率的影响[J].地震学报,2013,35(5):642-651.
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