利用四川测震台网记录的芦山余震资料,选取20个M ≥ 2.5地震,以Loc3D (川滇)定位方法定位结果为标准。采用MSDP中常用定位方法(HypoSAT、HYP2000、LocSAT、单纯型),在人为增减台站情况下,使得台站空隙角在25°-320°范围内任意变化,采用相同震相和相同台站对选定的地震事件进行定位,并对定位结果与标准结果对比,结果表明:震中位置在台站空隙角25°-130°任意变化时,4种定位方法效果较好,差别不大;在空隙角达到130°时,震中位移具有随着空隙角增大而逐步变大趋势;在空隙角达到190°时,单纯型法震中位移明显加大,出现随机突跳现象。总体而言,LocSAT法定位效果较好,平均震中位移2.6 km,HYP2000法平均震中位移2.8 km,HypoSAT平均震中位移4.1 km,单纯型定位效果较差,平均震中位移10.3 km。
Using the seismic data of 20 M=2.5 earthquakes selected from Lushan aftershocks, which were recorded by the Sichuan seismic network, taking the positioning results of Loc3D (Sichuan and Yunnan) positioning method as the standard, the positioning results of conventional positioning method in MSDP (HypoSAT, HYP2000, locSAT, Simplex method), are comparative analyzed on the conditions of artifcially choosing stations to make the station space angle arbitrarily changed at 25°-320° range, and using the same phase and the same stations. The positioning results show that, in the space station angle arbitrarily changed in the range of 25°-130°, the position effects of 4 kinds of positioning methods had no signifcant difference; in the gap at an angle of 130°, the displacement angle increases with the gap and shows a trend of gradually increasing with the gap; at an angle of 190°, the displacement of simplex method increases obviously with random jump phenomenon. Overall, the LocSAT method is of good positioning effect, average epicentral displacement is 2.6 km, the average epicentral displacement of HYP2000 is 2.8 km and the average epicentral displacement of HypoSAT is 4.1 km, the simplex method is of poor position effect, its average epicenter displacement is 10.3 km.
2017,38(3): 53-59 收稿日期:2017-01-05
DOI:10.3969/j.issn.1003-3246.2017.03.010
基金项目:中国地震局"三结合"课题(项目编号:162302);四川省地震局地震科技专项(项目编号:LY1607)
作者简介:管勇(1972-),男,工程师,主要研究方向:地震定位。E-mail:1143200213@qq.com.
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