天祝-古浪5.4级地震前后波谱异常特征研究
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摘要
使用ＣＤＳＮ 兰州台数字地震记录资料，用ＩＡＳＰＥＩ推荐的Ｓｅｉｓｇｒａｍ 谱分析软件，对１９９６年６ 月１ 日发生在甘肃天祝－古浪ＭＳ ５．４ 地震之前的３ 个前震和１４ 个余震的波谱特征作了初步研究：①在主震后地震的纵横波零频位移谱值的对数比值从１．２ 左右下降到１．０ 左右；②纵横波谱的拐角频率比值和高频衰减斜率比值均由主震前的１．０ 下降到主震后的０．８；③各频谱特征量呈现异常的时间基本上同步，其异常形态也相似；④前震的各频谱特征量较余震有明显差异，因而有可能成为预测主震的重要指标。
On June 1, 1996, an earthquake (M S=5.4) occurred in Tianzhu Gulang region, Gansu Province. In this paper, the short period digital seismic data at CDSN Lanzhou station was processed by Seismgram software, which is recommend by IASPEI. The wave spectra of three foreshocks and fourteen after shocks of Tianzhu Gulang M S 5.4 earthquake were studied. The results are shown as follows:① The logarithm ratio value of level of zero sequence of displacement spectrum reduced from 1.2 before mainshock to 1.0 after mainshock.② The corner frequency ratio value and the high sequence spectrum of oblique factor ratio value reduced from 1.0 before mainshock to 0.8 after mainshock.③ The every characteristic curve of wave spectrum shows same form in the same anomaly period.④ There are remarkable anomaly characteristics before and after the mainshock. So it may become an important index for earthquake prediction.
On June 1, 1996, an earthquake (M S=5.4) occurred in Tianzhu Gulang region, Gansu Province. In this paper, the short period digital seismic data at CDSN Lanzhou station was processed by Seismgram software, which is recommend by IASPEI. The wave spectra of three foreshocks and fourteen after shocks of Tianzhu Gulang M S 5.4 earthquake were studied. The results are shown as follows:① The logarithm ratio value of level of zero sequence of displacement spectrum reduced from 1.2 before mainshock to 1.0 after mainshock.② The corner frequency ratio value and the high sequence spectrum of oblique factor ratio value reduced from 1.0 before mainshock to 0.8 after mainshock.③ The every characteristic curve of wave spectrum shows same form in the same anomaly period.④ There are remarkable anomaly characteristics before and after the mainshock. So it may become an important index for earthquake prediction.
引文
1 许健生,尹志文.共和地震前后中小地震的波谱变化.地震地磁观测与研究,1998,19(4):30～36
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5 冯德益.地震波速异常.北京:地震出版社,1981.15～20
6 Burne JN.Tectonic strees and the spectra of seism ic shear w aves from eathquakes.JG R,1970,75:4997～5009
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8 罗娣华,叶建庆,陈敏恭,等.丽江7.0级地震的余震震源参数研究.地震研究,1977,20:83～90
2 Keilis-Borok V I.Differences in the spectra ofsurface w aves from earthquakes and form explosions.TrInstFiz.Zem li,1961,15(182):88～101
3 RandallM J.Elastic m ultipe theory and Seism ic m om ent.BSSA,1971,61:1321～1326
4 冯德益,谭爱娜,王克芬.近地震波波速异常与地震预报.地球物理学报,1974,17(2):84～97
5 冯德益.地震波速异常.北京:地震出版社,1981.15～20
6 Burne JN.Tectonic strees and the spectra of seism ic shear w aves from eathquakes.JG R,1970,75:4997～5009
7 Hanks T C, w yss M.The use ofbody w ave spectra in the determ ination ofseism ic- source param eters.BSSA,1972,62:561～589
8 罗娣华,叶建庆,陈敏恭,等.丽江7.0级地震的余震震源参数研究.地震研究,1977,20:83～90
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