云南地区地震序列的波速比(V_P/V_S)异常研究
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摘要
针对2000年姚安6.5级、2001年施甸5级、2001年永胜6.0级和2003年大姚6.2、6.1级地震序列,分别采用多台法和固定台站方法计算了这些地震序列的波速比。由于采用的均是数字波形资料,到时读取精度达到0.02s。考虑台站因素,计算波速比的置信度最低达到95%。文中讨论强余震之前波速比的变化特征,发现强余震前出现波速比趋势性下降的特征,这对强余震的短临预测有实用价值;主震发生时和发生以后波速比的波动范围的对比,对震区的震情趋势判定有一定的指示和参考。
The multi-station method and fixed-station method are applied to calculate velocity ratio of four earthquake sequences,which are Yao′an M6.5 in 2000,Shidian M5.0 in 2001,Yongsheng M6.0 in 2001 and Dayao M6.2,M6.1 earthquake sequences in 2003.The accuracy for reading arrival time of waveform is 0.02 seconds when using digital data.The confidence is at least 95% on calculating velocity ratio when considering station factor.The results show that there is a decreasing trend of velocity ratio before strong aftershocks.It is of practical value on the short-imminent term prediction of strong aftershocks.In addition,the comparison of the variation range of velocity ratio between the time when mainshock occurs and the time after mainshock can be as a reference index on studying seismic tendency of earthquake sequence.
The multi-station method and fixed-station method are applied to calculate velocity ratio of four earthquake sequences,which are Yao′an M6.5 in 2000,Shidian M5.0 in 2001,Yongsheng M6.0 in 2001 and Dayao M6.2,M6.1 earthquake sequences in 2003.The accuracy for reading arrival time of waveform is 0.02 seconds when using digital data.The confidence is at least 95% on calculating velocity ratio when considering station factor.The results show that there is a decreasing trend of velocity ratio before strong aftershocks.It is of practical value on the short-imminent term prediction of strong aftershocks.In addition,the comparison of the variation range of velocity ratio between the time when mainshock occurs and the time after mainshock can be as a reference index on studying seismic tendency of earthquake sequence.
引文
[1]冯德益.地震波速异常[M].北京:地震出版社,1981.14-15.
[2]Aggarwal Y P,Sykes L R,Ambruster J,et al.Premonitory changes in seismic velocities and pre-diction of earthquakes[J].Nature,1973,241(5385):101-104.
[3]Whitcomb J H,Garmany J D,Anderson D L.Earthquake prediction:variation of seismic velocitiesbefore the San Fernando earthquake[J].Science,1973,180:632-641.
[4]Kisslinger C,Enggahl E R.The interpretation of the Wadati diagram with relaxed assumptions[J].BSSA,1973,63(5):1 723-1 736.
[5]Gupta I N.Premonitory seismic-wave phenomena before earthquakes near Fairview Peak,Nevada[J].BSSA,1975,65(2):425-437.
[6]徐果明,周惠兰.地震学原理[M].北京:科学出版社,1982,426-427.
[7]梅世蓉,冯德益,张国民,等.中国地震预报概论[M].北京:地震出版社,1993.78-80.
[8]冯德益.地震波理论与应用[M].北京:地震出版社,1988.417-430.
[9]陆远忠,陈章立.地震预报的地震学方法[M].北京:地震出版社,1985.
[10]Wadati K.Shallow and deep earthquakes[J].Geophysical Magazine,1928,1:162-202.
[11]冯德益.地震波速异常[M].北京:地震出版社,1981.21-23,36-37.
[12]黎明晓,张晓东.应用多台法测定华北地区地壳的平均波速比[J].地震,2004,24(1):163-169.
[2]Aggarwal Y P,Sykes L R,Ambruster J,et al.Premonitory changes in seismic velocities and pre-diction of earthquakes[J].Nature,1973,241(5385):101-104.
[3]Whitcomb J H,Garmany J D,Anderson D L.Earthquake prediction:variation of seismic velocitiesbefore the San Fernando earthquake[J].Science,1973,180:632-641.
[4]Kisslinger C,Enggahl E R.The interpretation of the Wadati diagram with relaxed assumptions[J].BSSA,1973,63(5):1 723-1 736.
[5]Gupta I N.Premonitory seismic-wave phenomena before earthquakes near Fairview Peak,Nevada[J].BSSA,1975,65(2):425-437.
[6]徐果明,周惠兰.地震学原理[M].北京:科学出版社,1982,426-427.
[7]梅世蓉,冯德益,张国民,等.中国地震预报概论[M].北京:地震出版社,1993.78-80.
[8]冯德益.地震波理论与应用[M].北京:地震出版社,1988.417-430.
[9]陆远忠,陈章立.地震预报的地震学方法[M].北京:地震出版社,1985.
[10]Wadati K.Shallow and deep earthquakes[J].Geophysical Magazine,1928,1:162-202.
[11]冯德益.地震波速异常[M].北京:地震出版社,1981.21-23,36-37.
[12]黎明晓,张晓东.应用多台法测定华北地区地壳的平均波速比[J].地震,2004,24(1):163-169.
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