安徽及邻区中强震前波速比变化研究
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摘要
利用安徽及邻区地震波的震相资料,根据和达法计算波速比的原理,研发了波速比的计算程序,并对大台网和小台网资料的计算结果进行了对比分析,认为大、小台网资料对波速比的计算结果影响较小。此外还分析了台网布局对计算波速比的影响,发现在计算过程中加入远近台波速比值限制后,波速比变化范围减小,异常时间段也更为清晰,因此在在计算波速比时间进程时需要加远近台波速比限制。本文计算了安徽及周边地区7次中强地震前的波速比时间进程曲线,其中5次地震前存在低波速比异常,同时通过震例总结表明华东地区MS5.5级左右地震选取震中附近3°×3°范围内地震计算波速比、MS4.5级左右地震选取震中附近2°×2°范围内地震计算波速比相对比较合理,与相应强度地震的孕震范围较为吻合。
On basis of seismic phase data in Anhui province and its surrounding area,a velocity ratio of seismic waves(Vp/Vs) calculating program is write according to the Wadati method for calculating velocity ratio of seismic waves(Vp/Vs),and results of the program to data of large seismic network and data of small seismic network are contrastively analyzed.The analysis shows that the scale of seismic network has little effect on the calculating result.In addition,analysis of the effect of spatial distribution of seismic station shows that,the variation range of wave velocity ratio decrease as wave velocity ratio limit according to station distance added the calculating process,and the anomaly period become more clear,and so,it is necessary to add wave velocity ratio limit according to station distance while calculating wave velocity ratio time series.In this paper,7 wave velocity ratio time series before moderate-strong earthquakes are calculated and 5 of them show wave velocity ratio anomaly before the earthquakes,further more,earthquake cases summarizing indicates that in Eastern China,it is relatively reasonable to adopt 3°×3°area around the epicenter of a MS5.5 earthquake and 2°×2° area around the epicenter of an earthquake of about Ms4.5 while calculating wave velocity ratio.
On basis of seismic phase data in Anhui province and its surrounding area,a velocity ratio of seismic waves(Vp/Vs) calculating program is write according to the Wadati method for calculating velocity ratio of seismic waves(Vp/Vs),and results of the program to data of large seismic network and data of small seismic network are contrastively analyzed.The analysis shows that the scale of seismic network has little effect on the calculating result.In addition,analysis of the effect of spatial distribution of seismic station shows that,the variation range of wave velocity ratio decrease as wave velocity ratio limit according to station distance added the calculating process,and the anomaly period become more clear,and so,it is necessary to add wave velocity ratio limit according to station distance while calculating wave velocity ratio time series.In this paper,7 wave velocity ratio time series before moderate-strong earthquakes are calculated and 5 of them show wave velocity ratio anomaly before the earthquakes,further more,earthquake cases summarizing indicates that in Eastern China,it is relatively reasonable to adopt 3°×3°area around the epicenter of a MS5.5 earthquake and 2°×2° area around the epicenter of an earthquake of about Ms4.5 while calculating wave velocity ratio.
引文
[1]冯德益.地震波速异常[M].北京:地震出版社,1981.
[2]许绍燮,陆远忠,朱传镇,等.地震学专辑[M].北京:学术书刊出版社,1989:379-394.
[3]国家地震局科技监测司.地震学分析预报方法程式指南[M].北京:地震出版社,1990:45-47.
[4]刁桂苓,周仕勇,刘杰,等.岫岩地震序列的平均波速比前兆异常[J].华北地震科学,2005,23(4):1-5.
[5]张小涛,吕坚,马广庆,等.九江-瑞昌地震序列的波速比特征研究[J].华北地震科学,2006,24(4):36-40.
[6]王林瑛,郭永霞,刘芳,等.文安地震前后首都圈分区波速比时变特征[J].地震学报,2008,30(3):240-253.
[7]林眉,王洪水,冀东普,等.菏泽—濮阳及附近地区震源深度及波速比变化[J].华北地震科学,2010,(1):31-35.
[8]李敏莉,刘东旺,刘泽民,等.安徽及邻区平均波速比的测定及研究[J].地震地磁观测与研究,2005,26(1):22-27.
[2]许绍燮,陆远忠,朱传镇,等.地震学专辑[M].北京:学术书刊出版社,1989:379-394.
[3]国家地震局科技监测司.地震学分析预报方法程式指南[M].北京:地震出版社,1990:45-47.
[4]刁桂苓,周仕勇,刘杰,等.岫岩地震序列的平均波速比前兆异常[J].华北地震科学,2005,23(4):1-5.
[5]张小涛,吕坚,马广庆,等.九江-瑞昌地震序列的波速比特征研究[J].华北地震科学,2006,24(4):36-40.
[6]王林瑛,郭永霞,刘芳,等.文安地震前后首都圈分区波速比时变特征[J].地震学报,2008,30(3):240-253.
[7]林眉,王洪水,冀东普,等.菏泽—濮阳及附近地区震源深度及波速比变化[J].华北地震科学,2010,(1):31-35.
[8]李敏莉,刘东旺,刘泽民,等.安徽及邻区平均波速比的测定及研究[J].地震地磁观测与研究,2005,26(1):22-27.
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