青海共和7.0级强震的前兆异常与时空分布
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摘要
在研究了 1 990年 4月 2 6日共和 7.0级强震前 ,青海东北部地区的小震活动和前兆异常总台频次的变化 ,以及地下流体 ,电磁 ,形变等前兆异常的时空演化特征的基础上 ,得出在大震前 1～ 7个月前兆异常台项总频次的升高和 2 .0～ 3.9级地震形成的条带和空区 ,以及 3.5级以上地震频次增加在时间上是同步的。而且 ,2 .0～ 3.9级地震形成的条带和空区对未来大震的震中位置具有指示意义。这种前兆异常在时间上的同步性可能是大震前的异常由中期向短期过渡的时间标志 ,震前 2个月出现的前兆台项总频次异常峰值以及形变前兆异常场兆变化则是异常进入短临的时间。
On the basis of the study of small earthquake activity,the variation of total frequency of precursor anomaly and temporal spatial evolution of subsurface fluid,electromagnetism,deformation before M 7 0 Gonghe strong earthquake on April 26,1990,we obtained that from one to seven months before the large earthquake,the increase in total frequency number of precursor anomaly,stripes and gaps of earthquakes with M 2 0～3 9 and obvious increase of frequency numbers of earthquakes with M ≥3 5 are synchronous. The stripes and gaps of earthquake activity with M 2 0～3 9 are significant to determine epicentre of forthcoming large earthquake.It may be time mark from medium term to short term before large earthquake that precursor anomaly is synchronous at time.And two months before an earthquake there are high value of total frequency in precursor and variation of deformation.
On the basis of the study of small earthquake activity,the variation of total frequency of precursor anomaly and temporal spatial evolution of subsurface fluid,electromagnetism,deformation before M 7 0 Gonghe strong earthquake on April 26,1990,we obtained that from one to seven months before the large earthquake,the increase in total frequency number of precursor anomaly,stripes and gaps of earthquakes with M 2 0～3 9 and obvious increase of frequency numbers of earthquakes with M ≥3 5 are synchronous. The stripes and gaps of earthquake activity with M 2 0～3 9 are significant to determine epicentre of forthcoming large earthquake.It may be time mark from medium term to short term before large earthquake that precursor anomaly is synchronous at time.And two months before an earthquake there are high value of total frequency in precursor and variation of deformation.
引文
梅世蓉 . 1 996.地震前兆场物理模式与前兆时空分布机制研究 .地震学报 ,1 8(1 ) :1～ 9
王华林 ,王晋南 ,杨桂芬 . 1 999.前兆异常与强震时空点的研究 .地震学报 ,2 2 (3) :2 2 1～ 2 2 3
王华林 ,王晋南 ,杨桂芬 . 1 999.前兆异常与强震时空点的研究 .地震学报 ,2 2 (3) :2 2 1～ 2 2 3
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