1970年通海7.7级大地震强余震触发
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摘要
1970年1月5日云南通海发生了MS7.7地震,震后发生了多次MS>5.0的强余震。文中计算了1970年通海7.7级大地震后,主震分别在5次强余震破裂面上诱发的库仑破裂应力变化(ΔCFS)。结果表明,有4次强余震发生在库仑破裂应力增加(ΔCFS>0)的地区,增加的范围为10-2～10-1MPa;有1次强余震按2种震源机制解结果给出的破裂面计算,得到2种结果,分别发生在库仑破裂应力变化为正和在库仑破裂应力变化为负的地区。研究结果表明,主震位错产生的库仑破裂应力变化可能是1970年通海7.7级大地震强余震活动的重要原因。
The Tonghai great earthquake occurred on Jan. 5, 1970 in Yunnan Province. After the main shock, several large aftershocks (M_S>5.0) occurred. Calculations of the change in Coulomb failure stress on aftershock failure plane reveal that 4 events among 5 large aftershocks occurred in areas with ΔCFS>0 (10~(-2)～10~(-1) MPa); There are two contrary results for one aftershock due to two different focal mechanism, this aftershock occurred in areas with ΔCFS>0 and ΔCFS<0. It is concluded that the permanent fault displacement due to the main shock is the main causation of activity of large aftershocks.
The Tonghai great earthquake occurred on Jan. 5, 1970 in Yunnan Province. After the main shock, several large aftershocks (M_S>5.0) occurred. Calculations of the change in Coulomb failure stress on aftershock failure plane reveal that 4 events among 5 large aftershocks occurred in areas with ΔCFS>0 (10~(-2)～10~(-1) MPa); There are two contrary results for one aftershock due to two different focal mechanism, this aftershock occurred in areas with ΔCFS>0 and ΔCFS<0. It is concluded that the permanent fault displacement due to the main shock is the main causation of activity of large aftershocks.
引文
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[2] SteinRS,BarkaAA,DieterichJH.ProgressivefailureontheNorthAnatolianfaultsince1939byearthquakestresstriggering[J].GeophysJInt,l997,128,594 604.
[3] ReasenbergPA,SimpsonRW.ResponseofregionalseismicitytothestaticstresschangeproducedbytheLomaPrietaearthquake[J].Science,1992,255:1687 1690.
[4] KingGCP,SteinRS,LinJ.Staticstresschangesandthetriggeringofearthquakes[J].BullSeismSocAmer,1994,84:935 953.
[5] HardebeckJL,NazarethJJ,HaukssonE.Thestaticstresschangetriggeringmodel:ConstraintsfromtwosouthernCaliforniaaftershocksequences[J].JGeophysRes,1998,98:4461 4472.
[6] TodaS.Stresstransferredbythe1995Mw=6.9Kobe,Japan,shock:Effectonaftershocksandfutureearthquakeprobabilities[J].JGeophysRes,1998,103:24543 24565.
[7] 刘桂萍,傅征祥.1973年炉霍大地震(MS=7.6)最大余震(MS=6.3)的库仑破裂应力触发[J].中国地震,2002,18(2):175 182.
[8] 万永革,吴忠良,周公威,等.几次复杂地震中不同破裂事件之间的"应力触发"问题[J].地震学报,2000,22(6):568 576.
[9] SimpsonRW,ReasenbergPA.Earthquake-inducedstaticstresschangesoncentralCaliforniafaults[A].In:SimpsonRWeds.TheLomaPrieta,CaliforniaEarthquakeofOctober17,1989 Tectonicprocessesandmodels[C].USGeolSurvProfPap,1994.F55 F89.
[10] SteinRS,KingGCP,LinJ.ChangeinfailurestressonthesouthernSanAndreasfaultsystemcausedbythe1992magnitude=7.4Landersearthquake[J].Science,258:1328 1332.
[11] OkadaY.Internaldeformationduetoshearandtensilefaultsinahalf-space[J].BullSeismSocAmer,1992,82:1018 1040.
[12] 刘祖荫,皇甫岗,金志林.一九七○年通海地震[M].北京:地震出版社,1999.
[13] 王椿镛,朱成男,刘玉权,等.用地形变资料测定通海地震的地震断层参数[J].地球物理学报,1978,21(3):191 198.
[14] 马宗晋,傅征祥,张郢珍,等.1966～1976年中国九大地震[M].北京:地震出版社,1982.
[15] VargaP.Influenceofextermalforceonthetriggeringofearthquakes[J].EarthqPredictionRes,1985,1:191 201.
[16] 马杏垣.重力作用与构造运动[M].北京:地震出版社,1989.
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