地震动态触发机制的初步研究
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摘要
提出地震的动态触发摸式 .用三维非线性动态有限元方法研究了地震的动态触发的可能机制 .模拟结果表明 ,应力波在反射后发生半波损失 ,压缩波可以转变成拉伸波 ,反之亦然 .因此 ,动应力包含有拉伸应力 .拉伸波叠加或干涉形成较大的动态应力 ,减小围压 ,因此减小了内摩擦力 ,从而触发地震 .研究表明断层形态会影响动态应力 ,认为地震触发的位置与孕震体边界形状有关 .本文还结合有关地学理论和资料 ,对以上结果进行了相应的分析并给出物理解释 .
We propose a possible dynamic mechanism of earthquake triggering. Three dimensional nonlinear FEM is adopted to study the mechanism and the dynamic process of earthquake triggering. Simulation result shows that the dynamic mechanism is quite different from the static one. Especially, the reflected compressive waves, having lost half wavelength, become tensile ones which can be superposed each other to double the tensile stress and cause a rupture. Considering the giant ambient pressure, therefore, the mechanism may be like this: the tensile stress reduces the ambient compressive static stress to reduce the inner friction and cause an earthquake. Study suggests that triggering position should be relied on the boundary shape of a rock body. And an interpretation is given by a joint analysis in conjunction with observations.
We propose a possible dynamic mechanism of earthquake triggering. Three dimensional nonlinear FEM is adopted to study the mechanism and the dynamic process of earthquake triggering. Simulation result shows that the dynamic mechanism is quite different from the static one. Especially, the reflected compressive waves, having lost half wavelength, become tensile ones which can be superposed each other to double the tensile stress and cause a rupture. Considering the giant ambient pressure, therefore, the mechanism may be like this: the tensile stress reduces the ambient compressive static stress to reduce the inner friction and cause an earthquake. Study suggests that triggering position should be relied on the boundary shape of a rock body. And an interpretation is given by a joint analysis in conjunction with observations.
引文
1)中国地震局综合观测中心,2003年震情趋势研究报告
2)中国地震局地壳应力研究所易志刚提供
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[2]NurA .DilatancyPorefluidsandpremonitoryvariationsofts tptraveltimes.Bull.Seism.Soc.Amer.,1972,62(5):1217～1222
[3]MyachkinVI,BraceWF ,SobolevGA ,etal.Twomodelsforearthquakeforerunners.PureandAppliedGeophysics,1975,113(1-2):169～182
[4]郭增建,秦保燕,徐文耀等.震源孕育模式的初步讨论.地球物理学报,1973,16:43～48GuoZJ ,QinBY ,XuWY ,etal.Preliminarystudyonamodelforthedevelopmentofthefocusofanearthquake.ChineseJ .Geophys.(inChinese),1973,16:43～48
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[6]HillDP ,ReasenbergPA ,MichaelA ,etal.Seismicityremotelytriggeredbythemagnitude73Landers,California,earthquake.Science,1993,260:1617～1623
[7]KilbD ,GombergJ,BodinP .Earthquaketriggeringbydynamicstresses.Nature,2000,408:570～574
[8]ByerleeJ .Modelforepisodicflowofhighpresurewaterinfaultzonesbeforeearthquakes.Geology,1993,21:303～306
[9]GombergJ.Thefailureofearthquakefailuremodels.J.Geophys.Res.,2001,106(B8):16253～16263
[10]韩竹军,谢富仁,万永革.断层间相互作用与地震触发机制的研究进展.中国地震,2003,19(1):67～76HanZJ,XieFR ,WanYG .Progressonfaultinteractionandearthquaketriggeringmechanism.EarthquakeResearchinChina(inChinese),2003,19(1):67～76
[11]万永革,吴忠良,周公威等.地震应力触发研究.地震学报,2002,24(5):533～551WanYG ,WuZL ,ZhouGW ,etal.Researchonseismicstresstriggering.ActaSeismologicaSinica(inChinese),2002,24(5):533～551
[12]陆明勇,郑文衡.地壳块体动应力演化特征及其与地震关系的初步研究.地震学报,待刊LuMY ,ZhengWH .Thecharacteristicofdynamicstressevolutionandpreliminaryresearch.ActaSeismologicaSinica(inChinese),tobepressed
[13]HarrisRA .Introductiontospecialsession:Stresstriggers,stressshadows,andimplicationsforseismichazard.J .Geophys.Res.,1998,103:24347～24358
[14]唐春安,徐小荷.岩石破裂的前兆变形率、前兆应力降及临震前兆.地壳形变与地震,1990,10(3):12～18TangCA ,XuXH .Precursorydeformationrateandstressdropinfractureexperimentsofbrittlerocksandearthquakeprecursory.CrustalDeformationandEarthquake(inChinese),1990,10(3):12～18
[15]徐锡伟,陈文彬,于贵华等.2001年11月14日昆仑山库湖地震(MS =81)地表破裂带的基本特征.地震地质,2002,24(1):1～14XuXW ,ChenWB ,YuGH ,etal.CharacteristicfeaturesofthesurfacefracturesoftheHohSaiHu(Kunlunshan)earthquake (MS81)northernTibetanplateau,China.SeismologyandGeology(inChinese),2002,24(1):1～14
[16]陈 兵,江在森,车 时等.玛尼79级地震对昆仑山口西81级地震的触发作用及动力背景初探.中国地震,2003,19(1):1～7ChenB ,JiangZS ,CheS ,etal.StudyoftriggeringactionbetweenMani(MS79)andKunlun(MS81)greatearthquakesandtheirdynamicbackground.EarthquakeResearchinChina(inChinese),2003,19(1):1～7
[17]中国地震局监测预报司编.2001年昆仑山口西81级大地震.北京:地震出版社,2002DepartmentofMonitoringForecast,ChinaEarthquakeAdministration.TheWestoftheKunlunMountainPassMS81LargeEarthquakeintheQinghaiXizangPlateauin2001(inChinese)Beijing:SeismologicalPress,2002
[18]石特临,郭大庆.地震学中非线性预测方法的初步研究.地球科学进展,1995,10(3):273～277ShiTL ,GuoDQ .Preliminarystudyofnonlinearpredictionmethodinseismology.AdvanceinEarthSciences(inChinese),1995,10(3):273～277
[19]陆明勇,牛安福,周峥嵘.强震中短期阶段断层活动时空演化特征的讨论.地震,2003,23(4):1～9LuMY ,NiuAF ,ZhouZR .Discussiononspatio temporalevolutionarycharacteristicsoffaultingactivityinthemiddle shortperiodofstrongearthquake.Eearthquake(inChinese),2003,23(4):1～9
[20]何世海.华北地震场和源地壳形变前兆研究.地震,1995,15(3):199～207HeSH .StudyontheearthquakesourceandfieldprecursorsofcrustaldeformationinNorthChina.Earthquake(inChinese),1995,15(3):199～207
[21]NurA ,RonH ,ScottiO .Kinematicsandmechanicsoftectonicblockrotations.Slowdeformationandtransmissionofstressintheearth.StevenCCohen,PeterVanicekedited.GeophysicalMonograph.49IUGGSeries,1989,(4):31～46
[22]单新建,何玉梅,朱 燕等.伽师强震群震源破裂特征的初步分析.地球物理学报,2002,45(3):416～425ShanXJ,HeYM ,ZhuY ,etal.ApreliminaryanalysisonrupturecharacteristicsofJiashistrongearthquakeswarm.ChineseJ .Geophys.(inChinese),2002,45(3):416～425
2)中国地震局地壳应力研究所易志刚提供
[1]ReidHF .Theelastic reboundedtheoryofearthquakes.Univ.Calif.Pub.Bull.Dept.Geol.Sci,1910,6:413～444
[2]NurA .DilatancyPorefluidsandpremonitoryvariationsofts tptraveltimes.Bull.Seism.Soc.Amer.,1972,62(5):1217～1222
[3]MyachkinVI,BraceWF ,SobolevGA ,etal.Twomodelsforearthquakeforerunners.PureandAppliedGeophysics,1975,113(1-2):169～182
[4]郭增建,秦保燕,徐文耀等.震源孕育模式的初步讨论.地球物理学报,1973,16:43～48GuoZJ ,QinBY ,XuWY ,etal.Preliminarystudyonamodelforthedevelopmentofthefocusofanearthquake.ChineseJ .Geophys.(inChinese),1973,16:43～48
[5]牛志仁.地震的前兆理论:震源孕育的膨胀蠕动模式.地球物理学报,1978,21(3):199～212NiuZR .Onthetheoryofprecursorsoftectonicearthquakes—Dilatancy creepmodelofearthquakesourcedevelopment.ChineseJ .Geophys.(inChinese),1978,21(3):199～212
[6]HillDP ,ReasenbergPA ,MichaelA ,etal.Seismicityremotelytriggeredbythemagnitude73Landers,California,earthquake.Science,1993,260:1617～1623
[7]KilbD ,GombergJ,BodinP .Earthquaketriggeringbydynamicstresses.Nature,2000,408:570～574
[8]ByerleeJ .Modelforepisodicflowofhighpresurewaterinfaultzonesbeforeearthquakes.Geology,1993,21:303～306
[9]GombergJ.Thefailureofearthquakefailuremodels.J.Geophys.Res.,2001,106(B8):16253～16263
[10]韩竹军,谢富仁,万永革.断层间相互作用与地震触发机制的研究进展.中国地震,2003,19(1):67～76HanZJ,XieFR ,WanYG .Progressonfaultinteractionandearthquaketriggeringmechanism.EarthquakeResearchinChina(inChinese),2003,19(1):67～76
[11]万永革,吴忠良,周公威等.地震应力触发研究.地震学报,2002,24(5):533～551WanYG ,WuZL ,ZhouGW ,etal.Researchonseismicstresstriggering.ActaSeismologicaSinica(inChinese),2002,24(5):533～551
[12]陆明勇,郑文衡.地壳块体动应力演化特征及其与地震关系的初步研究.地震学报,待刊LuMY ,ZhengWH .Thecharacteristicofdynamicstressevolutionandpreliminaryresearch.ActaSeismologicaSinica(inChinese),tobepressed
[13]HarrisRA .Introductiontospecialsession:Stresstriggers,stressshadows,andimplicationsforseismichazard.J .Geophys.Res.,1998,103:24347～24358
[14]唐春安,徐小荷.岩石破裂的前兆变形率、前兆应力降及临震前兆.地壳形变与地震,1990,10(3):12～18TangCA ,XuXH .Precursorydeformationrateandstressdropinfractureexperimentsofbrittlerocksandearthquakeprecursory.CrustalDeformationandEarthquake(inChinese),1990,10(3):12～18
[15]徐锡伟,陈文彬,于贵华等.2001年11月14日昆仑山库湖地震(MS =81)地表破裂带的基本特征.地震地质,2002,24(1):1～14XuXW ,ChenWB ,YuGH ,etal.CharacteristicfeaturesofthesurfacefracturesoftheHohSaiHu(Kunlunshan)earthquake (MS81)northernTibetanplateau,China.SeismologyandGeology(inChinese),2002,24(1):1～14
[16]陈 兵,江在森,车 时等.玛尼79级地震对昆仑山口西81级地震的触发作用及动力背景初探.中国地震,2003,19(1):1～7ChenB ,JiangZS ,CheS ,etal.StudyoftriggeringactionbetweenMani(MS79)andKunlun(MS81)greatearthquakesandtheirdynamicbackground.EarthquakeResearchinChina(inChinese),2003,19(1):1～7
[17]中国地震局监测预报司编.2001年昆仑山口西81级大地震.北京:地震出版社,2002DepartmentofMonitoringForecast,ChinaEarthquakeAdministration.TheWestoftheKunlunMountainPassMS81LargeEarthquakeintheQinghaiXizangPlateauin2001(inChinese)Beijing:SeismologicalPress,2002
[18]石特临,郭大庆.地震学中非线性预测方法的初步研究.地球科学进展,1995,10(3):273～277ShiTL ,GuoDQ .Preliminarystudyofnonlinearpredictionmethodinseismology.AdvanceinEarthSciences(inChinese),1995,10(3):273～277
[19]陆明勇,牛安福,周峥嵘.强震中短期阶段断层活动时空演化特征的讨论.地震,2003,23(4):1～9LuMY ,NiuAF ,ZhouZR .Discussiononspatio temporalevolutionarycharacteristicsoffaultingactivityinthemiddle shortperiodofstrongearthquake.Eearthquake(inChinese),2003,23(4):1～9
[20]何世海.华北地震场和源地壳形变前兆研究.地震,1995,15(3):199～207HeSH .StudyontheearthquakesourceandfieldprecursorsofcrustaldeformationinNorthChina.Earthquake(inChinese),1995,15(3):199～207
[21]NurA ,RonH ,ScottiO .Kinematicsandmechanicsoftectonicblockrotations.Slowdeformationandtransmissionofstressintheearth.StevenCCohen,PeterVanicekedited.GeophysicalMonograph.49IUGGSeries,1989,(4):31～46
[22]单新建,何玉梅,朱 燕等.伽师强震群震源破裂特征的初步分析.地球物理学报,2002,45(3):416～425ShanXJ,HeYM ,ZhuY ,etal.ApreliminaryanalysisonrupturecharacteristicsofJiashistrongearthquakeswarm.ChineseJ .Geophys.(inChinese),2002,45(3):416～425
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