中国西部北纬35°线附近地区7.0级以上强震分析
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摘要
自1990年以来我国西部及邻近地区先后发生了6次7.0级以上地震,这些地震的震中位于35°N线附近,其纬度界于34.4°~36.2°N之间,平均纬度为35.45°N。美国哈佛大学给出的震源机制表明,这些地震的主压应力轴方位一致性较好,都为NE向,似乎说明这些地震的发生是在统一的应力场作用下的结果,可能与印度板块对我国大陆的推挤作用有关。结合地质构造和余震分布确定了发震断层,计算了它们产生的应力场,根据库仑破裂应力变化,分析了它们之间的相互影响。结果显示,在这些地震中,对后续发生的地震可能具有促震作用。根据引潮力在震源断层面上产生的有效剪切应力,分析了引潮力对这些地震的触发效应,结果没有显示这些地震的发生受到明显的引潮力触发。
There are 6 M>7.0 earthquakes successively occurred in the west of China and nearby regions since 1900.They are located near the 35°N line,and their latitudes range between 34.4°~36.2°N with the average of 35.45°N.According to focal mechanisms given by Harvard University,the azimuths of these earthquake's compression stress axes are almost along the direction of northeast.This paper shows that these earthquake′s occurrences could result from the unified stress field possibly related to the push of the Indian plate to mainland China.We determined their seismic source faults by tectonic fault and the special distribution of the aftershocks,and calculated the stress fields caused by the earthquakes.According to the change of the Coulomb failure stress,we analyzed the interactions of them.The result shows that these s,the former earthquake have triggering effects on subsequent earthquake.According to the effective shear stress on the focal fault plane caused by the earth tide,the triggering effect of the earth tide for these earthquakes is analyzed,the result does not demonstrate that these earthquakes are triggered by earth tide.
There are 6 M>7.0 earthquakes successively occurred in the west of China and nearby regions since 1900.They are located near the 35°N line,and their latitudes range between 34.4°~36.2°N with the average of 35.45°N.According to focal mechanisms given by Harvard University,the azimuths of these earthquake's compression stress axes are almost along the direction of northeast.This paper shows that these earthquake′s occurrences could result from the unified stress field possibly related to the push of the Indian plate to mainland China.We determined their seismic source faults by tectonic fault and the special distribution of the aftershocks,and calculated the stress fields caused by the earthquakes.According to the change of the Coulomb failure stress,we analyzed the interactions of them.The result shows that these s,the former earthquake have triggering effects on subsequent earthquake.According to the effective shear stress on the focal fault plane caused by the earth tide,the triggering effect of the earth tide for these earthquakes is analyzed,the result does not demonstrate that these earthquakes are triggered by earth tide.
引文
[1]郭增建,秦保燕.35度线与大震预报[J].西北地震学报,1991,13(2):93-95.
[2]刘桂萍,傅征祥.1976年7月28日唐山7.8级地震触发的区域地震活动和静应力场变化[J].地震学报,2000,22(6):17-26.
[3]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.
[4]万永革,吴忠良,周公威,等.地震应力触发研究[J].地震学报,2002,24(5):533-550.
[5]万永革,沈正康,甘卫军,等.东昆仑活动断裂带大地震之间的弹性应力触发研究[J].西北地震学报,2003,25(1):1-7
[6]Caskey S J,Wesnousky S G.Static stress changes and earthquake triggering during the 1954 Fai-view Peak and Dixie Valley earthquakes,central Nevada[J].Bull Seism Soc Amer,1997,87:521-527.
[7]Harris R A.Introduction to special section:Stress triggers,stress shadows,and implications forseismic hazard[J].J Geophys Res,1998,103:24 347-24 358.
[8]King G C P,Stein R S,Lin J.Static stress changes and the triggering of earthquakes[J].Bull SeismSoc Amer,1994,84:935-953.
[9]Stein R S,Barka A A,Dieterich J H,et al.Stress transferred by the 1995MW=6.9 Kobe,Japanshock Effect on aftershocks and future earthquake probabilities[J].J Geophys Res,1998,103:24 543-24 565.
[10]丁中一,贾晋康,王仁.潮汐应力对地震的触发作用[J].地震学报,1983,5(2):172-184.
[11]杜品仁.潮汐与地震关系初探[J].地震科学研究,1981,(1):14-20.
[12]高锡铭,殷志山,王威中,等.固体潮应力张量对地震的触发作用[J].地震学报,1981,3(3):264-275.
[13]冯向东,魏东平.地震活动性与日月引潮力相关性统计分析[J].国际地震动态,2007,(5):9-15.
[14]韩延本,李志安,田静.日、月引潮力变化与某些地区地震发生时间的相关研究[J].地球物理学进展,1996,11(2):114-122.
[15]张晶,郗钦文,杨林章,等.引潮力与潮汐应力对强震触发的研究[J].地球物理学报,2007,50(2):448-454.
[16]赵娟,韩延本,李志安.日月引潮力与华北地区的地震[J].地球物理学报,1999,42(增):24-29.
[17]Dix C H.Triggering of some earthquakes[J].Proc Japan Acad,XL,1964,(6):410-415.
[18]Heaton T H.Tidal triggering of earthquakes[J].Bull Seism Soc Amer,1982,72(6):1 811-2 200.
[19]Knopoff L.Earth tides as a triggering mechanism for earthquakes[J].Bull Seism Soc Amer,1964,54:1 865-1 870.
[20]Tsuruoka H,Masakazu O,Haruo S.Statistical test of the tidal triggering of earthquakes;contribu-tion of the ocean tide loading effect[J].Geophys J Int,1995,1:183-194.
[2]刘桂萍,傅征祥.1976年7月28日唐山7.8级地震触发的区域地震活动和静应力场变化[J].地震学报,2000,22(6):17-26.
[3]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.
[4]万永革,吴忠良,周公威,等.地震应力触发研究[J].地震学报,2002,24(5):533-550.
[5]万永革,沈正康,甘卫军,等.东昆仑活动断裂带大地震之间的弹性应力触发研究[J].西北地震学报,2003,25(1):1-7
[6]Caskey S J,Wesnousky S G.Static stress changes and earthquake triggering during the 1954 Fai-view Peak and Dixie Valley earthquakes,central Nevada[J].Bull Seism Soc Amer,1997,87:521-527.
[7]Harris R A.Introduction to special section:Stress triggers,stress shadows,and implications forseismic hazard[J].J Geophys Res,1998,103:24 347-24 358.
[8]King G C P,Stein R S,Lin J.Static stress changes and the triggering of earthquakes[J].Bull SeismSoc Amer,1994,84:935-953.
[9]Stein R S,Barka A A,Dieterich J H,et al.Stress transferred by the 1995MW=6.9 Kobe,Japanshock Effect on aftershocks and future earthquake probabilities[J].J Geophys Res,1998,103:24 543-24 565.
[10]丁中一,贾晋康,王仁.潮汐应力对地震的触发作用[J].地震学报,1983,5(2):172-184.
[11]杜品仁.潮汐与地震关系初探[J].地震科学研究,1981,(1):14-20.
[12]高锡铭,殷志山,王威中,等.固体潮应力张量对地震的触发作用[J].地震学报,1981,3(3):264-275.
[13]冯向东,魏东平.地震活动性与日月引潮力相关性统计分析[J].国际地震动态,2007,(5):9-15.
[14]韩延本,李志安,田静.日、月引潮力变化与某些地区地震发生时间的相关研究[J].地球物理学进展,1996,11(2):114-122.
[15]张晶,郗钦文,杨林章,等.引潮力与潮汐应力对强震触发的研究[J].地球物理学报,2007,50(2):448-454.
[16]赵娟,韩延本,李志安.日月引潮力与华北地区的地震[J].地球物理学报,1999,42(增):24-29.
[17]Dix C H.Triggering of some earthquakes[J].Proc Japan Acad,XL,1964,(6):410-415.
[18]Heaton T H.Tidal triggering of earthquakes[J].Bull Seism Soc Amer,1982,72(6):1 811-2 200.
[19]Knopoff L.Earth tides as a triggering mechanism for earthquakes[J].Bull Seism Soc Amer,1964,54:1 865-1 870.
[20]Tsuruoka H,Masakazu O,Haruo S.Statistical test of the tidal triggering of earthquakes;contribu-tion of the ocean tide loading effect[J].Geophys J Int,1995,1:183-194.
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