由现今小震资料研究琼北地区区域应力场和发震构造
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摘要
利用2000年以来海南地震台网记录的琼北地区的波形资料,采用双差法对103个地震进行重新定位,采用振幅比方法测定震源机制.在此基础上,反演了琼北地区的区域应力场,由震源位置拟合出两个震源断层面,并且计算在区域应力场作用下的滑动方式.对照历史大震的等震线,WNW走向的震源断层位于极震区中部稍偏东的地方,与等震线长轴方向相同,表明该震源断层是1605年琼山大震的发震构造;高倾角震源断层的北东盘向东南斜下方滑动,对于该盘NNW象限产生强烈拉张,以致出现罕见的陆陷成海现象.另外一条NS向震源断层恰好位于第四系火山岩和第四系盆地交界处,是区域升降运动最为强烈的地方,正断层类型的震源断层东盘下降,与沉积盆地一致.研究表明由现今小震反演的两条震源断层分别与历史大震及构造运动有关,而与浅表断裂并不重合,存在深浅构造不协调的现象.
Based on the seismic waveforms recorded by Hainan seismic network in the northern Hainan island since 2000,103 arthquakes were relocated by double-difference method and some focal mechanisms were determined by amplitude ratio.We inverted the regional stress field from the focal mechanism and two focal fault planes from the precise hypocenters,and inferred the slip type of the focal fault under the regional stress field.Contrasting with the isoseismal line of the historical earthquake,the WNW focal fault located in the eastern central part of the meizoseismal area,which has the same direction as the major axis of the meizoseismal area.This indicates the focal fault may be the seismogenic structure of Qiongshan earthquake in 1605.The northeast wall of the high angle focal fault slipped down to southeast,which makes the NNW quadrant extensional and leads to the land subsidence into the sea.Another NS focal fault just located on the boundary between the Quaternaryvolcanic rocks and Quaternary basin where the lifting movement is the most intense.The eastern wall of the normal focal fault dropped,which was consistent with the sedimentary basin.The results show that this two focal faults are related to the historical earthquake and tectonic movement,but do not coincide with the surface fault,indicating an uncoordinated phenomenon between the shallow and deep tectonics.
Based on the seismic waveforms recorded by Hainan seismic network in the northern Hainan island since 2000,103 arthquakes were relocated by double-difference method and some focal mechanisms were determined by amplitude ratio.We inverted the regional stress field from the focal mechanism and two focal fault planes from the precise hypocenters,and inferred the slip type of the focal fault under the regional stress field.Contrasting with the isoseismal line of the historical earthquake,the WNW focal fault located in the eastern central part of the meizoseismal area,which has the same direction as the major axis of the meizoseismal area.This indicates the focal fault may be the seismogenic structure of Qiongshan earthquake in 1605.The northeast wall of the high angle focal fault slipped down to southeast,which makes the NNW quadrant extensional and leads to the land subsidence into the sea.Another NS focal fault just located on the boundary between the Quaternaryvolcanic rocks and Quaternary basin where the lifting movement is the most intense.The eastern wall of the normal focal fault dropped,which was consistent with the sedimentary basin.The results show that this two focal faults are related to the historical earthquake and tectonic movement,but do not coincide with the surface fault,indicating an uncoordinated phenomenon between the shallow and deep tectonics.
引文
陈恩民,黄咏茵.1989.1605年海南岛琼州大地震的震害特征和发震构造研究[J].地震学报,11(3):319--331.
刁桂苓,于利民,李钦祖.1994.强震前后震源区应力场变化一例[J].地震学报,16(1):64--69.
刁桂苓,张四昌,蔡华昌,张跃刚.2004.张北震区附近形变的成因:与王超、张红等人商榷[J].科学通报,49(12):1214--1216.
刁桂苓,张四昌,赵军,王兆军,王俊国.1999.用现今小地震研究历史强震的震源断层:以1830年河北磁县7.5级地震为例[J].地震地质,21(2):121--126.
海南省海洋地震与工程地震研究所.2003.海口市奥林匹克花园地震安全性评价报告[R].海口:海南省海洋工程地震研究所.
嘉世旭,李志雄,徐朝繁,沈繁銮,赵文俊,杨卓欣,杨建,雷宛.2006.雷琼拗陷地壳结构特征[J].地球物理学报,49(5):1385--1394.
姜效典,李巍然.1994.海南岛潜在震源区的研究[J].自然灾害学报,3(1):104--109.
李坪,杨美娥,刘行松,赵翔.1988.琼北地区活动性断裂带的研究[G]∥丁原章,李坪,时振梁,林纪曾,朱振宇编.海南岛北部地震研究文集.北京:地震出版社:41--52.
李志雄,雷建设,赵大鹏,武巴特尔,沈繁銮,丘学林.2008.海南岛及邻区地壳三维P波速度结构[J].地震学报,30(5):441--448.
李建生.1991.海南岛地区断裂构造体系与区域稳定性[J].海洋科学,75(3):19--21.
李钦祖.1974.一个研究小地震机制的方法[J].地球物理学报,17(3):155--164.
林纪曾,梁国昭,赵毅.1980.东南沿海地区的震源机制与构造应力场[J].地震学报,2(3):245--257.
刘辉,洪汉净,冉洪流,沈繁銮,赵波,陈会仙.2008.琼北火山群形成的动力学机制及地震现象的新认识[J].地球物理学报,51(6):1804--1809.
梁尚鸿,李幼铭,束沛镒.1984.利用区域地震台网P、S振幅比资料测定小震震源参数[J].地球物理学报,27(3):247--257.
万永革,沈正康,刁桂苓,王福昌,胡新亮,盛书中.2008.利用小震分布和区域应力方向确定大震断层面参数方法研究及其在唐山地震序列中的应用[J].地球物理学报,51(3):793--804.
汪一鹏.1988.干冲—木棠断裂带的初步研究[G]∥丁原章,李坪,时振梁,林纪曾,朱振宇编.海南岛北部地震研究文集.北京:地震出版社:53--61.
中国地震局震害防御司.1995.中国历史强震目录:公元前23世纪—公元1911年[M].北京:地震出版社:529.
中国地震局地壳应力研究所.2005a.乐东22-1/15-1气田场址、路由地震危险性分析报告[R].北京:中国地震局地壳应力研究所.
中国地震局地壳应力研究所.2005b.涠洲11-1/6-1/11-4N油田开发工程场址地震危险性分析报告[R].北京:中国地震局地壳应力研究所.
张仲英,刘瑞华.1989.海南岛第四系火山岩的分期[J].地质科学,1(1):67--76.
Chiu J M,Johnston A C,Yang Y T.1992.Imaging of fault zone geometry in the central New Madrid seismic zone using data collected by PANDA[J].Seism Res Lett,63:375--393.
Geiger L.1912.Herdeatimming bei erdbeben aus den ankunftszeiten[J].K Ges Wiss Gott,4:331--349.
Himes L,Stauder W,Herrmann R B.1988.Indication of active faults in the New Madrid seismic zone from precise location of hypocenters[J].Seism Res Lett,59(4):123--131.
Johnston A C.1993.Seismic source scaling in eastern North America and the size of the 1811New Madrid and 1886Charleston earthquakes[J].Eos,Trans Amer Geophys Un,74(16):281.
Lebedev S,Chevrot S,Nolet G,Van der Hilst R.2000.New seismic evidence for a deep mantle origin of the S.China basalts(the Hainan plume?)and other observations in SE Asia[J].Eos,Trans Amer Geophys Un,81:48--148.
Lei J S,Zhao D P,Steinberger B.2009.New seismic constraints on the upper mantle structure of the Hainan plume,Phys[J].Earth Planet Inter,173(1--2):33--50.
Spence W.1980.Relative epicenter determination using P-wave arrival-time differences[J].Bull Seism Soc Amer,70(1):171--183.
Waldhauser F,Ellsworth W L.2000.A double-difference earthquake location algorithm:Method and application to the Northern Hayward fault,California[J].Bull Seism Soc Amer,90(6):1353--1368.
刁桂苓,于利民,李钦祖.1994.强震前后震源区应力场变化一例[J].地震学报,16(1):64--69.
刁桂苓,张四昌,蔡华昌,张跃刚.2004.张北震区附近形变的成因:与王超、张红等人商榷[J].科学通报,49(12):1214--1216.
刁桂苓,张四昌,赵军,王兆军,王俊国.1999.用现今小地震研究历史强震的震源断层:以1830年河北磁县7.5级地震为例[J].地震地质,21(2):121--126.
海南省海洋地震与工程地震研究所.2003.海口市奥林匹克花园地震安全性评价报告[R].海口:海南省海洋工程地震研究所.
嘉世旭,李志雄,徐朝繁,沈繁銮,赵文俊,杨卓欣,杨建,雷宛.2006.雷琼拗陷地壳结构特征[J].地球物理学报,49(5):1385--1394.
姜效典,李巍然.1994.海南岛潜在震源区的研究[J].自然灾害学报,3(1):104--109.
李坪,杨美娥,刘行松,赵翔.1988.琼北地区活动性断裂带的研究[G]∥丁原章,李坪,时振梁,林纪曾,朱振宇编.海南岛北部地震研究文集.北京:地震出版社:41--52.
李志雄,雷建设,赵大鹏,武巴特尔,沈繁銮,丘学林.2008.海南岛及邻区地壳三维P波速度结构[J].地震学报,30(5):441--448.
李建生.1991.海南岛地区断裂构造体系与区域稳定性[J].海洋科学,75(3):19--21.
李钦祖.1974.一个研究小地震机制的方法[J].地球物理学报,17(3):155--164.
林纪曾,梁国昭,赵毅.1980.东南沿海地区的震源机制与构造应力场[J].地震学报,2(3):245--257.
刘辉,洪汉净,冉洪流,沈繁銮,赵波,陈会仙.2008.琼北火山群形成的动力学机制及地震现象的新认识[J].地球物理学报,51(6):1804--1809.
梁尚鸿,李幼铭,束沛镒.1984.利用区域地震台网P、S振幅比资料测定小震震源参数[J].地球物理学报,27(3):247--257.
万永革,沈正康,刁桂苓,王福昌,胡新亮,盛书中.2008.利用小震分布和区域应力方向确定大震断层面参数方法研究及其在唐山地震序列中的应用[J].地球物理学报,51(3):793--804.
汪一鹏.1988.干冲—木棠断裂带的初步研究[G]∥丁原章,李坪,时振梁,林纪曾,朱振宇编.海南岛北部地震研究文集.北京:地震出版社:53--61.
中国地震局震害防御司.1995.中国历史强震目录:公元前23世纪—公元1911年[M].北京:地震出版社:529.
中国地震局地壳应力研究所.2005a.乐东22-1/15-1气田场址、路由地震危险性分析报告[R].北京:中国地震局地壳应力研究所.
中国地震局地壳应力研究所.2005b.涠洲11-1/6-1/11-4N油田开发工程场址地震危险性分析报告[R].北京:中国地震局地壳应力研究所.
张仲英,刘瑞华.1989.海南岛第四系火山岩的分期[J].地质科学,1(1):67--76.
Chiu J M,Johnston A C,Yang Y T.1992.Imaging of fault zone geometry in the central New Madrid seismic zone using data collected by PANDA[J].Seism Res Lett,63:375--393.
Geiger L.1912.Herdeatimming bei erdbeben aus den ankunftszeiten[J].K Ges Wiss Gott,4:331--349.
Himes L,Stauder W,Herrmann R B.1988.Indication of active faults in the New Madrid seismic zone from precise location of hypocenters[J].Seism Res Lett,59(4):123--131.
Johnston A C.1993.Seismic source scaling in eastern North America and the size of the 1811New Madrid and 1886Charleston earthquakes[J].Eos,Trans Amer Geophys Un,74(16):281.
Lebedev S,Chevrot S,Nolet G,Van der Hilst R.2000.New seismic evidence for a deep mantle origin of the S.China basalts(the Hainan plume?)and other observations in SE Asia[J].Eos,Trans Amer Geophys Un,81:48--148.
Lei J S,Zhao D P,Steinberger B.2009.New seismic constraints on the upper mantle structure of the Hainan plume,Phys[J].Earth Planet Inter,173(1--2):33--50.
Spence W.1980.Relative epicenter determination using P-wave arrival-time differences[J].Bull Seism Soc Amer,70(1):171--183.
Waldhauser F,Ellsworth W L.2000.A double-difference earthquake location algorithm:Method and application to the Northern Hayward fault,California[J].Bull Seism Soc Amer,90(6):1353--1368.
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