拉萨地区及其周边的地震活动性研究
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摘要
印度和欧亚陆-陆板块碰撞造就的青藏高原地震活动十分频繁.但由于地理因素限制,青藏高原内部地震台站分布稀疏,因此全球地震台网很难监测青藏高原内部发生的小型地震活动.本文通过对北京大学布设的流动台阵自2007年1月至2008年3月地震记录的分析,精确定位了拉萨周边地区的79个区域小震,发现了两个可能是受到岩浆或地下水活动影响而形成的震群,以及拉萨附近一条近期比较活跃的断层,并给出了全球台网对于该地区地震定位误差的估计.
The continental collision of the Indian and Eurasia plates has created the Tibetan plateau which is also a zone of active earthquakes.Because of the high elevation,there are fewer seismic stations in Tibet and therefore,most of the (small) local earthquakes were not detected by the global seismic network.Here we report our analyses of the earthquake records for the period of January 2007 to March 2008 from a Peking University s portable seismic array.We have relocated 79 local earthquakes in the study area.Among these events,there are two clusters that could be the resulted of either magma migration or the presence of water.The data have shown that a small but active fault exists near the city of Lhasa.We have also estimated the error in the epicenter determination of local earthquakes by the global seismic network.
The continental collision of the Indian and Eurasia plates has created the Tibetan plateau which is also a zone of active earthquakes.Because of the high elevation,there are fewer seismic stations in Tibet and therefore,most of the (small) local earthquakes were not detected by the global seismic network.Here we report our analyses of the earthquake records for the period of January 2007 to March 2008 from a Peking University s portable seismic array.We have relocated 79 local earthquakes in the study area.Among these events,there are two clusters that could be the resulted of either magma migration or the presence of water.The data have shown that a small but active fault exists near the city of Lhasa.We have also estimated the error in the epicenter determination of local earthquakes by the global seismic network.
引文
[1] Molnar P,Chen W.Focal depths and fault plane solutions of earthquakes under the Tibetan plateau.Journal of Geophysical Research,1983,88(B2) :1180-1196
[2] Baranowski J,Armbruster J,Seeber L,et al.Focal depths and fault plane solutions of earthquakes and active tectonics of the Himalaya.Journal of Geophysical Research,1984,89:6918-6928
[3] Zhao W,Nelson K D,Project INDEPTH Team.Deep seismic reflection evidence for continental underthrusting beneath southern Tibet.Nature,1993,366(6455) :557-559
[4] Nelson K D,Zhao W,Brown L D,et al.,Partially molten middle crust beneath southern Tibet:Synthesis of project INDEPTH results.Science,1996,274(5293) :1684
[5] Langin W R,Brown L D,Sandvol E A.Seismicity of central Tibet from Project INDEPTH III seismic recordings.Bulletin of the Seismological Society of America,2003,93(5) :2146-2159
[6] Herquel G,Wittlinger G,Guilbert J.Anisotropy and crustal thickness of Northern-Tibet.New constraints for tectonic modelling.Geophysical Research Letters,1995,22 (14) :1925-1928
[7] Hirn A,Jiang M,Sapin M,et al.Seismic anisotropy as an indicator of mantle flow beneath the Himalayas and Tibet.Nature,1995,375(6532) :571-574
[8] de la Torre T,Sheehan A.Broadband seismic noise analysis of the Himalayan Nepal Tibet seismic experiment.Seismol Soc America.2005,1202-1208
[9] Liang X,Zhou S,Chen Y J,et al.Earthquake distribution in southern Tibet and its tectonic implications.Journal of Geophysical Research-Solid Earth,2008,113(B12) :B12409
[10] Pandey M,Tandukar R,Avouac J,et al.Seismotectonics of the Nepal Himalaya from a local seismic network.Journal of Asian Earth Sciences,1999,17(5-6) :703-712
[11] De R,Kayal J.Seismotectonic model of the Sikkim Himalaya:Constraint from microearthquake surveys. Seismol Soc America,2003,395-1400
[12] Drukpa D,Velasco A,Doser D.Seismicity in the Kingdom of Bhutan (1937 003) :Evidence for crustal transcurrent deformation.Journal of Geophysical Research-Solid Earth,2006,111(B6) :B06301
[13] Turkelli N,Sandvol E,Zor E,et al.Seismogenic zones in eastern Turkey.Geophys.Res.Lett,2003,30(24) :8039
[14] Real C R,Teng T L.Local Richter magnitude and total signal duration in southern California.Bulletin of the Seismological Society of America,1973,63(5) :1809-1827
[15] Klein F W.User's Guide to Hypoinverse-2000． a Fortran program to solve for earthquake locations and magnitudes. US Geol.Surv.Open File Rept.,2002． 2-171
[16] Jin G,Chen Y J,Sandvol E,et al.Receiver Function Images of the Crust and Upper Mantle Structure of Southern Tibet. AGU Fall Meeting.2006
[17] Chen Y J,Jin G.Seismic Evidence for the Moho in southern Tibet as a Phase Change Boundary.AGU Fall Meeting.2008
[18] 中国地质调查局,成都地质矿产研究所.青藏高原及邻区地质图.成都:成都地图出版社,2004 Institute of Geology and Mineralogy of Chengdu,Chinese Geological Survey.Geological Map of Tibatan Plateau and Adjacent Regions (in Chinese).Chengdu:Chengdu Map Press,2004
[19] 中国科学院青藏高原综合科学考察队,西藏地热.北京:科学出版社.附图一.1981 Science Team of Multidisciplinary Field Research of Tibatan Plateau,Chinese Academy of Science.The Geoheat of Tibet.Supplementary Map One (in Chinese).Beijing:Science Press,1981
[20] Brown L D,Zhao W,Nelson K D,et al.Bright spots,structure,and magmatism in southern Tibet from INDEPTH seismic reflection profiling.Science,1996,274(5293) :1688
[21] Sohn R A,Crawford W C,Webb S C.Local seismicity following the 1998 eruption of Axial Volcano.Geophysical Research Letters,1999,26(23) :3433-3436
[22] Guo Y-H,Chen Y J.Dynamic triggering of local earthquakes by 2004 M_w9． 0 Sumatra Earthquake.WPGM,T22A-05,24-27,July 2006
[23] Husen S,Wiemer S,Smith R.Remotely triggered seismicity in the Yellowstone National Park region by the 2002 M_w7． 9 Denali fault earthquake,Alaska.Bulletin of the Seismological Society of America,2004,94(6B):317-331
[2] Baranowski J,Armbruster J,Seeber L,et al.Focal depths and fault plane solutions of earthquakes and active tectonics of the Himalaya.Journal of Geophysical Research,1984,89:6918-6928
[3] Zhao W,Nelson K D,Project INDEPTH Team.Deep seismic reflection evidence for continental underthrusting beneath southern Tibet.Nature,1993,366(6455) :557-559
[4] Nelson K D,Zhao W,Brown L D,et al.,Partially molten middle crust beneath southern Tibet:Synthesis of project INDEPTH results.Science,1996,274(5293) :1684
[5] Langin W R,Brown L D,Sandvol E A.Seismicity of central Tibet from Project INDEPTH III seismic recordings.Bulletin of the Seismological Society of America,2003,93(5) :2146-2159
[6] Herquel G,Wittlinger G,Guilbert J.Anisotropy and crustal thickness of Northern-Tibet.New constraints for tectonic modelling.Geophysical Research Letters,1995,22 (14) :1925-1928
[7] Hirn A,Jiang M,Sapin M,et al.Seismic anisotropy as an indicator of mantle flow beneath the Himalayas and Tibet.Nature,1995,375(6532) :571-574
[8] de la Torre T,Sheehan A.Broadband seismic noise analysis of the Himalayan Nepal Tibet seismic experiment.Seismol Soc America.2005,1202-1208
[9] Liang X,Zhou S,Chen Y J,et al.Earthquake distribution in southern Tibet and its tectonic implications.Journal of Geophysical Research-Solid Earth,2008,113(B12) :B12409
[10] Pandey M,Tandukar R,Avouac J,et al.Seismotectonics of the Nepal Himalaya from a local seismic network.Journal of Asian Earth Sciences,1999,17(5-6) :703-712
[11] De R,Kayal J.Seismotectonic model of the Sikkim Himalaya:Constraint from microearthquake surveys. Seismol Soc America,2003,395-1400
[12] Drukpa D,Velasco A,Doser D.Seismicity in the Kingdom of Bhutan (1937 003) :Evidence for crustal transcurrent deformation.Journal of Geophysical Research-Solid Earth,2006,111(B6) :B06301
[13] Turkelli N,Sandvol E,Zor E,et al.Seismogenic zones in eastern Turkey.Geophys.Res.Lett,2003,30(24) :8039
[14] Real C R,Teng T L.Local Richter magnitude and total signal duration in southern California.Bulletin of the Seismological Society of America,1973,63(5) :1809-1827
[15] Klein F W.User's Guide to Hypoinverse-2000． a Fortran program to solve for earthquake locations and magnitudes. US Geol.Surv.Open File Rept.,2002． 2-171
[16] Jin G,Chen Y J,Sandvol E,et al.Receiver Function Images of the Crust and Upper Mantle Structure of Southern Tibet. AGU Fall Meeting.2006
[17] Chen Y J,Jin G.Seismic Evidence for the Moho in southern Tibet as a Phase Change Boundary.AGU Fall Meeting.2008
[18] 中国地质调查局,成都地质矿产研究所.青藏高原及邻区地质图.成都:成都地图出版社,2004 Institute of Geology and Mineralogy of Chengdu,Chinese Geological Survey.Geological Map of Tibatan Plateau and Adjacent Regions (in Chinese).Chengdu:Chengdu Map Press,2004
[19] 中国科学院青藏高原综合科学考察队,西藏地热.北京:科学出版社.附图一.1981 Science Team of Multidisciplinary Field Research of Tibatan Plateau,Chinese Academy of Science.The Geoheat of Tibet.Supplementary Map One (in Chinese).Beijing:Science Press,1981
[20] Brown L D,Zhao W,Nelson K D,et al.Bright spots,structure,and magmatism in southern Tibet from INDEPTH seismic reflection profiling.Science,1996,274(5293) :1688
[21] Sohn R A,Crawford W C,Webb S C.Local seismicity following the 1998 eruption of Axial Volcano.Geophysical Research Letters,1999,26(23) :3433-3436
[22] Guo Y-H,Chen Y J.Dynamic triggering of local earthquakes by 2004 M_w9． 0 Sumatra Earthquake.WPGM,T22A-05,24-27,July 2006
[23] Husen S,Wiemer S,Smith R.Remotely triggered seismicity in the Yellowstone National Park region by the 2002 M_w7． 9 Denali fault earthquake,Alaska.Bulletin of the Seismological Society of America,2004,94(6B):317-331
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