利用长期GPS观测资料分析昆仑断裂现今滑动速率与地壳活动特性
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摘要
利用昆仑断裂区域的GPS观测资料,通过高精度数据处理获取区域地壳运动速度场,进而通过速度剖面线估算昆仑断裂现今形变速率。结果表明,昆仑断裂在94°E、101°E、103°E附近的现今滑动速率分别为12.8±1.9 mm/a、6.1±0.9 mm/a、0.7±2.1 mm/a。进一步分析得到如下结论:1)本文估算的昆仑断裂10 a尺度的现今滑动速率和万年尺度的地质学结果基本一致,说明现今滑动速率可以作为断裂地震风险性评估的有效输入数据;2)昆仑断裂东段具有向东逐渐减小的滑动速率,减少的速率可能主要被阿尼玛卿山的地壳增厚和断裂东段的顺时针旋转所吸收;3)昆仑断裂的西大滩-东大滩地震空区位于高应变区。
In order to study the present-day slip rate and crustal activity characteristic of the Kunlun fault, this paper derives a regional GPS velocity field from GPS observations in the Kunlun fault region using high-precision data-processing strategy, and it then estimates present-day deformation rates of the Kunlun fault based on GPS velocity profiles. The result indicates that present-day slip rates of the Kunlun fault near 94°E, 101°E and 103°E are 12.8±1.9 mm/a, 6.1±0.9 mm/a and 0.7±2.1 mm/a, respectively. Further study and analysis show the following conclusions:(1) The present-day slip rates on the 10-year timescale along the Kunlun fault estimated by this paper are consistent with the geological results on the 10~4 years timescale, implying that the present-day slip rates can be a useful input data set for the seismic hazard assessment;(2) The eastern Kunlun fault has an eastward-decreasing slip rate. We argue that the crustal thickening across Anyemaqen mountains and the clockwise rotation of the eastern Kunlun fault accommodate most of the decrease;(3) The Xidatan-Dongdatan seismic gap in the Kunlun fault lies in the high-strain region.
In order to study the present-day slip rate and crustal activity characteristic of the Kunlun fault, this paper derives a regional GPS velocity field from GPS observations in the Kunlun fault region using high-precision data-processing strategy, and it then estimates present-day deformation rates of the Kunlun fault based on GPS velocity profiles. The result indicates that present-day slip rates of the Kunlun fault near 94°E, 101°E and 103°E are 12.8±1.9 mm/a, 6.1±0.9 mm/a and 0.7±2.1 mm/a, respectively. Further study and analysis show the following conclusions:(1) The present-day slip rates on the 10-year timescale along the Kunlun fault estimated by this paper are consistent with the geological results on the 10~4 years timescale, implying that the present-day slip rates can be a useful input data set for the seismic hazard assessment;(2) The eastern Kunlun fault has an eastward-decreasing slip rate. We argue that the crustal thickening across Anyemaqen mountains and the clockwise rotation of the eastern Kunlun fault accommodate most of the decrease;(3) The Xidatan-Dongdatan seismic gap in the Kunlun fault lies in the high-strain region.
引文
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[13] Harkins N,Kirby E,Shi X,et al.Millennial Slip Rates along the Eastern Kunlun Fault:Implications for the Dynamics of Intracontinental Deformation in Asia[J].Lithosphere,2010,2(4):247-266
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[19] Ren J J,Xu X W,Yeats R S,et al.Millennial Slip Rates of the Tazang Fault,the Eastern Termination of Kunlun Fault:Implications for Strain Partitioning in Eastern Tibet[J].Tectonophysics,2013,608:1 180-1 200
[20] England P,Molnar P.Late Quaternary to Decadal Velocity Fields in Asia[J].Journal of Geophysical Research:Solid Earth,2005,110(B12)
[21] Bird P,Kreemer C,Holt W E.A Long-Term Forecast of Shallow Seismicity Based on the Global Strain Rate Map[J].Seismological Research Letters,2010,81(2):184-194
[22] Lin A,Guo J.Nonuniform Slip Rate and Millennial Recurrence Interval of Large Earthquakes along the Eastern Segment of the Kunlun Fault,Northern Tibet[J].Bulletin of the Seismological Society of America,2008,98(6):2 866-2 878
[23] Loveless J P,Meade B J.Partitioning of Localized and Diffuse Deformation in the Tibetan Plateaufrom Joint Inversions of Geologic and Geodetic Observations[J].Earth and Planetary Science Letters,2011,303(1-2):11-24
[24] Yuan D Y,Champagnac J D,Ge W P,et al.Late Quaternary Right-Lateral Slip Rates of Faults Adjacent to the Lake Qinghai,Northeastern Margin of the Tibetan Plateau[J].Geological Society of America Bulletin,2011,123(9-10):2 016-2 030
[25] Kirby E,Harkins N.Distributed Deformation around the Eastern Tip of the Kunlun Fault[J].International Journal of Earth Sciences,2013,102(7):1 759-1 772
[26] Wang H,Wright T J.Satellite Geodetic Imaging Reveals Internal Deformation of Western Tibet[J].Geophysical Research Letters,2012,39(7):L07303
[27] Xiong X,Shan B,Zheng Y,et al.Stress Transfer and Its Implication for Earthquake Hazard on the Kunlun Fault,Tibet[J].Tectonophysics,2010,482(1-4):216-225
[2] Wang Q,Zhang P Z,Freymueller J T,et al.Present-Day Crustal Deformation in China Constrained by Global Positioning System Measurements[J].Science,2001,294(5 542):574-577
[3] Zhang P Z,Shen Z K,Wang M,et al.Continuous Deformation of the Tibetan Plateau from Global Positioning System Data[J].Geology,2004,32(9):809-812
[4] Garthwaite M C,Wang H,Wright T J.Broadscale Interseismic Deformation and Fault Slip Rates in the Central Tibetan Plateau Observed Using InSAR[J].Journal of Geophysical Research:Solid Earth,2013,118(9):5 071-5 083
[5] 施闯,赵齐乐,楼益栋,等.卫星导航系统综合分析处理软件PANDA及研究进展[J].航天器工程,2009,18(4):64-70(Shi Chuang,Zhao Qile,Lou Yidong,et al.PANDA:Comprehensive Processing Software for Satellite Navigation Systems and Its Research Progress[J].Spacecraft Engineering,2009,18(4):64-70)
[6] 甘卫军,张锐,张勇,等.中国地壳运动观测网络的建设及应用[J].国际地震动态,2007(7):43-52(Gan Weijun,Zhang Rui,Zhang Yong,et al.Development of the Crustal Movement Observation Network in China and Its Applications[J].Recent Developments in World Seismology,2007(7):43-52)
[7] Kreemer C,Blewitt G,Klein E C.A Geodetic Plate Motion and Global Strain Rate Model[J].Geochemistry,Geophysics,Geosystems,2014,15(10):3 849-3 889
[8] Ryder I,Bürgmann R,Pollitz F.Low Crustal Relaxation beneath the Tibetan Plateau and Qaidam Basin Following the 2001 Kokoxili Earthquake[J].Geophysical Journal International,2011,187(2):613-630
[9] Duvall A R,Clark M K.Dissipation of Fast Strike-Slip Faulting Within and Beyond Northeastern Tibet[J].Geology,2010,38(3):223-226
[10] Woerd J V D,Tapponnier P,Ryerson F J,et al.Uniform Postglacial Slip-Rate along the Central 600 km of the Kunlun Fault(Tibet),from 26Al,10Be,and 14C Dating of Riser Offsets,and Climatic Origin of the Regional Morphology[J].Geophysical Journal International,2002,148(3):356-388
[11] Brown E T,Bendick R,Bourlès D L,et al.Slip Rates of the Karakorum Fault,Ladakh,India,Determined Using Cosmic Ray Exposure Dating of Debris Flows and Moraines[J].Journal of Geophysical Research:Solid Earth,2002,107(B9):2 192
[12] Hetzel R,Niedermann S,Tao M X,et al.Low Slip Rates and Long-Term Preservation of Geomorphic Features in Central Asia[J].Nature,2002,417(6 887):428-432
[13] Harkins N,Kirby E,Shi X,et al.Millennial Slip Rates along the Eastern Kunlun Fault:Implications for the Dynamics of Intracontinental Deformation in Asia[J].Lithosphere,2010,2(4):247-266
[14] Kidd W S F,Molnar P.Quaternary and Active Faulting Observed on the 1985 Academia Sinica-Royal Society Geotraverse of Tibet[J].Philosophical Transactions of the Royal Society of London A:Mathematical and Physical Sciences,1988,327(1 594):337-363
[15] Li H B,Woerd J V D,Tapponnier P,et al.Slip Rate on the Kunlun Fault at Hongshui Gou,and Recurrence Time of Great Events Comparable to the 14/11/2001,MW～7.9 Kokoxili Earthquake[J].Earth and Planetary Science Letters,2005,237(1-2):285-299
[16] Gold R D,Cowgill E.Deriving Fault-Slip Histories to Test for Secular Variation in Slip,with Examples from the Kunlun and Awatere Faults[J].Earth and Planetary Science Letters,2011,301(1-2):52-64
[17] Kirby E,Harkins N,Wang E Q,et al.Slip Rate Gradients along the Eastern Kunlun Fault[J].Tectonics,2007,26(2):TC2010
[18] Harkins N,Kirby E.Fluvial Terrace Riser Degradation and Determination of Slip Rates on Strike-Slip Faults:An Example from the Kunlun Fault,China[J].Geophysical Research Letters,2008,35(5):L05406
[19] Ren J J,Xu X W,Yeats R S,et al.Millennial Slip Rates of the Tazang Fault,the Eastern Termination of Kunlun Fault:Implications for Strain Partitioning in Eastern Tibet[J].Tectonophysics,2013,608:1 180-1 200
[20] England P,Molnar P.Late Quaternary to Decadal Velocity Fields in Asia[J].Journal of Geophysical Research:Solid Earth,2005,110(B12)
[21] Bird P,Kreemer C,Holt W E.A Long-Term Forecast of Shallow Seismicity Based on the Global Strain Rate Map[J].Seismological Research Letters,2010,81(2):184-194
[22] Lin A,Guo J.Nonuniform Slip Rate and Millennial Recurrence Interval of Large Earthquakes along the Eastern Segment of the Kunlun Fault,Northern Tibet[J].Bulletin of the Seismological Society of America,2008,98(6):2 866-2 878
[23] Loveless J P,Meade B J.Partitioning of Localized and Diffuse Deformation in the Tibetan Plateaufrom Joint Inversions of Geologic and Geodetic Observations[J].Earth and Planetary Science Letters,2011,303(1-2):11-24
[24] Yuan D Y,Champagnac J D,Ge W P,et al.Late Quaternary Right-Lateral Slip Rates of Faults Adjacent to the Lake Qinghai,Northeastern Margin of the Tibetan Plateau[J].Geological Society of America Bulletin,2011,123(9-10):2 016-2 030
[25] Kirby E,Harkins N.Distributed Deformation around the Eastern Tip of the Kunlun Fault[J].International Journal of Earth Sciences,2013,102(7):1 759-1 772
[26] Wang H,Wright T J.Satellite Geodetic Imaging Reveals Internal Deformation of Western Tibet[J].Geophysical Research Letters,2012,39(7):L07303
[27] Xiong X,Shan B,Zheng Y,et al.Stress Transfer and Its Implication for Earthquake Hazard on the Kunlun Fault,Tibet[J].Tectonophysics,2010,482(1-4):216-225