伽师强震群区上地壳三维速度层析成像——人工爆破和天然地震的联合反演
|
摘要
伽师震区位于天山褶皱、帕米尔构造弧与塔里木块体三个构造单元的交接地带,近年来该区发生了一系列的强震活动.为进一步获得该震区详细的地壳速度结构,本文利用人工爆破和天然地震资料联合反演的方法,对1997年新疆伽师震区布设的三维人工地震透射台阵和流动地震台网的资料进行处理,重建了台阵下方上地壳三维速度扰动图像,并结合地震活动分布,对伽师强震群的地震成因作出进一步分析.结果表明研究区上地壳速度结构在纵向和横向上具有明显的非均匀性,随着深度的逐渐加深,震区下方以萨如锡为中心的低速异常体逐步被高速异常体所替代.自12 km深度开始,在与强震群震中相应的位置上,明显出现沿北北西向的高P波速度异常体,在其周围为相对低速分布,呈现出低速条带环绕高速条带的分布格局,VP/VS在相同的位置上也表现为高值分布.这种结构上的差异可能与伽师强震群发生有密切关系.16 km深度的P波速度层析图表明,伽师强震群发生在地壳相对高速扰动区内或是高速扰动向低速扰动过渡的边缘,壳内高速体的存在为强震的孕育和发生提供了重要基础.
Jiashi strong earthquake swarm region is located at the juncture area of three tectonic units,i.e.Tianshan fold zone,Pamir tectonic arc and Tarim block.Many strong earthquakes occurred recently in this area.In order to obtain the fine crustal velocity structures of this area,the data from a 3-D seismic transmission experiment and a portable seismograph network acquired in Jiashi strong earthquake swarm region in 1997 are processed.Joint inversion of explosion and earthquake data is carried out to reconstruct the 3-D images of velocity perturbation of the upper crust under the seismic arrary.The temporaty seismic array was used to record the seismic waves generated by 8 shots fired at different azimaths,and the additional 20 seismic stations were deployed in this area to record local earthquakes.The results show that the structures of the upper crust in the study area is characterized by obvious inhomogeneouities both laterally and vertically.The low P wave velocity zone centered at Saruxi beneath the Jiashi earthquake swarm area is gradually replaced by high P wave velocities with the increase of depth.There is a high P wave velocity anomaly striking NNW at the depth of 12 km under the earthquake swarm area.It extends downwards to the depth of 16 km at least,and is surrounded by relatively low velocities.V_P/V_S ratios are also characterized by high values in this region.This kind of structural differences may be related to the occurrences of Jiashi strong earthquake swarm.It can be found from the P wave velocity images at the depth of 16 km that Jiashi strong earthquake swarm generally occurred in the regions with comparatively high P wave velocity perturbations or in the transition zones between high and low velocity perturbations.The existence of high P wave velocity anomaly in the crust may play an important role in the seismogenic process.
Jiashi strong earthquake swarm region is located at the juncture area of three tectonic units,i.e.Tianshan fold zone,Pamir tectonic arc and Tarim block.Many strong earthquakes occurred recently in this area.In order to obtain the fine crustal velocity structures of this area,the data from a 3-D seismic transmission experiment and a portable seismograph network acquired in Jiashi strong earthquake swarm region in 1997 are processed.Joint inversion of explosion and earthquake data is carried out to reconstruct the 3-D images of velocity perturbation of the upper crust under the seismic arrary.The temporaty seismic array was used to record the seismic waves generated by 8 shots fired at different azimaths,and the additional 20 seismic stations were deployed in this area to record local earthquakes.The results show that the structures of the upper crust in the study area is characterized by obvious inhomogeneouities both laterally and vertically.The low P wave velocity zone centered at Saruxi beneath the Jiashi earthquake swarm area is gradually replaced by high P wave velocities with the increase of depth.There is a high P wave velocity anomaly striking NNW at the depth of 12 km under the earthquake swarm area.It extends downwards to the depth of 16 km at least,and is surrounded by relatively low velocities.V_P/V_S ratios are also characterized by high values in this region.This kind of structural differences may be related to the occurrences of Jiashi strong earthquake swarm.It can be found from the P wave velocity images at the depth of 16 km that Jiashi strong earthquake swarm generally occurred in the regions with comparatively high P wave velocity perturbations or in the transition zones between high and low velocity perturbations.The existence of high P wave velocity anomaly in the crust may play an important role in the seismogenic process.
引文
[1]滕吉文,王谦身,王光杰等.喜马拉雅“东构造结”地区的特异重力场与深部地壳结构.地球物理学报,2006,49(4):1045~1052Teng J W,Wang Q S,Wang G J,et al.Specific gravity field anddeep crustal structure of the Himalayas east structural knot.ChineseJ.Geophys.(in Chinese),2006,49(4):1045~1052
[2]张云峰,王海涛,徐锡伟等.2003年2月24日新疆巴楚—伽师6.8级地震.国际地震动态,2003,291:1~10Wang Y F,Wang H T,Xu X W,et al.The earthquake ofM6.8occurring in Bachu-Jiashi region,Xinjiang Uygur Autonomous Regionon February 24,2003.Recent Development in World Seismology(inChinese),2003,291:1~10
[3]杨欣,高国英.1997年伽师强震群序列特征和震源机制的初步研究.地震学报,1998,20(6):573~579Yang X,Gao G Y.A preliminary researth on the characteristics andthe source mechanism of the Jiashi strong earthquake swarm.ActaSeismologica Sinica(in Chinese),1998,20(6):573~579
[4]朱令仁,苏乃秦,杨马陵.1997年新疆伽师强震群及三次成功的临震预报.中国地震,1998,14(2):101~115Zhu L R,Su N Q,Yang M L.Activety of the 1997 Jiashi strongswarm in Xinjiang and three successful prediction for it.EarthquakeResearth in China(in Chinese),1998,14(2):101~115
[5]周仕勇.1997年伽师强震群研究及其生成机理的探索[博士论文].北京:中国地震局地球物理所,1999Zhou X Y.Researth on source parameters and seismogenesis of theJiashi strong earthquake swarm in 1997[Ph.D.thesis](inChinese).Beijing:Geophysical Institute,China EarthquakeAdministration,1999
[6]刘启元,陈九辉,李顺成等.新疆伽师强震群区三维地壳上地幔S波速度结构及其地震成因的探讨.地球物理学报,2000,43(3):356~365Liu Q Y,Chen J H,Li S C,et al.Passive seismic experiment inXinjiang-Jiashi strong earthquake region and discussion on its seismicgenesis.Chinese J.Geophys.(in Chinese),2000,43(3):356~365
[7]张先康,赵金仁,张成科等.帕米尔东北侧地壳结构研究.地球物理学报,2002,45(5):665~671Zhang X K,Zhao J R,Zhang C K,et al.Crustal structure at theNortheast side of the Pamirs.Chinese J.Geophys.(in Chinese),2002,45(5):665~671
[8]胥颐,刘建华,刘福田等.天山—帕米尔结合带的地壳速度结构及地震活动研究.地球物理学报,2006,49(2):469~476Xu Y,Liu J H,Liu F T,et al.Crustal velocity structure and seismicactivity in the Tianshan-Pamir conjunctive zone.Chinese J.Geophys.(in Chinese),2006,49(2):469~476
[9]周仕勇,许忠淮,韩京等.主地震定位法分析以及1997年新疆伽师强震群高精度定位.地震学报,1999,21(3):258~265Zhou S Y,Xu Z H,Han J,et al.Precise location of the 1997 Jiashistrong earthquake swarm and its tectonic implication.ActaSeismologica Sinica(in Chinese),1999,21(3):258~265
[10]杨卓欣,赵金仁,张先康等.伽师强震群区上地壳三维速度层析成像.地震学报,2002,24(2):153~161Yang Z X,Zhao J R,Zhang X K,et al.Tomographic determination ofthe upper crustal structure in Jiashi strong earthquake swarm region.Acta Seismologica Sinica(in Chinese),2002,24(2):153~161
[11]曲国胜,陈杰,陈新发等.塔里木盆地阿图什—八盘水磨反冲构造系统研究.地震地质,2001,23(1):1~14Qu G S,Chen J,Chen X F,et al.A study of the back-thrustingsystem at Atushi-Bapanshuimo in Tarin basin.Seismology andGeology,2001,23(1):1~14
[12]樊计昌,李松林,赖晓铃等.新疆伽师地震区三维Q值结构.地震学报,2001,23(6):573~581Fan J C,Li S L,Lai X L,et al.Three-dimentionalQstructure inJiashi earthquake region of Xinjiang region.Acta Seismologica Sinica(in Chinese),2001,23(6):573~581
[13]潘素珍,张先康,杨卓欣等.利用反演方法确定新疆伽师地震的定位.地震地质,2004,26(1):153~160Pan S Z,Zhang X K,Yang Z X,et al.Precise location of Jiashi,Xinjiang earthquake by using inversion method.Seismology andGeology(in Chinese),2004,26(1):153~160
[14]张先康,杨卓欣,杨玉春等.地壳三维结构的层析成像方法—爆炸和地震资料的联合反演.地震学报,1995,17(4):422~Zhang X K,Yang Z X,Yang Y C,et al.Method of tomographicdetermination of the 3-D crustal structure—Joint inversion ofexplosion and earthquake data.Acta Seismologica Sinica(inChinese),1995,17(4):422~431
[15]Nercession A,Hirn A,Tarantola A.Three-dimensional seismictransmission prospecting of Mont Dore Volcano.Geophys.J.R.astr.Soc,1984,76:307~315
[16]Tarantola A.Inverse Problem Theory,Methods for Data Fitting andModel Parameter Estimation.Elsevier Science Publ.Co,1986.506~528
[17]Tarantola A,Nercession A.Three-demensional inversion withoutblocks.Geophys.J.R.astr.Soc,1984,76:299~306
[18]徐朝繁,张先康,段永红等.新疆伽师强震群区上部地壳细结构的高分辨折射地震探测研究.地震学报,2006,28(1):60~69Xu Z F,Zhang X K,Duan Y H,et al.Fine upper crustal structure ofJiashi strong earthquake swarm region in Xinjiang inferred from highresolution seismic refraction profile data.Acta Seismologica Sinica(in Chinese),2006,28(1):60~69
[19]胥颐,刘福田,刘建华等.天山地震带的地壳结构与强震构造环境.地球物理学报,2000,43(2):184~193Xu Y,Liu F T,Liu J H,et al.Crustal structure and background ofstrong seismic conformation in Tianshan earthquake region.ChineseJ.Geophys.(in Chinese),2000,43(2):184~193
[20]刘志,张先康,周雪松等.帕米尔东北侧地壳物性结构及其发震环境探讨.地震学报,2003,25(3):242~249Liu Z,Zhang X K,Zhou X S,et al.Study of crustal structure in termsof physical property and discussion on seismogenic environment in thenortheastern Pamirs.Acta Seismologica Sinica(in Chinese),2003,25(3):242~249
[21]梅世蓉.地震前兆场物理模式与前兆时空分布机制研究(一)—坚固体孕震模式的由来与证据.地震学报,1995,17(3):273~282Mei S R.On the physical model of earthquake precursor fields andthe mechanism of precursor time-space distribution:Origin andevidence of the strong body earthquake-genm,erating model.ActaSeismologica Sinica(in Chinese),1995,17(3):273~282
[2]张云峰,王海涛,徐锡伟等.2003年2月24日新疆巴楚—伽师6.8级地震.国际地震动态,2003,291:1~10Wang Y F,Wang H T,Xu X W,et al.The earthquake ofM6.8occurring in Bachu-Jiashi region,Xinjiang Uygur Autonomous Regionon February 24,2003.Recent Development in World Seismology(inChinese),2003,291:1~10
[3]杨欣,高国英.1997年伽师强震群序列特征和震源机制的初步研究.地震学报,1998,20(6):573~579Yang X,Gao G Y.A preliminary researth on the characteristics andthe source mechanism of the Jiashi strong earthquake swarm.ActaSeismologica Sinica(in Chinese),1998,20(6):573~579
[4]朱令仁,苏乃秦,杨马陵.1997年新疆伽师强震群及三次成功的临震预报.中国地震,1998,14(2):101~115Zhu L R,Su N Q,Yang M L.Activety of the 1997 Jiashi strongswarm in Xinjiang and three successful prediction for it.EarthquakeResearth in China(in Chinese),1998,14(2):101~115
[5]周仕勇.1997年伽师强震群研究及其生成机理的探索[博士论文].北京:中国地震局地球物理所,1999Zhou X Y.Researth on source parameters and seismogenesis of theJiashi strong earthquake swarm in 1997[Ph.D.thesis](inChinese).Beijing:Geophysical Institute,China EarthquakeAdministration,1999
[6]刘启元,陈九辉,李顺成等.新疆伽师强震群区三维地壳上地幔S波速度结构及其地震成因的探讨.地球物理学报,2000,43(3):356~365Liu Q Y,Chen J H,Li S C,et al.Passive seismic experiment inXinjiang-Jiashi strong earthquake region and discussion on its seismicgenesis.Chinese J.Geophys.(in Chinese),2000,43(3):356~365
[7]张先康,赵金仁,张成科等.帕米尔东北侧地壳结构研究.地球物理学报,2002,45(5):665~671Zhang X K,Zhao J R,Zhang C K,et al.Crustal structure at theNortheast side of the Pamirs.Chinese J.Geophys.(in Chinese),2002,45(5):665~671
[8]胥颐,刘建华,刘福田等.天山—帕米尔结合带的地壳速度结构及地震活动研究.地球物理学报,2006,49(2):469~476Xu Y,Liu J H,Liu F T,et al.Crustal velocity structure and seismicactivity in the Tianshan-Pamir conjunctive zone.Chinese J.Geophys.(in Chinese),2006,49(2):469~476
[9]周仕勇,许忠淮,韩京等.主地震定位法分析以及1997年新疆伽师强震群高精度定位.地震学报,1999,21(3):258~265Zhou S Y,Xu Z H,Han J,et al.Precise location of the 1997 Jiashistrong earthquake swarm and its tectonic implication.ActaSeismologica Sinica(in Chinese),1999,21(3):258~265
[10]杨卓欣,赵金仁,张先康等.伽师强震群区上地壳三维速度层析成像.地震学报,2002,24(2):153~161Yang Z X,Zhao J R,Zhang X K,et al.Tomographic determination ofthe upper crustal structure in Jiashi strong earthquake swarm region.Acta Seismologica Sinica(in Chinese),2002,24(2):153~161
[11]曲国胜,陈杰,陈新发等.塔里木盆地阿图什—八盘水磨反冲构造系统研究.地震地质,2001,23(1):1~14Qu G S,Chen J,Chen X F,et al.A study of the back-thrustingsystem at Atushi-Bapanshuimo in Tarin basin.Seismology andGeology,2001,23(1):1~14
[12]樊计昌,李松林,赖晓铃等.新疆伽师地震区三维Q值结构.地震学报,2001,23(6):573~581Fan J C,Li S L,Lai X L,et al.Three-dimentionalQstructure inJiashi earthquake region of Xinjiang region.Acta Seismologica Sinica(in Chinese),2001,23(6):573~581
[13]潘素珍,张先康,杨卓欣等.利用反演方法确定新疆伽师地震的定位.地震地质,2004,26(1):153~160Pan S Z,Zhang X K,Yang Z X,et al.Precise location of Jiashi,Xinjiang earthquake by using inversion method.Seismology andGeology(in Chinese),2004,26(1):153~160
[14]张先康,杨卓欣,杨玉春等.地壳三维结构的层析成像方法—爆炸和地震资料的联合反演.地震学报,1995,17(4):422~Zhang X K,Yang Z X,Yang Y C,et al.Method of tomographicdetermination of the 3-D crustal structure—Joint inversion ofexplosion and earthquake data.Acta Seismologica Sinica(inChinese),1995,17(4):422~431
[15]Nercession A,Hirn A,Tarantola A.Three-dimensional seismictransmission prospecting of Mont Dore Volcano.Geophys.J.R.astr.Soc,1984,76:307~315
[16]Tarantola A.Inverse Problem Theory,Methods for Data Fitting andModel Parameter Estimation.Elsevier Science Publ.Co,1986.506~528
[17]Tarantola A,Nercession A.Three-demensional inversion withoutblocks.Geophys.J.R.astr.Soc,1984,76:299~306
[18]徐朝繁,张先康,段永红等.新疆伽师强震群区上部地壳细结构的高分辨折射地震探测研究.地震学报,2006,28(1):60~69Xu Z F,Zhang X K,Duan Y H,et al.Fine upper crustal structure ofJiashi strong earthquake swarm region in Xinjiang inferred from highresolution seismic refraction profile data.Acta Seismologica Sinica(in Chinese),2006,28(1):60~69
[19]胥颐,刘福田,刘建华等.天山地震带的地壳结构与强震构造环境.地球物理学报,2000,43(2):184~193Xu Y,Liu F T,Liu J H,et al.Crustal structure and background ofstrong seismic conformation in Tianshan earthquake region.ChineseJ.Geophys.(in Chinese),2000,43(2):184~193
[20]刘志,张先康,周雪松等.帕米尔东北侧地壳物性结构及其发震环境探讨.地震学报,2003,25(3):242~249Liu Z,Zhang X K,Zhou X S,et al.Study of crustal structure in termsof physical property and discussion on seismogenic environment in thenortheastern Pamirs.Acta Seismologica Sinica(in Chinese),2003,25(3):242~249
[21]梅世蓉.地震前兆场物理模式与前兆时空分布机制研究(一)—坚固体孕震模式的由来与证据.地震学报,1995,17(3):273~282Mei S R.On the physical model of earthquake precursor fields andthe mechanism of precursor time-space distribution:Origin andevidence of the strong body earthquake-genm,erating model.ActaSeismologica Sinica(in Chinese),1995,17(3):273~282
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心