2016年1月21日门源M_S 6.4级地震InSAR同震形变及发震构造研究
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摘要
2016年1月21日青海省门源县发生M_S 6.4级地震,距离震中位置最近的已知断裂为位于其北侧7 km的冷龙岭断裂,该断裂晚第四纪以来主要表现为左旋走滑运动,局部兼具倾滑分量.但本次地震的震源机制解显示为逆冲型地震,与人们认知的冷龙岭断裂走滑运动性质有所差异.本研究利用Sentinel-1A数据获取了升降轨方向的形变场,形变场特征显示本次地震以逆冲为主,最大形变量在6 cm左右.以此数据为约束,采用两步法反演了发震断层参数,结果显示仅以InSAR数据为约束并不能唯一确定断层的倾向,因此本文对比了NE倾向和SW倾向等不同断层模型的反演结果,综合分析该地区的地质构造背景,认为SW倾向的断层模型更加合理,本次地震由冷龙岭北侧的弧形次生断层引起,发震断层面走向141°,倾向SW,倾角43°,平均滑动角为72.7°,最大滑动量为0.44 m,反演矩震级为M_W 6.0,震源深度10 km.该次生断层与冷龙岭断裂一起构成正花状构造,冷龙岭主干断层近直立插入基底,夹持部分形成隆起断块,推测本次地震是青藏高原向NW推挤生长,在压扭性作用下隆起断块的一种表现.
On January 21 st, 2016, an M_S 6.4 earthquake hit Menyuan County, Qinghai province, China. The nearest known fault to the earthquake is the Lenglongling fault which is located approximately 7 km north of the epicenter. This fault has mainly shown sinistral strike-slip movement since the late Quaternary Period, with a localized dip-slip component. However, the focal mechanism indicates that it is a thrust earthquake, which is different from the well-known strike-slip feature of the Lenglongling fault. In this study, we obtained the ascending and descending orbit coseismic deformation field of the Menyuan earthquake using the Sentinel-1 A data. The characteristics of the deformation field indicate that this earthquake was a thrust-type earthquake, with a maximum Line-of-Sight(LOS)deformation of around 6 cm. Constrained by these InSAR data, based on the Okada Model we invert the fault distribution and source parameters through constructing fault model of different dip direction. The inversion results show that the seismic fault plane has a strike, dip direction and dip angle of approximately 141°, NE and 43°, respectively. The maximum slip distance is 0.44 m, and the average slip angle is 72.7°, with a magnitude of M_W 6.0 and focal depth of 10 km. By considering the geological structure of the seismogenic zone and the inversion results, we suggest that this earthquake was caused by the arc-shaped subfault located at the north side of the Lenglongling fault. This subfault, together with the Lenglongling fault, forms a normal flower structure. Therefore, we infer that this earthquake is the manifestation of a neotectonic movement, in which the bulging fault block is lifted further up under the compresso-shear action caused by the Tibetan Plateau pushing towards the northwest direction.
On January 21 st, 2016, an M_S 6.4 earthquake hit Menyuan County, Qinghai province, China. The nearest known fault to the earthquake is the Lenglongling fault which is located approximately 7 km north of the epicenter. This fault has mainly shown sinistral strike-slip movement since the late Quaternary Period, with a localized dip-slip component. However, the focal mechanism indicates that it is a thrust earthquake, which is different from the well-known strike-slip feature of the Lenglongling fault. In this study, we obtained the ascending and descending orbit coseismic deformation field of the Menyuan earthquake using the Sentinel-1 A data. The characteristics of the deformation field indicate that this earthquake was a thrust-type earthquake, with a maximum Line-of-Sight(LOS)deformation of around 6 cm. Constrained by these InSAR data, based on the Okada Model we invert the fault distribution and source parameters through constructing fault model of different dip direction. The inversion results show that the seismic fault plane has a strike, dip direction and dip angle of approximately 141°, NE and 43°, respectively. The maximum slip distance is 0.44 m, and the average slip angle is 72.7°, with a magnitude of M_W 6.0 and focal depth of 10 km. By considering the geological structure of the seismogenic zone and the inversion results, we suggest that this earthquake was caused by the arc-shaped subfault located at the north side of the Lenglongling fault. This subfault, together with the Lenglongling fault, forms a normal flower structure. Therefore, we infer that this earthquake is the manifestation of a neotectonic movement, in which the bulging fault block is lifted further up under the compresso-shear action caused by the Tibetan Plateau pushing towards the northwest direction.
引文
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Dong Z P,Cheng J W,Zhang B,et al.2016.An overview of the 21 Jan 2016 MS 6.4 Menyuan earthquake sequences in Qinghai Province [J].Recent Developments in World Seismology (in Chinese).2016(10):4-10.
Funning G J,Parsons B,Wright T J,et al.2005.Surface displacements and source parameters of the 2003 Bam (Iran)earthquake from Envisat advanced synthetic aperture radar imagery [J].Journal of Geophysical Research:Solid Earth,110(B9).
Gabriel A,Goldstein R,Zebker H.1989.Mapping Small Elevation Changes Over Large Areas:Differential Radar Interferometry [J].Journal of Geophysical Research:Solid Earth,94(B7):9183-9191.
Gaudemer Y,Tapponnier P,Meyer B,et al.1995.Partitioning of crustal slip between linked,active faults in the eastern Qilian Shan,and evidence for a major seismic gap,the ‘Tianzhu gap’,on the western Haiyuan Fault,Gansu (China)[J].Geophysical Journal International,120(3):599- 645.
Guo P,Han Z J,An Y F,et al.2017.Activity of the Lenglongling fault system and seismotectonics of the 2016 MS 6.4 Menyuan earthquake [J].Science China Earth Sciences (Ser D),60(5):929-942.
Hanssen R F.2001.Radar Interferometry:Data Interpretation and Error Analysis [M].Remote Sensing and Digital Image Processing (Vol.2).United States of America:Kluwer Academic Publishers.https://doi.org/10.1017/CBO9781107415324.004.
He W G,Liu B C,Yuan D Y,et al.2000.Research on slip rates of the Lenglongling active fault zone [J].Northwestern Seismological Journal (in Chinese),22(1):90-97.
He W G,Yuan D Y,Ge W P,et al.2010.Determination of the slip rate of the Lenglongling fault in the middle and eastern segments of the Qilian Mountain active fault zone [J].Earthquake (in Chinese),30(1):131-137.
Institute Of Geology And Lanzhou Institute Of Seismology,S.S.B.1993.The Active Fault System in Qilian Mountain-Hexi Corridor [M].Beijing:Seismological Press (in Chinese).
Institute Of Geology,S S B.1990.Haiyuan Active Fault Zone [M].Beijing:Seismological Press (in Chinese).
Jónsson S,Zebker H,Segall P,et al.2002.Fault Slip Distribution of the 1999 MW 7.1 Hector Mine,California,Earthquake,Estimated from Satellite Radar and GPS Measurements [J].Bulletin of the Seismological Society of America,92(4):1377-1389.
Lasserre C,Gaudemer Y,Tapponnier P,et al.2002.Fast late Pleistocene slip rate on the Leng Long Ling segment of the Haiyuan fault,Qinghai,China [J].Journal of Geophysical Research:Solid Earth,107(B11):ETG 4-1-ETG 4-15.
Liang S M,Gan W J,Shen C,et al.2013.Three-dimensional velocity field of present-day crustal motion of the Tibetan Plateau derived from GPS measurements [J].Journal of Geophysical Research:Solid Earth,118(10):5722-5732.
Liu X F,Xiao L Z,Mei X P,et al.2005.Characteristics of seismicity and sequence patterns in Qilianshan seismic belt [J].Northwestern Seismological Journal (in Chinese),27(01):56- 60.
Massonnet D,Rossi M,Carmona C,et al.1993.The displacement field of the Landers earthquake mapped by radar interferometry [J].Nature,364(6433):138-142.
Okada Y.1985.Surface deformation due to shear and tensile faults in a half-space [J].Bulletin of the Seismological Society of America,75(4):1135-1154.
Parsons B,Wright T,Rowe P,et al.2006.The 1994 Sefidabeh (eastern Iran)earthquakes revisited:new evidence from satellite radar interferometry and carbonate dating about the growth of an active fold above a blind thrust fault [J].Geophysical Journal International,164(1):202-217,doi:10.1111/j.1365-246X.2005.02655.x.
Waldhauser F,Ellsworth W L.2000.A double-difference earthquake location algorithm:method and application to the northern hayward fault,california [J].Bulletin of the Seismological Society of America,90(6):1353-1368.
Wang C S,Ding X L,Shan X J et al.2012.Slip distribution of the 2011 Tohoku earthquake derived from joint inversion of GPS,InSAR and seafloor GPS/acoustic measurements [J].Journal of Asian Earth Sciences,57(6):128-136.
Wang L,Wang R.F.Roth,et al.2009.Afterslip and Viscoelastic Relaxation Following the 1999 M 7.4 Izmit Earthquake from GPS Measurements [J].Geophysical Journal International,178(3):1220-1237.
Wang Q,Zhang P Z,Niu Z,et al.2002.Present-day crustal movement and tectonic deformation in China continent [J].Science in China Series D:Earth Sciences,45(10):865-874.
Wang R J,Diao F Q,Hoechner A.2013.SDM - A geodetic inversion code incorporating with layered crust structure and curved fault geometry[C].EGU General Assembly Conference Abstracts,2013.
Wells D,Coppersmith K.1994.New empirical relationships among magnitude,rupture length,rupture width,rupture area,and surface displacement [J].Bulletin of the Seismological Society of America,84(4):974-1002.
Werner C,Wegmller U,Strozzi T,et al.2000.GAMMA SAR and interferometric processing software[C].Proc.ERS-Envisat Symposium,Gothenburg.
Wright T J,Parsons B E,Jackson J A,et al.1999.Source parameters of the 1 October 1995 Dinar (Turkey)earthquake from SAR interferometry and seismic bodywave modelling [J].Earth and Planetary Science Letters,172(1-2):23-37.
Xu J R,Yao L X,Wang J.1986.Earthquake source mechanisms of Menyuan earthquake (ms=6.4,on Aug.26,1986)and its strong aftershocks [J].Northwestern Seismological Journal (in Chinese),8(4):84-86.
Zheng W J,He W G,Zhao G K,et al.2005.Discussion on the Causative Structure and Mechanism of the 2003 Minle-Shandan,Gansu,M 6.1,5.8 Earthquakes [J].Journal Of Seismological Research (in Chinese),28(2):133-140.
Zheng W J,Zhang P Z,He W G,et al.2013.Transformation of displacement between strike-slip and crustal shortening in the northern margin of the Tibetan Plateau:Evidence from decadal GPS measurements and late Quaternary slip rates on faults[J].Tectonophysics,584(1):267-280.
国家地震局地质研究所.1990.海原活动断裂带[M].北京:地震出版社.
国家地震局地质研究所,国家地震局兰州地震研究所.1993.祁连山-河西走廊活动断裂系[M].北京:地震出版社.
何文贵,袁道阳,葛伟鹏,等.2010.祁连山活动断裂带中东段冷龙岭断裂滑动速率的精确厘定[J].地震,30(1):131-137.
何文贵,刘百篪,袁道阳,等.2000.冷龙岭活动断裂的滑动速率研究[J].地震工程学报,22(1):90-97.
刘小凤,肖丽珠,梅秀萍,等.2005.祁连山地震带地震活动特征及序列类型[J].西北地震学报,27(1):56- 60.
徐纪人,姚立珣,汪进.1986.1986年8月26日门源6.4级地震及其强余震的震源机制解[J].西北地震学报,(4):84-86.
郑文俊,何文贵,赵广坤,等.2005.2003年甘肃民乐—山丹6.1,5.8级地震发震构造及发震机制探讨[J].地震研究,28(2):133-140.
Dong Z P,Cheng J W,Zhang B,et al.2016.An overview of the 21 Jan 2016 MS 6.4 Menyuan earthquake sequences in Qinghai Province [J].Recent Developments in World Seismology (in Chinese).2016(10):4-10.
Funning G J,Parsons B,Wright T J,et al.2005.Surface displacements and source parameters of the 2003 Bam (Iran)earthquake from Envisat advanced synthetic aperture radar imagery [J].Journal of Geophysical Research:Solid Earth,110(B9).
Gabriel A,Goldstein R,Zebker H.1989.Mapping Small Elevation Changes Over Large Areas:Differential Radar Interferometry [J].Journal of Geophysical Research:Solid Earth,94(B7):9183-9191.
Gaudemer Y,Tapponnier P,Meyer B,et al.1995.Partitioning of crustal slip between linked,active faults in the eastern Qilian Shan,and evidence for a major seismic gap,the ‘Tianzhu gap’,on the western Haiyuan Fault,Gansu (China)[J].Geophysical Journal International,120(3):599- 645.
Guo P,Han Z J,An Y F,et al.2017.Activity of the Lenglongling fault system and seismotectonics of the 2016 MS 6.4 Menyuan earthquake [J].Science China Earth Sciences (Ser D),60(5):929-942.
Hanssen R F.2001.Radar Interferometry:Data Interpretation and Error Analysis [M].Remote Sensing and Digital Image Processing (Vol.2).United States of America:Kluwer Academic Publishers.https://doi.org/10.1017/CBO9781107415324.004.
He W G,Liu B C,Yuan D Y,et al.2000.Research on slip rates of the Lenglongling active fault zone [J].Northwestern Seismological Journal (in Chinese),22(1):90-97.
He W G,Yuan D Y,Ge W P,et al.2010.Determination of the slip rate of the Lenglongling fault in the middle and eastern segments of the Qilian Mountain active fault zone [J].Earthquake (in Chinese),30(1):131-137.
Institute Of Geology And Lanzhou Institute Of Seismology,S.S.B.1993.The Active Fault System in Qilian Mountain-Hexi Corridor [M].Beijing:Seismological Press (in Chinese).
Institute Of Geology,S S B.1990.Haiyuan Active Fault Zone [M].Beijing:Seismological Press (in Chinese).
Jónsson S,Zebker H,Segall P,et al.2002.Fault Slip Distribution of the 1999 MW 7.1 Hector Mine,California,Earthquake,Estimated from Satellite Radar and GPS Measurements [J].Bulletin of the Seismological Society of America,92(4):1377-1389.
Lasserre C,Gaudemer Y,Tapponnier P,et al.2002.Fast late Pleistocene slip rate on the Leng Long Ling segment of the Haiyuan fault,Qinghai,China [J].Journal of Geophysical Research:Solid Earth,107(B11):ETG 4-1-ETG 4-15.
Liang S M,Gan W J,Shen C,et al.2013.Three-dimensional velocity field of present-day crustal motion of the Tibetan Plateau derived from GPS measurements [J].Journal of Geophysical Research:Solid Earth,118(10):5722-5732.
Liu X F,Xiao L Z,Mei X P,et al.2005.Characteristics of seismicity and sequence patterns in Qilianshan seismic belt [J].Northwestern Seismological Journal (in Chinese),27(01):56- 60.
Massonnet D,Rossi M,Carmona C,et al.1993.The displacement field of the Landers earthquake mapped by radar interferometry [J].Nature,364(6433):138-142.
Okada Y.1985.Surface deformation due to shear and tensile faults in a half-space [J].Bulletin of the Seismological Society of America,75(4):1135-1154.
Parsons B,Wright T,Rowe P,et al.2006.The 1994 Sefidabeh (eastern Iran)earthquakes revisited:new evidence from satellite radar interferometry and carbonate dating about the growth of an active fold above a blind thrust fault [J].Geophysical Journal International,164(1):202-217,doi:10.1111/j.1365-246X.2005.02655.x.
Waldhauser F,Ellsworth W L.2000.A double-difference earthquake location algorithm:method and application to the northern hayward fault,california [J].Bulletin of the Seismological Society of America,90(6):1353-1368.
Wang C S,Ding X L,Shan X J et al.2012.Slip distribution of the 2011 Tohoku earthquake derived from joint inversion of GPS,InSAR and seafloor GPS/acoustic measurements [J].Journal of Asian Earth Sciences,57(6):128-136.
Wang L,Wang R.F.Roth,et al.2009.Afterslip and Viscoelastic Relaxation Following the 1999 M 7.4 Izmit Earthquake from GPS Measurements [J].Geophysical Journal International,178(3):1220-1237.
Wang Q,Zhang P Z,Niu Z,et al.2002.Present-day crustal movement and tectonic deformation in China continent [J].Science in China Series D:Earth Sciences,45(10):865-874.
Wang R J,Diao F Q,Hoechner A.2013.SDM - A geodetic inversion code incorporating with layered crust structure and curved fault geometry[C].EGU General Assembly Conference Abstracts,2013.
Wells D,Coppersmith K.1994.New empirical relationships among magnitude,rupture length,rupture width,rupture area,and surface displacement [J].Bulletin of the Seismological Society of America,84(4):974-1002.
Werner C,Wegmller U,Strozzi T,et al.2000.GAMMA SAR and interferometric processing software[C].Proc.ERS-Envisat Symposium,Gothenburg.
Wright T J,Parsons B E,Jackson J A,et al.1999.Source parameters of the 1 October 1995 Dinar (Turkey)earthquake from SAR interferometry and seismic bodywave modelling [J].Earth and Planetary Science Letters,172(1-2):23-37.
Xu J R,Yao L X,Wang J.1986.Earthquake source mechanisms of Menyuan earthquake (ms=6.4,on Aug.26,1986)and its strong aftershocks [J].Northwestern Seismological Journal (in Chinese),8(4):84-86.
Zheng W J,He W G,Zhao G K,et al.2005.Discussion on the Causative Structure and Mechanism of the 2003 Minle-Shandan,Gansu,M 6.1,5.8 Earthquakes [J].Journal Of Seismological Research (in Chinese),28(2):133-140.
Zheng W J,Zhang P Z,He W G,et al.2013.Transformation of displacement between strike-slip and crustal shortening in the northern margin of the Tibetan Plateau:Evidence from decadal GPS measurements and late Quaternary slip rates on faults[J].Tectonophysics,584(1):267-280.
国家地震局地质研究所.1990.海原活动断裂带[M].北京:地震出版社.
国家地震局地质研究所,国家地震局兰州地震研究所.1993.祁连山-河西走廊活动断裂系[M].北京:地震出版社.
何文贵,袁道阳,葛伟鹏,等.2010.祁连山活动断裂带中东段冷龙岭断裂滑动速率的精确厘定[J].地震,30(1):131-137.
何文贵,刘百篪,袁道阳,等.2000.冷龙岭活动断裂的滑动速率研究[J].地震工程学报,22(1):90-97.
刘小凤,肖丽珠,梅秀萍,等.2005.祁连山地震带地震活动特征及序列类型[J].西北地震学报,27(1):56- 60.
徐纪人,姚立珣,汪进.1986.1986年8月26日门源6.4级地震及其强余震的震源机制解[J].西北地震学报,(4):84-86.
郑文俊,何文贵,赵广坤,等.2005.2003年甘肃民乐—山丹6.1,5.8级地震发震构造及发震机制探讨[J].地震研究,28(2):133-140.