日本熊本M_W7.0地震同震位移场和震源滑动模型反演
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摘要
利用2016年4月16日日本熊本M W7.0地震震中周围94个近场强震动台的观测资料和新近改进的强震经验基线校正方法SMBLOC,尝试解算并绘制了一个内陆M7左右走滑型地震的同震位移场全貌,并反演了其震源滑动模型.与日本国土地理院(GSI)公布的该地震57个GPS同震位移结果的比较显示,两种完全不同资料、不同解算方法给出的水平同震位移场的最大幅值均为100cm左右,均呈右旋走滑为主兼具部分正断分量的震源机制.强震最大水平和垂直永久位移分别为104.5cm和58.0cm,分别出现在震中东北侧的KMMH162台和KMM005台.两种资料单独以及联合反演的震源滑动模型均表明,此次地震为北东侧破裂为主并呈双事件特征,且主要滑动均不在初始破裂点附近,而是集中于第二次事件周围,即距离初始破裂点东北侧约20km处的走向长约40km、倾向宽约20km的范围内.基于强震和GPS模型所得的最大滑动量分别为5.10m和5.87m,量级一致,反演矩震级均为MW7.1左右;主破裂区近地表滑动量比野外调查结果略微偏大,可能与数值效应有关.此外,还利用不同方法得到的解算结果比较了熊本地震特有的12组台间距在3km以内的GPS-强震台站对各自的三分量同震位移,其结果表明对于M7左右的地震而言,SMBLOC方法解算同震位移时方向和幅值的可靠性下限约为2cm.
Near-source coseismic displacement field of the 16 April 2016 MW7.0 Kumamoto,Japan,earthquake is estimated from 94 digital strong motion records after correction for their baseline errors using an improved empirical method SMBLOG,and compared with that from 57 GPS observations published by Geospatial Information Authority of Japan(GSI).Furthermore,three slip models of the earthquake are inverted from the displacement data of the GPS,strong motion and their combination,suggesting the results are in good agreement.The three models all show that the earthquake is dominated by the rightlateral strike-slip mechanism(also a few normal-fault dislocations).The maximum horizontal and vertical coseismic displacements reached 104.5 cm and58.0 cm,and occurred at the stations KMMH162 and KMM005,respectively.The fault slips are mainly distributed around the second event(about 20 km northeastward from epicenter)and in an area of about 40 km along the strike and 20 km along the dip.The moment magnitude is estimated to be M W7.1,and the peak slip is about 5.10 mfor strong motion data and 5.87 mfor GPS.The surface rupture should be obvious.Moreover,the comparison of the threecomponent coseismic displacements derived from 12 GPS-strong motion stationpairs with interval less than 3 km also indicates that the lower limit is about2 cm for earthquakes of magnitude about 7 when SMBLOC method is used.
Near-source coseismic displacement field of the 16 April 2016 MW7.0 Kumamoto,Japan,earthquake is estimated from 94 digital strong motion records after correction for their baseline errors using an improved empirical method SMBLOG,and compared with that from 57 GPS observations published by Geospatial Information Authority of Japan(GSI).Furthermore,three slip models of the earthquake are inverted from the displacement data of the GPS,strong motion and their combination,suggesting the results are in good agreement.The three models all show that the earthquake is dominated by the rightlateral strike-slip mechanism(also a few normal-fault dislocations).The maximum horizontal and vertical coseismic displacements reached 104.5 cm and58.0 cm,and occurred at the stations KMMH162 and KMM005,respectively.The fault slips are mainly distributed around the second event(about 20 km northeastward from epicenter)and in an area of about 40 km along the strike and 20 km along the dip.The moment magnitude is estimated to be M W7.1,and the peak slip is about 5.10 mfor strong motion data and 5.87 mfor GPS.The surface rupture should be obvious.Moreover,the comparison of the threecomponent coseismic displacements derived from 12 GPS-strong motion stationpairs with interval less than 3 km also indicates that the lower limit is about2 cm for earthquakes of magnitude about 7 when SMBLOC method is used.
引文
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屠泓为,汪荣江,刁法启,张勇,万永革,金明培.2016.运用SDM方法研究2001年昆仑山口西MS8.1地震破裂分布:GPS和InSAR联合反演的结果[J].地球物理学报,59(6):2103--2112.doi:10.6038/cjg20160616.Tu H W,Wang R J,Diao F Q,Zhang Y,Wan Y G,Jin M P.2016.Slip model of the 2001Kunlun mountain MS8.1earthquake by SDM:Joint inversion from GPS and InSAR data[J].Chinese Journal of Geophysics,59(6):2103--2112.doi:10.6038/cjg20160616(in Chinese).
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Asano K,Iwata T.2016.Source rupture processes of the foreshock and mainshock in the 2016Kumamoto earthquake sequence estimated from the kinematic waveform inversion of strong motion data[J].Earth Planet Space,68(1):147.
Boore D M.2001.Effect of baseline corrections on displacement and response spectra for several recordings of the 1999Chi-Chi,Taiwan,earthquake[J].Bull Seismol Soc Am,91(5):1199--1211.
Boore D M,Bommer J J.2005.Processing of strong-motion accelerograms:Needs,options and consequences[J].Soil Dyn Earthq Eng,25(2):93--115.
Chao W A,Wu Y M,Zhao L.2010.An automatic scheme for baseline correction of strong-motion records in coseismic deformation determination[J].J Seismol,14(3):495--504.
Diao F Q,Xiong X,Wang R J.2011.Mechanisms of transient postseismic deformation following the 2001 M W7.8Kunlun(China)earthquake[J].Pure Appl Geophys,168(5):767--779.
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Graizer V M.2010.Strong motion recordings and residual displacements:What are we actually recording in strong motion seismology?[J].Seismol Res Lett,81(4):635--639.
Iwan W D,Moser M A,Peng C Y.1985.Some observations on strong-motion earthquake measurement using a digital acceleration[J].Bull Seismol Soc Am,75(5):1225--1246.
Kinoshita S.1998.Kyoshin net(K-NET)[J].Seismol Res Lett,69(4):309--332.
Kubo H,Suzuki W,Aoi S,Sekiguchi H.2016.Source rupture processes of the 2016Kumamoto,Japan,earthquakes estimated from strong-motion waveforms[J].Earth Planet Space,68(1):161.
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McComb H E,Ruge A C,Neumann F.1943.The determination of true ground motion by integration of strong-motion records:A symposium[J].Bull Seismol Soc Am,33(1):1.
Moya L,Yamazaki F,Liu W.2016.Comparison of coseismic displacement obtained from GEONET and seismic networks[J].J Earthquake Tsunami,10(2):1640002.
Nishimura T,Munekane H,Yarai H.2011.The 2011off the Pacific coast of Tohoku earthquake and its aftershocks observed by GEONET[J].Earth Planet Space,63(7):631--636.
Sagiya T.2004.A decade of GEONET:1994--2003The continuous GPS observation in Japan and its impact on earthquake studies[J].Earth Planet Space,56(8):29--41.
Shirahama Y,Yoshimi M,Awata Y,Maruyama T,Azuma T,Miyashita Y,Mori H,Imanishi K,Takeda N,Ochi T,Otsubo M,Asahina D,Miyakawa A.2016.Characteristics of the surface ruptures associated with the 2016Kumamoto earthquake sequence,central Kyushu,Japan[J].Earth Planet Space,68(1):191.
Trifunac M D 1971.Zero baseline correction of strong-motion accelerograms[J].Bull Seismol Soc Am,61(5):1201--1211.
USGS.2016.M7.0-1km E of Kumamoto-shi,Japan[EB/OL].[2016-06-27].https:∥earthquake.usgs.gov/earthquakes/eventpage/us20005iis#moment-tensor.
Wang G Q,Boore D M,Igel H,Zhou X Y.2003.Some observations on colocated and closely spaced strong groundmotion records of the 1999Chi-Chi,Taiwan,earthquake[J].Bull Seismol Soc Am,93(2):674--693.
Wang G Q,Boore D M,Tang G,Zhou X.2007.Comparisons of ground motions from colocated and closely spaced onesample-per-second global positioning system and accelerograph recordings of the 2003 M6.5San Simeon,California,earthquake in the Parkfield region[J].Bull Seismol Soc Am,97(1B):76--90.
Wang R J,Schurr B,Milkereit C,Shao Z G,Jin M P.2011.An improved automatic scheme for empirical baseline correction of digital strong-motion records[J].Bull Seismol Soc Am,101(5):2029--2044.
Wang R J,Parolai S,Ge M R,Jin M P,Walter T R,Zschau J.2013.The 2011 M W9.0Tohoku earthquake:Comparison of GPS and strong-motion data[J].Bull Seismol Soc Am,103(2B):1336--1347.
Wu Y M,Wu C F.2007.Approximate recovery of coseismic deformation from Taiwan strong-motion records[J].J Seismol,11(2):159--170.
Yagi Y,Okuwaki R,Enescu B,Kasahara A,Miyakawa A,Otsubo M.2016.Rupture process of the 2016Kumamoto earthquake in relation to the thermal structure around Aso volcano[J].Earth Planet Space,68(1):118.
Zhang G H,Qu C Y,Shan X J,Song X G,Zhang G F,Wang C S,Hu J C,Wang R J.2011.Slip distribution of the 2008Wenchuan MS7.9earthquake by joint inversion from GPS and InSAR measurements:A resolution test study[J].Geophys J Int,186(1):207--220.
金明培,汪荣江,屠泓为.2014.芦山7级地震的同震位移估计和震源滑动模型反演尝试[J].地球物理学报,57(1):129--137.doi:10.6038/cjg20140112.Jin M P,Wang R J,Tu H W.2014.Slip model and co-seismic displacement field derived from near-source strong motion records of the Lushan MS7.0earthquake on 20April 2013[J].Chinese Journal of Geophysics,57(1):129--137.doi:10.6038/cjg20140112(in Chinese).
屠泓为,汪荣江,刁法启,张勇,万永革,金明培.2016.运用SDM方法研究2001年昆仑山口西MS8.1地震破裂分布:GPS和InSAR联合反演的结果[J].地球物理学报,59(6):2103--2112.doi:10.6038/cjg20160616.Tu H W,Wang R J,Diao F Q,Zhang Y,Wan Y G,Jin M P.2016.Slip model of the 2001Kunlun mountain MS8.1earthquake by SDM:Joint inversion from GPS and InSAR data[J].Chinese Journal of Geophysics,59(6):2103--2112.doi:10.6038/cjg20160616(in Chinese).
Aoi S.2000.New strong-motion observation network:KiK-net[J].EOS Trans Am Geophys Union,4(3):329.
Aoi S,Kunugi T,Fujiwara H.2004.Strong-motion seismograph network operated by NIED:K-NET and KiK-net[J].JJapan Assoc Earthq Eng,4(3):65--74.
Asano K,Iwata T.2016.Source rupture processes of the foreshock and mainshock in the 2016Kumamoto earthquake sequence estimated from the kinematic waveform inversion of strong motion data[J].Earth Planet Space,68(1):147.
Boore D M.2001.Effect of baseline corrections on displacement and response spectra for several recordings of the 1999Chi-Chi,Taiwan,earthquake[J].Bull Seismol Soc Am,91(5):1199--1211.
Boore D M,Bommer J J.2005.Processing of strong-motion accelerograms:Needs,options and consequences[J].Soil Dyn Earthq Eng,25(2):93--115.
Chao W A,Wu Y M,Zhao L.2010.An automatic scheme for baseline correction of strong-motion records in coseismic deformation determination[J].J Seismol,14(3):495--504.
Diao F Q,Xiong X,Wang R J.2011.Mechanisms of transient postseismic deformation following the 2001 M W7.8Kunlun(China)earthquake[J].Pure Appl Geophys,168(5):767--779.
F-net.2016.Earthquake mechanism information[EB/OL].[2016-04-28].http:∥www.fnet.bosai.go.jp/event/tdmt.php?_id=20160415162400&LANG=en.
Geospatial Information Authority of Japan.2016a.Horizontal crust deformation before and after 16April 2016,Kumamoto,Japan,Mj7.3earthquake[EB/OL].[2016-04-28].http:∥www.gsi.go.jp/common/000193379.jpg(in Japanese).
Geospatial Information Authority of Japan.2016b.Vertical crust deformation before and after 16April 2016,Kumamoto,Japan,Mj7.3earthquake[EB/OL].[2016-04-28].http:∥www.gsi.go.jp/common/000193382.jpg(in Japanese).
Geospatial Information Authority of Japan.2016c.Distribution map(2016-09-12)of continuous GPS stations for 16April2016,Kumamoto,Japan Mj7.3earthquake,renewed on 12September 2016[EB/OL].[2016-04-28].http:∥www.gsi.go.jp/sokuchikijun/H28-kumamoto-earthquake-seika.html(in Japanese).
Geological Survey of Japan,National Institute of Advanced Industrial Science and Technology of Japan.2016.4th report(May 3,2016):Emergency survey report for surface earthquake faults associated with the 2016Kumamoto earthquake[EB/OL].[2016-06-17].https:∥www.gsj.jp/hazards/earthquake/kumamoto2016/kumamoto20160513-1.html(in Japanese).
Graizer V M.1979.Determination of the true ground displacement by using strong motion records[J].Izvestiya Phys Solid Earth,15(12):875--885.
Graizer V M.2005.Effect of tilt on strong motion data processing[J].Soil Dyn Earthq Eng,25(3):197--204.
Graizer V M.2006.Tilts in strong ground motion[J].Bull Seismol Soc Am,96(6):2090--2102.
Graizer V M.2010.Strong motion recordings and residual displacements:What are we actually recording in strong motion seismology?[J].Seismol Res Lett,81(4):635--639.
Iwan W D,Moser M A,Peng C Y.1985.Some observations on strong-motion earthquake measurement using a digital acceleration[J].Bull Seismol Soc Am,75(5):1225--1246.
Kinoshita S.1998.Kyoshin net(K-NET)[J].Seismol Res Lett,69(4):309--332.
Kubo H,Suzuki W,Aoi S,Sekiguchi H.2016.Source rupture processes of the 2016Kumamoto,Japan,earthquakes estimated from strong-motion waveforms[J].Earth Planet Space,68(1):161.
Laske G,Masters G,Ma Z T,Pasyanos M.2013.Update on CRUST1.0:A 1-degree global model of Earth’s crust[J].Geophys Res Abstracts,15:Abstract EGU 2013-2658.
McComb H E,Ruge A C,Neumann F.1943.The determination of true ground motion by integration of strong-motion records:A symposium[J].Bull Seismol Soc Am,33(1):1.
Moya L,Yamazaki F,Liu W.2016.Comparison of coseismic displacement obtained from GEONET and seismic networks[J].J Earthquake Tsunami,10(2):1640002.
Nishimura T,Munekane H,Yarai H.2011.The 2011off the Pacific coast of Tohoku earthquake and its aftershocks observed by GEONET[J].Earth Planet Space,63(7):631--636.
Sagiya T.2004.A decade of GEONET:1994--2003The continuous GPS observation in Japan and its impact on earthquake studies[J].Earth Planet Space,56(8):29--41.
Shirahama Y,Yoshimi M,Awata Y,Maruyama T,Azuma T,Miyashita Y,Mori H,Imanishi K,Takeda N,Ochi T,Otsubo M,Asahina D,Miyakawa A.2016.Characteristics of the surface ruptures associated with the 2016Kumamoto earthquake sequence,central Kyushu,Japan[J].Earth Planet Space,68(1):191.
Trifunac M D 1971.Zero baseline correction of strong-motion accelerograms[J].Bull Seismol Soc Am,61(5):1201--1211.
USGS.2016.M7.0-1km E of Kumamoto-shi,Japan[EB/OL].[2016-06-27].https:∥earthquake.usgs.gov/earthquakes/eventpage/us20005iis#moment-tensor.
Wang G Q,Boore D M,Igel H,Zhou X Y.2003.Some observations on colocated and closely spaced strong groundmotion records of the 1999Chi-Chi,Taiwan,earthquake[J].Bull Seismol Soc Am,93(2):674--693.
Wang G Q,Boore D M,Tang G,Zhou X.2007.Comparisons of ground motions from colocated and closely spaced onesample-per-second global positioning system and accelerograph recordings of the 2003 M6.5San Simeon,California,earthquake in the Parkfield region[J].Bull Seismol Soc Am,97(1B):76--90.
Wang R J,Schurr B,Milkereit C,Shao Z G,Jin M P.2011.An improved automatic scheme for empirical baseline correction of digital strong-motion records[J].Bull Seismol Soc Am,101(5):2029--2044.
Wang R J,Parolai S,Ge M R,Jin M P,Walter T R,Zschau J.2013.The 2011 M W9.0Tohoku earthquake:Comparison of GPS and strong-motion data[J].Bull Seismol Soc Am,103(2B):1336--1347.
Wu Y M,Wu C F.2007.Approximate recovery of coseismic deformation from Taiwan strong-motion records[J].J Seismol,11(2):159--170.
Yagi Y,Okuwaki R,Enescu B,Kasahara A,Miyakawa A,Otsubo M.2016.Rupture process of the 2016Kumamoto earthquake in relation to the thermal structure around Aso volcano[J].Earth Planet Space,68(1):118.
Zhang G H,Qu C Y,Shan X J,Song X G,Zhang G F,Wang C S,Hu J C,Wang R J.2011.Slip distribution of the 2008Wenchuan MS7.9earthquake by joint inversion from GPS and InSAR measurements:A resolution test study[J].Geophys J Int,186(1):207--220.