2017年9月8日墨西哥沿岸M_w8.2级地震海啸观测数据分析与模拟
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摘要
2017年9月8日4时49分(UTC),墨西哥瓦哈卡州沿岸海域(15.21°N,93.64°W)发生M_w8.2级地震,震源深度30 km。强震在该海域引发海啸,海啸对震源附近数百千米范围内造成了严重影响。位于太平洋上的多个海啸监测网络捕捉到了海啸信号并详细记录了此次海啸的传播过程。本文选用了近场2个DART浮标和6个验潮站的水位数据,通过潮汐调和分析和滤波分离出海啸信号,对近场海啸特征值进行了统计分析,并采用小波变换分析方法进一步分析了海啸的波频特征。基于Okada弹性位错理论断层模型计算得到了强震引发的海底形变分布,并采用MOST海啸模式对本次海啸事件近场传播特征进行了模拟,模拟结果与观测吻合较好。最后,基于实测和模拟结果,详细分析了此次地震海啸的近场分布特征,发现除受海啸源的强度和几何分布特征影响外,近岸海啸波还主要受地形特征控制,在与特定地形相互作用后波幅产生放大效应,会进一步加剧海啸造成的灾害。
On September 8, 2017, at 4:49(UTC) a magnitude M_w8.2 earthquake took place off the coast of Oaxaca State, Mexico, focal depth of 30 km. Meanwhile, the earthquake triggered moderate intensity tsunami. The tsunami impacted hundreds of kilometers of the coast of Mexico. Tsunami waves were subsequently recorded by Deep-ocean Assessment and Reporting of Tsunami(DART) buoys in the Pacific Ocean and tide gauges off the coast. In this paper, we apply observational data of 2 DART buoys and 6 tide gauges, and isolate the tsunami waves from boservational data by de-tiding and filtering method, and futher analyze the frequency characteristics of the tsunami waves by wavelet analysis. To compute the co-seismic deformation, we employ the half space elastic theory, and then we analyze the near-field characteristics of this tsunami by numerical simulation with MOST(Method Of Splitting Tsunamis) model. The results based on the observational and simulation data show that, apart from the magnitude and geometric distribution of the earthquake, near-field tsunami waves are mainly controlled by topographic distribution off the coast. Especially, the amplitude of tsunami waves may have amplification effect when interacting with specific topography, which will cause much more damage of the tsunami.
On September 8, 2017, at 4:49(UTC) a magnitude M_w8.2 earthquake took place off the coast of Oaxaca State, Mexico, focal depth of 30 km. Meanwhile, the earthquake triggered moderate intensity tsunami. The tsunami impacted hundreds of kilometers of the coast of Mexico. Tsunami waves were subsequently recorded by Deep-ocean Assessment and Reporting of Tsunami(DART) buoys in the Pacific Ocean and tide gauges off the coast. In this paper, we apply observational data of 2 DART buoys and 6 tide gauges, and isolate the tsunami waves from boservational data by de-tiding and filtering method, and futher analyze the frequency characteristics of the tsunami waves by wavelet analysis. To compute the co-seismic deformation, we employ the half space elastic theory, and then we analyze the near-field characteristics of this tsunami by numerical simulation with MOST(Method Of Splitting Tsunamis) model. The results based on the observational and simulation data show that, apart from the magnitude and geometric distribution of the earthquake, near-field tsunami waves are mainly controlled by topographic distribution off the coast. Especially, the amplitude of tsunami waves may have amplification effect when interacting with specific topography, which will cause much more damage of the tsunami.
引文
[1] 任智源.南海海啸数值模拟研究[D].上海:上海交通大学,2015.Ren Zhiyuan.Numerical simulation of tsunami in South China Sea[D].Shanghai:Shanghai Jiao Tong University,2015.
[2] 任智源,原野,赵联大,等.2016年全球地震海啸监测预警与数值模拟研究[J].海洋科学,2017,41(6):98-110.Ren Zhiyuan,Yuan Ye,Zhao Lianda,et al.Monitoring,early warning and numerical study of global tsunamis in 2016[J].Marine Sciences,2017,41(6):98-110.
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[4] 王培涛,于福江,赵联大,等.2011年3月11日日本地震海啸越洋传播及对中国影响的数值分析[J].地球物理学报,2012,55(9):3088-3096.Wang Peitao,Yu Fujiang,Zhao Lianda,et al.Numerical analysis of tsunami propagating generated by the japan MW9.0 earthquake on Mar.11 in 2011 and its impact on China coasts[J].Chinese Journal of Geophysics,2012,55(9):3088-3096.
[5] 于福江,原野,赵联大,等.2010年2月27日智利8.8级地震海啸对我国影响分析[J].科学通报,2011,56(3):239-246.Yu Fujiang,Yuan Ye,Zhao Lianda,et al.Evaluation of potential hazards from teletsunami in China:Tidal observations of a teletsunami generated by the Chile 8.8 Mw earthquake[J].Chinese Science Bulletin,2011,56(11):1108-1116.
[6] Omira R,Baptista M A,Lisboa F.Tsunami characteristics along the Peru-Chile trench:analysis of the 2015 MW8.3 Illapel,the 2014 MW8.2 Iquique and the 2010 MW8.8 Maule Tsunamis in the Near-field[J].Pure and Applied Geophysics,2016,173(4):1063-1077.
[7] 张金凤.海啸波近岸共振响应的数值模拟及分析[J].防灾减灾工程学报,2010,30(2):147-151.Zhang Jinfeng.Numerical simulation and analysis of offshore resonance of tsunami waves[J].Journal of Disaster Prevention and Mitigation Engineering,2010,30(2):147-151.
[8] 潘文亮,王盛安,孙璐,等.2010年智利和2011年日本海啸在华南沿岸的实测海啸波形和特征[J].热带海洋学报,2014,33(6):17-23.Pan Wenliang,Wang Sheng’an,Sun Lu,et al.Observed waveform and characteristics of the 2010 Chile and 2011 Japan tsunamis near the coast of South China[J].Journal of Tropical Oceanography,2014,33(6):17-23.
[9] Dao M H,Tkalich P.Tsunami propagation modelling-a sensitivity study[J].Natural Hazards and Earth System Sciences,2007,7(6):741-754.
[10] Yamazaki Y,Cheung K,Lay T.Modeling of the 2011 tohoku near-field tsunami from finite-fault inversion of seismic waves[J].Bulletin of the Seismological Society of America,2013,103(2B):1444-1455.
[11] Ramírez-Herrera M T,Corona N,Ruiz-Angulo A,et al.The 8 September 2017 Tsunami Triggered by the MW8.2 Intraplate Earthquake,Chiapas,Mexico[J].Pure and Applied Geophysics,2018,175(1):25-34.
[12] Torrence C,Compo G P.A practical guide to wavelet analysis[J].Bulletin of the American Meteorological Society,1998,79(1):61-78.
[13] Proudman J.Dynamical Oceanography[M].London:Methuenm,1953.
[14] Yamazaki Y,Cheung K F.Shelf resonance and impact of near-field tsunami generated by the 2010 Chile earthquake[J].Geophysical Research Letters,2011,38(12):L12605.
[15] Mansinha L,Smylie D E.The displacement fields of inclined faults[J].Bulletin of the Seismological Society of America,1971,61(5):1433-1440.
[16] Steketee J A.On volterra's dislocations in a semi-infinite elastic medium[J].Canadian Journal of Physics,1958,36(2):192-205.
[17] Okada Y.Surface deformation due to shear and tensile faults in a half-space[J].Bulletin of the Seismological Society of America,1985,75(4):1135-1154.
[2] 任智源,原野,赵联大,等.2016年全球地震海啸监测预警与数值模拟研究[J].海洋科学,2017,41(6):98-110.Ren Zhiyuan,Yuan Ye,Zhao Lianda,et al.Monitoring,early warning and numerical study of global tsunamis in 2016[J].Marine Sciences,2017,41(6):98-110.
[3] 闪迪,王培涛,任智源,等.有限断层模型在2015年9月16日智利Mw8.3级地震海啸数值模拟中的应用与评估[J].海洋学报,2017,39(11):49-60.Shan Di,Wang Peitao,Ren Zhiyuan,et al.Application and evaluation of the 16 September 2015 Illapel,Chile Mw8.3 earthquake finite fault rupture model from numerical simulation[J].Haiyang Xuebao,2017,39(11):49-60.
[4] 王培涛,于福江,赵联大,等.2011年3月11日日本地震海啸越洋传播及对中国影响的数值分析[J].地球物理学报,2012,55(9):3088-3096.Wang Peitao,Yu Fujiang,Zhao Lianda,et al.Numerical analysis of tsunami propagating generated by the japan MW9.0 earthquake on Mar.11 in 2011 and its impact on China coasts[J].Chinese Journal of Geophysics,2012,55(9):3088-3096.
[5] 于福江,原野,赵联大,等.2010年2月27日智利8.8级地震海啸对我国影响分析[J].科学通报,2011,56(3):239-246.Yu Fujiang,Yuan Ye,Zhao Lianda,et al.Evaluation of potential hazards from teletsunami in China:Tidal observations of a teletsunami generated by the Chile 8.8 Mw earthquake[J].Chinese Science Bulletin,2011,56(11):1108-1116.
[6] Omira R,Baptista M A,Lisboa F.Tsunami characteristics along the Peru-Chile trench:analysis of the 2015 MW8.3 Illapel,the 2014 MW8.2 Iquique and the 2010 MW8.8 Maule Tsunamis in the Near-field[J].Pure and Applied Geophysics,2016,173(4):1063-1077.
[7] 张金凤.海啸波近岸共振响应的数值模拟及分析[J].防灾减灾工程学报,2010,30(2):147-151.Zhang Jinfeng.Numerical simulation and analysis of offshore resonance of tsunami waves[J].Journal of Disaster Prevention and Mitigation Engineering,2010,30(2):147-151.
[8] 潘文亮,王盛安,孙璐,等.2010年智利和2011年日本海啸在华南沿岸的实测海啸波形和特征[J].热带海洋学报,2014,33(6):17-23.Pan Wenliang,Wang Sheng’an,Sun Lu,et al.Observed waveform and characteristics of the 2010 Chile and 2011 Japan tsunamis near the coast of South China[J].Journal of Tropical Oceanography,2014,33(6):17-23.
[9] Dao M H,Tkalich P.Tsunami propagation modelling-a sensitivity study[J].Natural Hazards and Earth System Sciences,2007,7(6):741-754.
[10] Yamazaki Y,Cheung K,Lay T.Modeling of the 2011 tohoku near-field tsunami from finite-fault inversion of seismic waves[J].Bulletin of the Seismological Society of America,2013,103(2B):1444-1455.
[11] Ramírez-Herrera M T,Corona N,Ruiz-Angulo A,et al.The 8 September 2017 Tsunami Triggered by the MW8.2 Intraplate Earthquake,Chiapas,Mexico[J].Pure and Applied Geophysics,2018,175(1):25-34.
[12] Torrence C,Compo G P.A practical guide to wavelet analysis[J].Bulletin of the American Meteorological Society,1998,79(1):61-78.
[13] Proudman J.Dynamical Oceanography[M].London:Methuenm,1953.
[14] Yamazaki Y,Cheung K F.Shelf resonance and impact of near-field tsunami generated by the 2010 Chile earthquake[J].Geophysical Research Letters,2011,38(12):L12605.
[15] Mansinha L,Smylie D E.The displacement fields of inclined faults[J].Bulletin of the Seismological Society of America,1971,61(5):1433-1440.
[16] Steketee J A.On volterra's dislocations in a semi-infinite elastic medium[J].Canadian Journal of Physics,1958,36(2):192-205.
[17] Okada Y.Surface deformation due to shear and tensile faults in a half-space[J].Bulletin of the Seismological Society of America,1985,75(4):1135-1154.