智利M_W8.8地震同震重力梯度变化
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摘要
利用GFZ Release 05卫星重力GRACE观测数据,计算2010年2月27日智利MW8.8逆冲型地震的同震重力和重力梯度变化,分析其分布特征,可知:由GRACE探测到的同震重力变化在断层俯冲区域可达-9.5μGal,断层隆升区域可达+3.5μGal,结果与利用SNREI地球模型的位错理论计算的同震重力变化较一致,说明利用GFZ Release05 DDK5滤波数据,更能精确的反映同震重力场变化;GRACE检测的智利地震同震径向重力梯度变化Trr最大可达-600μE,位于发震断层东侧俯冲区域;通过对同震重力梯度分布特征分析,初步判断发生同震物质迁移的区域范围在断层俯冲区域为(67°—72°W,33°—38°S),在断层隆升区域为(73°—77°W,35°—39°S)。
We calculate the co-seismic gravity and gravity gradient changes correlate with Chile MW 8.8 earthquake using the satellite gravity model of GFZ release 05 which had processed by DDK5 decorrelate filtering. By analyzing the Characteristics of the results, we draw the following conclusions:1 The co-seismic gravity changes are negative in fault subduction zone, which can reach-9.5μGal at peak. In fault uplift zone, it shows positive changes, and the maxim value is +3.5μGal. Our co-seismic gravity change agree very well with that calculated using a dislocation theory for a spherical earth model, which means the GFZ release 05 data have a better resolution of the gravity change for this event. 2 The different gravity gradient has different response to this event. By analyzing we can draw a preliminary conclusions that the area where has been through co-seismic material migration is located in(67 °—72 °W, 33 °—38 °S) for the fault subduction zone, and(73°—77°W, 35°—39°S) for fault uplift zone. And the magnitude of material migration has the character of higher in the center and lower around it.
We calculate the co-seismic gravity and gravity gradient changes correlate with Chile MW 8.8 earthquake using the satellite gravity model of GFZ release 05 which had processed by DDK5 decorrelate filtering. By analyzing the Characteristics of the results, we draw the following conclusions:1 The co-seismic gravity changes are negative in fault subduction zone, which can reach-9.5μGal at peak. In fault uplift zone, it shows positive changes, and the maxim value is +3.5μGal. Our co-seismic gravity change agree very well with that calculated using a dislocation theory for a spherical earth model, which means the GFZ release 05 data have a better resolution of the gravity change for this event. 2 The different gravity gradient has different response to this event. By analyzing we can draw a preliminary conclusions that the area where has been through co-seismic material migration is located in(67 °—72 °W, 33 °—38 °S) for the fault subduction zone, and(73°—77°W, 35°—39°S) for fault uplift zone. And the magnitude of material migration has the character of higher in the center and lower around it.
引文
周新,孙文科,付广裕.重力卫星GRACE检测出2010年智利MW 8.8地震的同震重力变化[J].地球物理学报,2011,54(7):1745-1749.
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Novák P,Grafarend E W.The effect of topographical and atmospheric masses on spaceborne gravimetric and gradiometric data[J].Studia Geophysica et Geodaetica,2006,50(4):549-582.Saad A H.Understanding gravity gradients-A tutorial[J].TheLeading Edge,2006,25(8):942-949.
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Dahle C.GFZGRAC Elevel-2processing standards document forlevel-2 product release 0005[M].Deutsches Geo Forschungs Zentrum GFZ,2013.
Eshagh M,Sj?berg L E.Atmospheric effects on satellite gravity gradiometry data[J].Journal of Geodynamics,2009,47(1):9-19.
Farías M,Vargas G,Tassara A et al.Land-level changes produced by the MW 8.8 2010 Chilean earthquake[J].Science,2010,329(5994):916-916.
Gross R S,Chao B F.The gravitational signature of earthquakes[M]//Gravity,Geoid and Geodynamics 2000.Springer BerlinHeidelberg,2002:205-210.
Heki K,Matsuo K.Coseismic gravity changes of the 2010 earthquake in central Chile from satellite gravimetry[J].GeophysicalResearch Letters,2010,37(24).
Kendrick E,Bevis M,Smalley Jr R et al.The Nazca–South America Euler vector and its rate of change[J].Journal of SouthAmerican Earth Sciences,2003,16(2):125-131.
Kusche J,Schmidt R,Petrovic S et al.Decorrelated GRACE time-variable gravity solutions by GFZ,and their validation using ahydrological model[J].Journal of Geodesy,2009,83(10):903-913.
Novák P,Grafarend E W.The effect of topographical and atmospheric masses on spaceborne gravimetric and gradiometric data[J].Studia Geophysica et Geodaetica,2006,50(4):549-582.Saad A H.Understanding gravity gradients-A tutorial[J].TheLeading Edge,2006,25(8):942-949.
Sun W,Okubo S.Coseismic deformations detectable by satellite gravity missions:A case study of Alaska(1964,2002)andHokkaido(2003)earthquakes in the spectral domain[J].Journal of Geophysical Research:Solid Earth(1978-2012),2004,109(B4).
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