摘要
Data obtained by GRACE(Gravity Recovery and Climate Experiment) have been used to invert for the seismic source parameters of megathrust earthquakes under the assumption of either uniform slip over an entire fault or a point-like seismic source.Herein, we further extend the inversion of GRACE long-wavelength gravity changes to heterogeneous slip distributions during the 2011 Tohoku earthquake using three fault models:(Ⅰ) a constant-strike and constant-dip fault,(Ⅱ) a variable dip fault, and(Ⅲ) a realistically varying strike fault. By removing the post-seismic signal from the time series, and taking the effect of ocean water redistribution into account, we invert for slip models I, II, and III using co-seismic gravity changes measured by GRACE, de-striped by DDK3 decorrelation filter. The total seismic moments of our slip models, with respective values of 4.9×10^(22) Nm, 5.1×10^(22) Nm, and 5.0×10^(22) Nm, are smaller than those obtained by other studies relying on GRACE data. The resulting centroids are also located at greater depths(20 km, 19.8 km,and 17.4 km, respectively). By combining onshore GPS, GPS-Acoustic, and GRACE data, we obtain a jointly inverted slip model with a seismic moment of 4.8×10^(22) Nm, which is larger than the seismic moment obtained using only the GPS displacements. We show that the slip inverted from low degree space-borne gravimetric data, which contains information at the ocean region, is affected by the strike of the arcuate trench. The space-borne gravimetric data help us constrain the source parameters of a megathrust earthquake within the frame of heterogeneous slip models.
Data obtained by GRACE(Gravity Recovery and Climate Experiment) have been used to invert for the seismic source parameters of megathrust earthquakes under the assumption of either uniform slip over an entire fault or a point-like seismic source.Herein, we further extend the inversion of GRACE long-wavelength gravity changes to heterogeneous slip distributions during the 2011 Tohoku earthquake using three fault models:(Ⅰ) a constant-strike and constant-dip fault,(Ⅱ) a variable dip fault, and(Ⅲ) a realistically varying strike fault. By removing the post-seismic signal from the time series, and taking the effect of ocean water redistribution into account, we invert for slip models I, II, and III using co-seismic gravity changes measured by GRACE, de-striped by DDK3 decorrelation filter. The total seismic moments of our slip models, with respective values of 4.9×10^(22) Nm, 5.1×10^(22) Nm, and 5.0×10^(22) Nm, are smaller than those obtained by other studies relying on GRACE data. The resulting centroids are also located at greater depths(20 km, 19.8 km,and 17.4 km, respectively). By combining onshore GPS, GPS-Acoustic, and GRACE data, we obtain a jointly inverted slip model with a seismic moment of 4.8×10^(22) Nm, which is larger than the seismic moment obtained using only the GPS displacements. We show that the slip inverted from low degree space-borne gravimetric data, which contains information at the ocean region, is affected by the strike of the arcuate trench. The space-borne gravimetric data help us constrain the source parameters of a megathrust earthquake within the frame of heterogeneous slip models.
基金
supported financially by the National Natural Science Foundation of China (No.41574021,41474059,41331066,41774088,and 41174063)
a research grant from the Institute of Crustal Dynamics,China Earthquake Administration (No.ZDJ2017-23)
the CAS/CAFEA International Partnership Program for Creative Research Teams (No.KZZD-EW-TZ-19)
the Key Research Program of Frontier Sciences CAS (Chinese Academy of Sciences) (QYZDY-SSW-SYS003)
the SKLGED foundation (SKLGED2014-1-1-E)
the GOCE Italy Project (the Italian Space Agency and the European Space Agency Endorsement)
the China Postdoctoral Science Foundation (No.133014)
