Impact of megathrust geometry on inversion of coseismic slip from geodetic data: Application to the 1960 Chile earthquake

• Published in: Geophysical research letters Vol. 36; no. 16; pp. L16310 - n/a
• Main Authors: Moreno, M. S., Bolte, J., Klotz, J., Melnick, D.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 01-08-2009; Blackwell Publishing Ltd; John Wiley & Sons, Inc
• Subjects: Aseismic zones; Dislocation models; Earth sciences; Earth, ocean, space; Earthquake interaction, forecasting, and prediction; Earthquakes; Exact sciences and technology; Faults; Finite element method; Geodesy and Gravity; Geodetics; Geophysics; inversion; Mathematical analysis; Mathematical models; Plate tectonics; Rock deformation; Seismic activity; Seismic cycle related deformations; Seismic phenomena; Seismicity and tectonics; Seismology; Slip; Subduction zones; South America; Chile; inversion; slip; inverse problem; geometry; earthquakes
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2009GL039276

We analyze the role of megathrust geometry on slip estimation using the 1960 Chile earthquake (MW = 9.5) as an example. A variable slip distribution for this earthquake has been derived by Barrientos and Ward (1990) applying an elastic dislocation model with a planar fault geometry. Their model shows slip patches at 80–110 km depth, isolated from the seismogenic zone, interpreted as aseismic slip. We invert the same geodetic data set using a finite element model (FEM) with precise geometry derived from geophysical data. Isoparametric FEM is implemented to constrain the slip distribution of curve‐shaped elements. Slip resolved by our precise geometry model is limited to the shallow region of the plate interface suggesting that the deep patches of moment were most likely an artifact of the planar geometry. Our study emphasizes the importance of fault geometry on slip estimation of large earthquakes.