The Co-seismic Effects of 2010 Mw 8.8 Maule Earthquake

Abstract:

The 2010 Chile Maule earthquake ranks as the sixth largest earthquake ever to be recorded by a seismograph. Plane assumption is inapplicability to the exceptionally large earthquakes, in this paper, with the finite element method considering Earth’s layered structure and curvature, co-seismic deformation field and stress field are calculated. Based on the Coulomb stress change, seismic activity of surrounding faults and triggering of aftershocks is estimated. The results show that: the effects of Earth’s layered structure and curvature on co-seismic horizontal and vertical displacement are significant. The plane layered model or plane half-space model may underestimate the far-field co-seismic displacement and strain near the equator and overestimate and underestimate the far-field displacement and strain near Antarctica, respectively. The range of influence of co-seismic displacement is about thousands of kilometers, relatively large horizontal displacements locate on the northwest and southeast of the seismic fault. Horizontal displacement in One-half of South America is about the magnitude order of 0.5 mm. Stress drop caused by this earthquake in Central Argentina is equivalent to 5-10 years tectonic stress accumulation while in Northern Argentina and Southern Argentina is equivalent to 1-5 years tectonic stress release. Coulomb stress change in earthquake fractured zone is equivalent to 15 years tectonic stress release which means next great earthquake will not come at this region in short time. Coulomb stress change in unfracture regions near the fracture zone is equivalent to 15 years tectonic stress accumulation, which means the seismicity increasing. Coulomb stress change on optimally orientated faults are calculated, 66.2% of aftershocks occur in regions where the failure stress exceed 10 kPa. The great Mw 6.9 and Mw 7.0 aftershocks near Pichilemu were triggered by the great Maule earthquake.