Resumo

CASTRO, Henry Montecino; FERREIRA, Vagner Gonçalves  e  FREITAS, Sílvio Rogério Correia de. Deformation analysis by varying of the geopotential: a case study for the Maule Earthquake (M_w 8.8) based on monthly data of GRACE mission. Bol. Ciênc. Geod. [online]. 2012, vol.18, n.1, pp. 86-100. ISSN 1982-2170.  http://dx.doi.org/10.1590/S1982-21702012000100005.

Chile is a natural laboratory for studies of Geodynamics due to of the broad and varied of tectonic events. A notable case is the deformation produced from the seismic event of magnitude M_w 8,8, named earthquake the Maule. The epicenter was located 60 km to South of Constitucion, a region that had shown considerable velocities recorded by GNSS. Several studies related to the geophysical signal generated by the earthquake have been made, particularly those explored by GNSS and InSAR, and one based on satellite gravimetry. However, these studies have presented difficulties concerning time series analysis. Most of the series of GNSS positioning have been discontinued by the event and therefore there are only series either before or after the event. This study presents an independent alternative for the quantification of vertical deformation of the crust based on variations of the potential anomalous provided by Stokes coefficients of the monthly GRACE mission. Differences in height anomaly from September 2009 to May 2011, obtained by the temporal variation of the Stokes coefficients regarded a static solution were calculated for four stations (LLFN, ANTC, CONZ, VALP). The Stokes coefficients were used in an expansion up to degree and order 45. The hydrologic signal was removed by means of EWT (Equivalent Water Thickness) after a Gaussian smoothing filter of 600 kmwas applied. The results obtained after filtering are higly consistent to those reported by GNSS in other investigations.

Palavras-chave : Maule Earthquake; Monitoring; Deformation of the Crust; GRACE.