Goce derived geoid changes before the Pisagua 2014 earthquake

ÁLVAREZ, ORLANDO; GIMENEZ, MARIO; FOLGUERA, ANDRÉS; GUILLEN, SOFIA; TOCHO, CLAUDIA

Geodesy and Geodynamics

advancing research evolving planet

Año: 2018 vol. 9 p. 50 - 56

1674-9847

The analysis of space e time surface deformation during earthquakes reveals the variable state of stressthat occurs at deep crustal levels, and this information can be used to better understand the seismiccycle. Understanding the possible mechanisms that produce earthquake precursors is a key issue forearthquake prediction. In the last years, modern geodesy can map the degree of seismic coupling duringthe interseismic period, as well as the coseismic and postseismic slip for great earthquakes along subductionzones. Earthquakes usually occur due to mass transfer and consequent gravity variations, wherethese changes have been monitored for intraplate earthquakes by means of terrestrial gravity measurements.When stresses and correspondent rupture areas are large, affecting hundreds of thousands ofsquare kilometres (as occurs in some segments along plate interface zones), satellite gravimetry databecome relevant. This is due to the higher spatial resolution of this type of data when compared toterrestrial data, and also due to their homogeneous precision and availability across the whole Earth.Satellite gravity missions as GOCE can map the Earth gravity field with unprecedented precision andresolution. We mapped geoid changes from two GOCE satellite models obtained by the direct approach,which combines data from other gravity missions as GRACE and LAGEOS regarding their best characteristics.The results show that the geoid height diminished from a year to five months before the mainseismic event in the region where maximum slip occurred after the Pisagua Mw ¼ 8.2 great megathrustearthquake. This diminution is interpreted as accelerated inland-directed interseismic mass transferbefore the earthquake, coinciding with the intermediate degree of seismic coupling reported in theregion. We highlight the advantage of satellite data for modelling surficial deformation related to preseismicdisplacements. This deformation, combined to geodetical and seismological data, could beuseful for delimiting and monitoring areas of higher seismic hazard potential.© 2017 Institute of Seismology, China Earthquake Administration, etc. Production and hosting by ElsevierB.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND