STRESS REGIME AND MICROGRAVITY RELATED TO MAJOR EARTHQUAKES

Abstract

Generally, GPS and InSAR data are used in monitoring surface deformation that results from an earthquake. This surface deformation is a small manifestation of overall changes that take place within the subsurface. Present study is aimed at tensorial analysis of co-seismic stress changes associated with an earthquake. Three significant earthquakes, namely Sumatra earthquake 2004. Japan earthquake 2011 and recent Nepal earthquake 2015 were considered for this study. Variations in six independent components of symmetric stress tensor (ar , a22. a33. U12, a13 and (T23) in a half-space have been generated and analysed for the above mentioned earthquakes rupture models, and an attempt is made to correlate aftershock distribution with the modelled stress changes. Results in this regard showed similarity between aftershock pattern and a22 component of modelled stress change, which showed maximum variation compared to other components. Stress changes in a material cause deformation and theoretically this deformation in turn leads to gravity variation. By considering the global coverage by satellite missions like GRACE and GOCE, they may provide invaluable additional data which can constrain the seismic stress change models. An attempt is also made to correlate modelled co-seismic stress changes with satellite gravity signals for Sumatra earthquake 2004 and Japan earthquake 2011. Achieved results in this regard also indicated most similarity with a22 component of modelled stress change.