Dependence of Post Seismicity on Prior StressEnvironment, and It's Correlation with Earth Processes

The prediction of forthcoming earthquakes is crucial formitigation of seismic hazards, which remains unsuccessfuldespite rigorous efforts. The correlation of postseismicity with temporal variation of lithospheric stressby precedent large earthquakes is examined. The Coulombstress changes of earthquakes with magnitudes greaterthan 7.0 during 1976-2013 is calculated over the globe.The seismicity in the following year is compared with theinduced Coulomb stress changes by earthquakes withmagnitudes of 7.0 or greater during 1976 to the previousyear. The seismicity of events with magnitude of 4 to 5in the following year is found to be negativelycorrelated with the cumulative Coulomb stress changes upto previous year. In other words, high seismicity isobserved in regions of large negative cumulative Coulombstress changes. Such negative correlations are observedfeature is also observed in regions of positive Coulombstress changes. The observation suggests that regionswith weakly-discharged stress produce more seismicity tocompensate the cumulated energy in the media. Thecorrelation of Coulomb stress changes with physicalproperties including plate velocities, plate ages, slabdipping angles and heat flows is investigated. It isobserved that the largest stress drop occurs in plateboundaries with high convergent speeds. Examples includethe 2010 M8.8 Maule earthquake, the 2004 M9.1Sumatra-Andaman earthquake, and the 2011 M9.0 Tohoku-Okiearthquake. It is observed that The cumulative Coulombstress changes have strong correlations with the platevelocities and strain rates, while weak correlations withthe plate ages, slab dipping angles and heat flows. Theobservation suggests that large stress accumulation mayoccur at regions of high plate speeds where highlithostatic strain rates are expected.