Prediction of Earthquakes; Considering the Ratio of <i>P-to-S</i> Wave Velocities

Abstract

The ratio of P-to-S-wave velocities (Vp/Vs) is considered as one of the important measures of stressed natural rocks.The changes of this ratio were observed in various earthquakes, however the time of occurrence of the earthquakes were not determined, since the predictions were not combined with other prediction methods. This discriminant provides information about formation and evolution of composition for the earth's crust. In addition, the changes in Vp/Vs before and after earthquakes are the possibly reliable direction to realizing the mechanics and probably predicting earthquakes. However, due to lattice orientations of anisotropic minerals, most of earth's rocks are anisotropic and there exist cracks and thin layerings. The changing patterns in Vp/Vs acquired from seismic propagations can be readily analyzed according to the ray path and the polarization of the (P) pressure and (S) shear waves. The variations in their ratios carry information about stress variations of THE crust of the earth. The arising stresses in rocks are the messengers of possible earthquakes. The stations with monitoring devices and Geographical Positioning System (GPS) upgraded WI-FI remote data acquisition system can serve monitoring stress and movements in the earth's crust. In view present technological developments, the system is reasonable cost effective and prediction of earthquakes can be possible in narrowed time interval. The laboratory tests will be also part of the prediction process.