Geodetic aspects of seismological phenomena: Fid-Bau Portal

Geodetic aspects of seismological phenomena

Varga, Peter / Denis, Carlo

Abstract Seismology is related to many problems of geodesy. The energy production of our planet is rather close to energy consumption of the Earth so that the energy balance can be disturbed significantly by minor processes acting on global scale. From this point of view the effect of tidal triggering of earthquakes is discussed by the study of tidal stress tensor components expressed in spherical system of coordinates. Tidal friction influences through the despinning of the axial rotation the geometrical flattening. This flattening variation causes stresses along the longitude and this phenomenon is closely related to the seismic energy release. Until now there is no unambiguous success to relate changes of the Earth orientation parameters with seismicity. Present-day accuracy of the length of day variations is not sufficient yet to detect spin variation generated by the greatest earthquakes. The polar motion is probably more sensitive to earthquakes and then there is a chance to detect the polar displacements generated by seismic events. In the last section of the present contribution, the strain rates derived from the static seismic moments and from space geodetic observations are compared. Future geodetic strain rate data will be useful in earthquake prediction.