Science Seminars

Long-term Variations of Tidal Force, Tides Generated Stresses and Deformations, and their Geodynamic Implications

Speaker: Lev Maslov
Date: Thursday, Feb 23, 2012
Time: 4:00 PM to 5:00 PM
Location: LSTB-299, Auditorium

Seminar Abstract:

It is shown that the tidal force can be decomposed into two components: the Keplerian component and the Perturbed component. The Perturbed component of the tidal force variation was calculated, and it was shown that the observed periodicity, 206 and 412 days, of atmospheric and hydrosphere tides, Earth and Moon seismicity, result from variations of the Perturbed component of tidal force. The amplitude of the Perturbed component of the tidal force is 19 x 10^-8 N/kg. It is the same order of magnitude as the amplitude of the Keplerian component of the tidal force: 58 x 10^-8 N/kg. It follows that the Perturbed component of the variation of the tidal force must always be taken into consideration along with the Keplerian component in geodynamical constructions involving tides.

A number of mechanisms of direct transformation of tidal deformations into tectonic deformations and motions are considered.

Components of the stress tensor were calculated for an elastic shell with variable oblateness. It was shown that a change in oblateness of ± 10^-5 resulted in stresses of ±1 MPa. The principal stresses in a shell, σ1 and σ2, are oriented in N-S and E-W directions, while corresponding shear stresses, τ12 and τ21, are oriented in NE-SW and NW-SE directions. This is in a good agreement with the regmatic system of Earth’s crust faults and lineaments observed.