On physical modeling of tidal impact upon seismic emission

Saltykov V.A.1, Zaitsev V.Yu.2, Kugaenko Yu.A.1, Matveev L.A.2, Patonin A.V.3
  1. Kamchatkan Branh of Geophysical Survey of RAS, Petropavlovsk-Kamchatsky
  2. Institute of Applied Physics of RAS, N. Novgorod
  3. Geophysical Observatory BOROK of the United Institute of Physics of the Earth of RAS, Borok

The aim of this report is to investigate the opportunity to monitor stress-strain state of a medium prior to
an earthquake using the parameters of tidal variation of background niose and of high-frequency seismic noise
(HFSN). During our long-term study of HFSN, we detected a stable synchronization of the tidal component
of HFSN with gravitational potential before the strongest local earthquakes, occurred within the distance of
400 km from the registration point. The main question under consideration is: what physical mechanism can
provide the appearance of the synchronization and the observed depth of modulation of HFSN of several per-
centage level and more due to weak tidal deformations, not exceeding 1.0E-8. Test series for model rock samples
(sandstone) was carried out in the conditions of uniaxial and uniform compression and changeable parameters
of modulatory influences and background leading. Areas of acoustic emission change with modulatory period
were determined. We detected the areas of different response of acoustic emission on repeating loading imitating
tides; it is associated with different stages of stress-strain state of a sample. The mechanism of tidal modulation
of HFSN on the basis of the model of rheological level medium is suggested. The model of amplitude-dependent
absorption is considered. The analysis of energy loss of low-amplitude seismic waves due to thermoelastic ab-
sorption on cracks was carried out considering surface irregularities.