Monitoring of the tidal variations in the seismic and hydrogeological data collected at the East European Platform Besedina A.N., Kabychenko N.V., Gorbunova E.M., Svinzov I.S. Moscow Institute of Physics and Technology (State University), Moscow, Russia Institute of Geosphere Dynamics of Russian Academy of Sciences, Moscow, Russia 33rd GA ESC, August 2012

Review Correlations between the tidal deformation and the microseismic noise parameters [Kishkina, Spivak, 2003 ]; The influence of the tides on the rate of the oil reservoir’s recovery [Mirzoev et al., 2008 ]; The influence of the tides on the initiation of the weak seismicity [Stroup et al., 2007 ] and on the origination of megaearthquakes precursors [Tanaka, 2010]; Hydrogeological processes in the system “well-aquifer” in high seismicity [Kopylova et al., 2008, 2010]; The response of the reservoir and atmospheric pressure due to the tidal waves in low-magnitude seismicity [Lyubushin et al., 1997]; Variation in the fluid properties of the fractured reservoir under tidal stresses is one of the most important mechanisms of changing deformation conditions [Brodsky et al., 2003; Kocharyan et al., 2011].

The variations of the tides in the hydrogeological and seismic data at the platform Detection of the basic mechanism of the deformation of fluid saturated reservoir due to external factors

GFO IDG RAS “Mikhnevo” LMP308i (Germany) Registration precision – 0.1 mm Sampling rate – 1 Hz Broadband sensor STS-2 ( Hz) Absolute pressure sensor Registration precision – 0.1 gPa

Average transmissivity 3.6 m 2 /day Head pressure - 24 m. Hydrogeological cross-section of the territory GFO IDG RAS “Mikhnevo” S N

K h O h M h Investigation methods 1-Oct8-Oct 15-Oct 22-Oct29-Oct Groundwater level variations & atmospheric pressure - coefficient of barometric efficiency - removal of the influence of the atmospheric pressure on the underground water level fluctuations [Vinogradov et al., 2011] Seismic data - expansion of the range of the seismometer in the tidal frequency with account for the gravity properties of the sensor [Kabychenko et.al., 2011; Rykov, 1993] - vertical deformation is obtained by vertical displacement; theoretical relation was achieved by [Kabychenko,2011] Filtration of the underground water level, ground deformation and atmospheric pressure during the band of the period 8-26 hours pressure water level free of pressure underground water level

Amplitude spectrum of the water level fluctuations, Average monthly variations of the amplitude of the tidal waves in the underground water level K 1 (23.935h) (25.819h) (12.421h) Man-made regime (after pump)

Change in regime of water level 1. Stable period of the underground water level 3. Decrease of the potentiometric surface 2. Rise of the potentiometric surface A= 0.2mH= 23.1m A= 0.16m A= 0.09m H= 24.0m H= 23.5m H= 23.1m H= 22.8m H= 20.8m A= 0.23m A= 0.14m A= 0.47m H - head pressureA – amplitude of the underground water level

Amplitude analysis stable period of the underground water level rise of the potentiometric surface decrease of the potentiometric surface K 1 (23.935h) O 1 ( h) M 2 ( h)

Lunar – solar tides (8-26 hours) 10 Lunar cycle: 15/10/08 – full moon; 21/10/08 – 4th quarter; 29/10/08 – new moon; 6/11/08 – 2nd quarter. pressure underground water level deformation

Phase analysis stable period of the underground water level rise of the potentiometric surface decrease of the potentiometric surface H min =20.8m H max =24.0m K 1 (23.935h) O 1 ( h) M 2 ( h) Phase shift, degree Amplitude of the tidal wave in the underground water level, mm

Conclusions The technique of the precision data processing of the water level fluctuations in the range of the tidal waves was improved. The method of the selection of the different tidal waves in seismic data was developed and tested. This technique can underlie a way of determining the ranges of the variation of the vertical deformation of rock due to the tides. Seasonal variations of the tidal waves (K 1, O 1, M 2 ) in the different filtration conditions of the underground water (quasi-stationary and non- stationary) were analyzed. The most significant variations up to 3 mm are in the wave K 1 in spring and summer, in contrast to autumn and winter. At the waves of the lunar type O 1 and M 2 seasonal variations are weakly assign. Amplitude analysis of the tidal components (M 2, K 1 and O 1 ) of the underground water levels relative to the vertical deformation showed that the hydrogeological properties of the reservoir affected by two factors: the conditions of supply of the aquifer and the stress-strain state of the rock. Phase shift for the different types of the tidal waves is determined: for the wave of M 2 it reaches -0.5 h, for O h and for K 1 varies from -3.3h to 2.2h. Evaluation of the phase delay between the tidal components of hydrogeological and seismic data underlie the determining the permeability of collector and its variation due to the exogenous factors.

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