The results of experimental observations over variations of the Earth’s magnetic field recorded by the instruments of the North Caucasus Geophysical Observatory are presented. We observed specific ultralow-frequency quasi-oscillatory waveforms preceding strong distant seismic events in the structure of electromagnetic signals.

Multiparameter geophysical observatory was established in North Caucasus, near Elbrus Volcano, in 2001 by the scientists of Otto Schmidt Institute of Physics of the Earth (IPE) of Russian Academy of Sciences (RAS) with support of Institute for Nuclear Research (INR) RAS and Berbekov Kabardino-Balkar State University (KBSU) to study possible reawakening of volcanism in the region. This paper describes the instrumental equipment of monitoring investigations and data acquisition system forced into application by mid-2007, provides technical characteristics of some devices and their principles. Capacities of the observatory are shown by numerous examples. The most valuable results of instrumental measurements are presented. Based on these data, we studied the tidal deformations, which reflect the structural features of geologic environment of Elbrus volcanic center caused by magmatic bodies. Variations of the earth surface tilt and magnetic field related to the catastrophic Sumatra earthquake December 26, 2004 were recorded, and the spectrum and wavelet analyses were performed. For the first time the wave processes in various geophysical fields that reflect main dynamic features of generation and motion of a catastrophic snow avalanche directly on the observation point were observed and studied. These data underlie the mathematical model of non-linear dynamics of slope flows. Further perspectives of development of the North Caucasus Geophysical Observatory are outlined.

The paper presents results of measurements of surface tide tilts with quartz tiltmeters in the Orenburg gas-condensate field from 1990 to 1992. The value of the tidal factory gamma is shown to be significantly smaller than the estimate obtained from measurements with the same tiltmeters in Obninsk and the Baikal region.

The paper presents results of observations of tidal gravity variations with three Askaniya gravity meters GS-11 no. 124, GS-12 no. 180, and GS-15 no. 220 on the Orenburg gas-condensate field in 1987 and 1988. The tidal factor delta is shown to be significantly underestimated compared to its values obtained in the towns of Novosibirsk, Obninsk, and Talgar.

Tilt variations of the Earth's surface measured in 1985-97 in the underground gallery of the Talaya seismic station (51.68 degrees N and 103.65 degrees E) are interpreted in terms of the Kelvin-Voigt model of viscoelastic crust. Viscosity is estimated on the basis of time-dependent tilt variations in the north-south direction. Effective viscosity was estimated at eta(s) = 3.10(18) Pa.s, proceeding from an empirically obtained delay of T = 6 years. The tectonic stresses corresponding to the measured tilt variations are about 2 MPa.