Preliminary Results of Measurements with a Laser Extensometer at Obninsk Obseravatory

Current strain analysis for Obninsk observatory are presented. An extension rate of 5 × 10-9/y was recorded for the central part of European Russia using satellite geodesy. Preliminary results for a new laser extensometer installed in the Obninsk underground gallery (55.12° N, 36.59° E) are presented. The instrument with a 36 m base was an installed at depth of 30 m, along latitude and longitude. In this case, both seismic waves from earthquakes, tidal strain, and long-period signals associated with tectonic processes are recorded. Original strain data presented for July–September 2024 year period. Analysis of record noise is developed. Microseismic waves with periods from 10 to 50 s are presented. The long-period part with periods from 18 to 38 and 291 h connected with meteorological effects. Noise influence was excepted and for tidal analysis of difference strain a 70-day record are used. The Shida tidal parameter is studied. As a result of the study, it is shown that old results by measurements with gravimeters, tube-extensometers, and tiltmeters are related to old elastic tidal models. Our new results show accordance with DDW99 Earth tidal model with viscosity-elastic mantle.