Initiation of acoustic emission in fluid-saturated sandstone samples

A rock behavior experiment with uniaxial compression revealed the effect of acoustic activity in loaded fluid-saturated Berea sandstone samples in response to an electric current. It is established that it is substantially intensified in periods of the current impact and decreases after its cut-off. The current impact also results in a growth of radial deformation indicating an increase in the sample volume. The effect of acoustic activation increases in response to increased heat emitted by the electric current during its flow through the sample, which allows the discovered effect to be explained by initiation of its destruction due to thermal expansion of the fluid in rock interstices and fissures.     

Erratum to: Seasonal Variations in the b-Value of the Reservoir-Triggered Seismicity in the Koyna–Warna Region,Western India

Izvestiya, Physics of the Solid Earth - An Erratum to this paper has been published: https://doi.org/10.1134/S1069351322090014     

Variations in Ultrasonic Signal Spectra for Triaxial Testing of Rock Samples

Izvestiya, Physics of the Solid Earth - Abstract—Experiments on sandstone, basalt and granite were carried out on a controlled hydraulic press under triaxial loading conditions at confining...     

A laboratory instrumental complex for studying the physics of the destruction of rocks

An up-to-date laboratory investigation complex for testing rock samples under controlled uniaxial and triaxial compression is designed. A wide range of loading modes of samples allows one to simulate various natural seismic regimes. The complex is equipped with systems intended for measuring and recording service and physical parameters, namely, axial, uniform, and pore pressure, axial and radial deformation, velocities of longitudinal waves along 16 travel paths, and waveforms of separate acoustic events, recorded by 16 sensors. The system ensures the continuous recording of the acoustic emission stream. Data of all measuring systems are synchronized with time. The rock samples are tested in the automatic mode, which can be optionally corrected during experiments. The experimental results are stored in a single database, which contains both raw and processed data (loading history, catalogs and bulletins of acoustic events, 3D graphic visualizations of pressure-wave velocity distributions in the sample volume, etc.). The application of the complex for the laboratory modeling of the seismic regime is illustrated by a number of practical examples.     

Staging of acoustic emission in laboratory modeling of tidal effects in seismicity

Experiments on sandstone destruction were carried out in order to reproduce the influence of Earth tide on seismicity under controlled laboratory conditions. The discovery of staging in acoustic response of destruction of a specimen to an external weak periodic effect is decided as the main result of the experiments. Moreover, the different stages are related to the different conditions of the specimen during the destruction process.     

Initiation of Rock Fracture by Fluids of Different Viscosities

Izvestiya, Physics of the Solid Earth - Abstract—The acoustic emission (AE) patterns observed in laboratory conditions at the initiation of fracture in rock samples by fluids of different...     

Seasonal Variations in the b-Value of the Reservoir-Triggered Seismicity in the Koyna–Warna Region,Western India

Izvestiya, Physics of the Solid Earth - Abstract—The analysis of the local earthquake catalog revealed fine features in the behavior of seasonal components of induced seismicity in the...     

Laboratory Modeling of Aftershock Sequences: Stress Dependences of the Omori and Gutenberg–Richter Parameters

Izvestiya, Physics of the Solid Earth - Laboratory experiments on studying the aftershock regime are carried out on sandstone specimens at different levels of axial loading and uniform compression...