Results of atmospheric-lithospheric observations of acoustic radiation in Kamchatka

Simultaneous atomspheric-lithospheric acoustic observations have been carried out during autumn-spring periods of 2017-2019 in Kamchatka at “Karymshina” observation site located in the zone of different-rank tectonic faults. A laser strainmeter-interferometer, a seismoacoustic receiver and a microbarometer were installed to realize the observations. It was detected that during deformation disturbances, geoacoustic signals are generated in rocks with relative deformations of 10-5 – 10-7 at the place of recording. These signals pass the Earth-atmosphere boundary and are recorded in the air by the ground surface

Joint perturbation of geoacoustic, emanation, and atmospheric electric fields at the boundary of the earth’s crust and the atmosphere before an earthquake

The possibility of joint perturbation of geoacoustic, emanation and atmospheric electric fields by the Earth’s crust — atmosphere boundary before an earthquake is considered. In order to detect it, simultaneous registration of these fields was carried out in Kamchatka in August–October 2012. Synchronous anomalous disturbances were recorded 13 days before an earthquake with the magnitude Mw = 5.6 at the distance of 140 km from an epicenter. It may be considered to be a complex short-term precursor

Manifestation features of near-surface sedimentary rock electric and acoustic responses on seismic waves from earthquakes

The results of analysis of near-surface sedimentary rock electric and acoustic responses on seismic waves from five Kamchatka earthquakes with the magnitudes of 4.9 – 7.3 at the distances of 79 – 498 km from epicenters are presented. Manifestation features of these responses, depending upon earthquake magnitude, epicentral distance, source depth and direction to an epicenter, are considered

Some features of acoustic and electric responses of near-surface sedimentary rocks during deformations by seismic waves from strong earthquakes (

Acoustic and electric responses of near-surface sedimentary rocks are considered. They were recorded during the deformations by seismic waves from six earthquakes with magnitude Mw = 6.6-7.7 at the distances of 131-728 km from epicenters in Kamchatka region. Behavior of both responses during soil displacement and displacement velocity during wave propagation are un-der the analysis. The dependence of intensity and character of the responses manifestation on earthquake magnitude and the distance to its source had been discovered by the authors earlier and is confirmed in the work. It was discov-ered that the occurrence of acoustic response in kilohertz range correlates well with the behavior of soil displacement velocity vector and its spectrum

Analysis of manifestation of joint acoustic and electric responses of near-surface sedimentary rocks on the deformation by earthquake seismic waves in the South of Kamchatka

We continue the investigation of earlier discovered joint acoustic and electric responses of near-surface sedimentary rocks on the deformation by earthquake seismic waves. The appearance and absence of this response in earthquakes with the energy class of more than 11.0, which occurred from June 2017 to May 2021 by the eastern coast of Kamchatka in the latitude band of 51.7-54.0° N, are under consideration. From those earthquakes we selected 52 events, the seismic waves of which had rock acoustic response at Karymshina site, IKIR FEB RAS. Occurrences of joint acoustic and electric responses of rocks and manifestations of their low-frequency and high-frequency acoustic responses were analyzed. Applying the nonparametric correlation Spearman analysis, statistically significant relation between the energy class of the earthquakes under consideration and the distance from hypocenter to the observation site was discovered

Simultaneous lithospheric-atmospheric signals of acoustic emission at “Karymshina” site in Kamchatka

We present the results of complex lithospheric-atmospheric investigations of acoustic emission in a seismically active region (Kamchatka peninsula). A laser strainmeter-interferometer, a geophone, a wide-band acoustic system and a microbarometer, installed at Karymshina site (IKIR FEB RAS), are used in the monitoring. Rock deformation, acoustic emission in the near-surface rocks and in the atmosphere by the ground surface are under the consideration. Moreover, we suggest a method to detect acoustic signals recorded simultaneously in the near-surface rocks and in the atmosphere by the ground surface. The method consists in filtration of acoustic signals from the sensors at different frequency sub-ranges from fractions to the first hundreds of hertz followed by detection and accumulation of on 1-second interval. We analyze the data from September 2016 to December 2020. Examples of records of simultaneous acoustic signals in rocks and in the atmosphere are illustrated. The investigation is topical for the construction of a model of lithosphere-atmosphere interaction in a seismically active region

Changes of geoacoustic emission directivity at «Mikizha» site associated with earthquakes in Kamchatka

To investigate high frequency geoacoustic emission, a receiving system based on a compound vector receiver was installed in Kamchatka. It allows the authors to determine the direction of sound wave arrival. In the result of data analysis for the period from August 2008 to January 2016, it was determined that anomalies of geoacoustic emission directivity occur during the majority of the earthquakes with Ks > 9.0 in the South of Kamchatka

Changes of geoacoustic emission directivity at «Mikizha» site associated with earthquakes in Kamchatka

To investigate high frequency geoacoustic emission, a receiving system based on a compound vector receiver was installed in Kamchatka. It allows the authors to determine the direction of sound wave arrival. In the result of data analysis for the period from August 2008 to January 2016, it was determined that anomalies of geoacoustic emission directivity occur during the majority of the earthquakes with Ks > 9.0 in the South of Kamchatka

Electromagnetic and acoustic radiations before Kamchatka earthquake

The most probable cause of simultaneous anomalous radiations in electromagnetic and acoustic fields, different in nature, is intensification of deformation processes during strong earthquake preparation. To verify this fact, simultaneous observations of electromagnetic signals and acoustic emission in the frequency range from 0.1 Hz to 11 kHz were carried out in Kamchatka. In the result of the experiment, radiation bursts appeared about 24 hours before a seismic event with MLH=5.4. Such bursts were not observed on other days within this time of a day in August-September, 2013

Modernization of adaptive matching pursuit method to analyze geophysical signals of pulse nature

The paper is devoted to the development and comparison of different numerical methods which increase the adaptive property and improve the accuracy of matching pursuit algorithm in connection to geoacoustic and electromagnetic signals. At each step of adaptive matching pursuit, a function is chosen which has the highest correlation with an initial signal. Then parameters of a chosen function are refined. The refinement is performed by the help of different grid methods and methods based on gradient direction search. The paper considers the peculiarities of application of sparse approximation methods to geophysical signals of pulse nature and compares different variants of modification of adaptive matching pursuit algorithm