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The authors generalize and analyze the investigation results of joint anomalies of high-frequency geoacoustic emission and atmospheric electric field by the ground–atmosphere boundary which were detected by them in Kamchatka. These anomalies are observed as geoacoustic emission increases in kilohertz frequency range and bay-like decreases of atmospheric electric field with the sign change which occur close in time during calm weather conditions. It is the authors’ opinion that the common nature of these anomalies is short-time stretching of the near-surface sedimentary rocks at an observation site during unstable tectono-seismic process. A scheme of the detected anomalies formation has been suggested.

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The boundary between the lithosphere and the atmosphere is characterized by specific effects related to the interaction and transformation of various geo physical fields. The persistent various scale variations of these fields reflect the complex relations between their sources and also the properties of solid and gas eous media [1]. These effects are most intensely man ifested in seismically active regions, where permanent seismotectonic process is accompanied by stronger deformation of the rocks.The atmospheric electric field and the high fre quency geoacoustic emission are measured in air near the ground and in the surface rocks. The link between disturbances of these geophysical fields various in ori gins is found in Kamchatka at calm weather free of interfered meteofactors. This link is manifested in a baylike decrease in the gradient of potential V' of the electric field (up to the change of the sign) under a sharp and significant increase in the acoustic pressure P S in the kHz frequency range. Such disturbances of V ' and P S were registered in seismically calm periods and during the final stage prior to the earthquake, which indicates their seismotectonic origin [2,3]. The disturbances of the high frequency geoacoustic emis sion prior to the earthquakes are related to active deformation of the subsurface sedimentary rocks at the measurement point [4]. Synchronous disturbances of V' and P S are registered at increase in the velocity of extension of these rocks, the deformation of which was two orders of magnitude higher than the tidal ones [5].The reason for synchronous disturbances of the atmospheric electric field and the high frequency geoacoustic emission in the seismoactive region dur ing calm weather is unclear. It is important for under standing the lithospheric effect on the atmosphere during the seismotectonic process and also the response of the electricity of the ground atmospheric layer. Below we explain the reasons for the synchro nous origin of these disturbances.In good weather, in spite of the electrode effect, a negative electric charge may originate in the air layer from decimeters to a few meters thick near the ground [6][7][8]. The average density of this charge is about -700 pC/m 3 [9], and the highest density may attain -1200 [10] and even -3200 pC/m 3 [11], which is comparable with that of the space charge in stormy clouds (300-3000 pC/m 3 ) [12]. The normal atmo spheric electric field decreases near such a strong neg ative charge or even changes its sign [10,11]. These values, however, are measured in aseismic regions. In Kamchatka, a negative space charge was recorded prior to an earthquake with magnitude 6.0 at a dis Abstract-The atmospheric electric field, the geoacoustic emission at frequencies of 0.7-2.0 kHz at three points, the volumetric activity of radon and thoron in the surface ground layer, the atmospheric pressure, the velocity of wind, and the intensity of rain were synchronously measured from August 27 to October 17, 2012, at the interception zone of various faults 41...

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.