This paper describes the results of monitoring wave processes in the geospheres using laser interference instruments, a weather station, a seismometer, and other measuring devices. Processing in situ data revealed general patterns in seismic events and variations in the hydrosphere and atmospheric pressure. Laser strainmeters and a seismometer were used to identify natural and anthropogenic seismic activity. A laser nanobarograph and strainmeters allowed us to detect baro-deformation interactions. Processing data from supersensitive detectors of hydrosphere pressure variations, a tide gauge, and temperature sensors revealed regional features of marine wave processes.

This work is devoted to an experiment studying the regularities of the propagation of hydroacoustic low-frequency signals in the conditions of the sea at intermediate depth and deep in terms of their transformation into vibrations in the upper layer of the Earth’s crust. This experiment belongs to the field of acoustic tomography and is aimed at solving the problems of non-contact methods for studying the geological structure of the shelf areas of the World Ocean. The novelty and uniqueness of the work lies in the use of a harmonic low-frequency hydroacoustic signal with a frequency of 22 Hz of high power, capable of creating Rayleigh surface waves at the “water–bottom” interface. The surface waves propagating at the bottom are registered by a coastal laser-interference measuring system capable of recording deformations in the upper crustal layer with an accuracy of 0.01 nm. The experimental results showed that the radiated hydroacoustic energy is not localized in the liquid half-space and propagates predominantly according to the law close to spherical divergence, even when the shelf depth is comparable to the wavelength of the radiated signal.

Based on the field data of laser interference devices obtained on the shelf of the Sea of Japan, the interaction of internal sea waves with the bottom and the transfer of energy from the sea wave to the seismic acoustic wave were studied. It has been established that when internal waves move from the depth dump to the surf zone, they transform, and their period decreases. When the energy of the internal wave is transformed into elastic bottom vibrations, the flow density is estimated to spread evenly over a shelf about 30 km wide. Taking into account the maximum amplitudes of elastic bottom vibrations caused by offshore internal waves, the density of the seismic energy flux will increase by 2–3 orders of magnitude and will be comparable to the density of the seismic energy flux caused by surface sea waves.

The paper describes a planetary laser interferometric seismoacoustic observatory consisting of six stationary unequal arm laser strainmeters. Based on the triangulation method, the fundamentals of direction finding of various infrasound disturbances at any planetary distance have been developed. The authors show that in addition to determining locations of the occurrence of the recorded disturbance, using data from spatially separated laser strainmeters, it is possible to determine the nature of these signals’ divergence and, also, the loss of their energy in the propagation medium. The creation of the planetary laser interferometric seismoacoustic observatory, consisting of five stationary single-coordinate laser strainmeters and one two-coordinate laser strainmeter, united into a single measuring network with an accurate time clock TRIMBLE 5700 that is capable of recording displacements on their bases with an accuracy of 10 pm in the frequency range from 0 (conventionally) to 1000 Hz and two auxiliary laser strainmeters, will allow us to determine, at any planetary distance, the primary source of deformation infrasound disturbances with primary amplitudes from 100 nm.

During the propagation of the Hinnamnor typhoon from September 5 to 6, 2022, swell waves were recorded that arrived at the recording point 20 h before the typhoon entered the Sea of Japan. While analyzing the field data of the laser meter of fluid pressure variation, it was possible to calculate the area of the formation of the main group of swell waves generated by the propagating typhoon and to localize the region of generation of forerunner waves and also to describe the mechanisms of their formation and propagation.

An analysis of the behavior of the infra-gravitational sea wave revealed nonlinear hydrophysical disturbance of the “rogue waves” type. This disturbance is associated with transformation of sea waves when they move along a coastal marine area of decreasing depth, and with interaction with wind waves. These conclusions are confirmed through analysis of in situ data of the laser interference pressure meter of the hydrosphere in this paper and previous works. Full-scale data were obtained on the shelf of the Sea of Japan. During processing of in situ data, we focused on sea waves with periods ranging from 1 to 10 min.

Transformations of bottom pressure variations generated by infragravity waves into displacements of the upper layer of the Earth’s crust have been quantitatively assessed based on the experimental data obtained with a laser meter for hydrospheric pressure variations and two laser strainmeters. The relationship between the coefficient of bottom pressure transformation into elastic vibrations of the Earth’s crust and the infragravity wave period has been determined.

On the basis of experimental data from laser strainmeters, a laser nanobarograph, and a laser meter of hydrosphere pressure variations, we studied inter-geosphere interaction in microseismic range (2–20 s) and in minute range (4–17 min). We established general patterns of transformation of the Earth’s crust upper layer oscillations into atmospheric oscillations, and atmospheric oscillations—into oscillations of the Earth’s crust upper layer in the specified ranges. Besides, we show that transformation coefficient has seasonal dependence, associated with different elastic characteristics of the Earth’s crust upper layer in winter and summer due to negative winter temperatures and high positive summer temperatures, and also different moisture saturation of the soils.

В работе подтверждена сильная взаимосвязь пространственных свойств инфрагравитационных волн и характеристик волн зыби. Показано, что уровень энергии инфрагравитационных волн зависит от географических условий и местных особенностей. При обработке большого массива данных по вариациям гидросферного давления, полученных в ТОИ ДВО РАН с помощью лазерно-интерференционных донных измерительных систем, обнаружено, что поверхностные ветровые волны и зыбь в окрестностях мыса Шульца Японского моря усиливают амплитуды инфрагравитационных волн с периодами от 20 до 300 с. То есть, установлено соответствие возрастания амплитуды ветровых волн и зыби возрастанию амплитуды инфрагравитационных волн. Замечено, что это правило работает и в обратном порядке, т.е. снижение амплитуды ветровых волн и зыби соответствует снижению амплитуды инфрагравитационных волн. При этом рост амплитуды инфрагравитационных волн сопровождается возрастанием периода ветрового волнения. Данные инфрагравитационные волны распространяются в виде волновых цугов, границы которых практически не меняются со временем, при этом период отдельных волн внутри цугов может меняться, однако характер и параметры этих изменений не зависят от характеристик породивших их волн. В то же время обнаружено, что инфрагравитационные волны подвержены изменению своей спектральной структуры в случае влияния на них местных колебательных процессов. Так, в бухте Витязь инфрагравитационные волны имеют в спектре боковые максимумы, обусловленные модуляционным воздействием сейшевого колебательного процесса бухты. Периоды инфрагравитационных и ветровых волн, регистрируемых в бухте Витязь, могут быть промодулированы также приливно-отливными колебаниями, характеристики которых, очевидно, зависят от местных условий. Отмечено также, что спектральные максимумы, регистрируемых в бухте инфрагравитационных волн, имеют дискретную структуру, обусловленную модуляционным воздействием более низкочастотных волн. The work confirms the strong relationship between the spatial properties of infragravitational waves and the characteristics of swell waves. It is shown that the energy level of infragravitational waves depends on geographical conditions and local features. It was found that surface wind waves and swell in the vicinity of Cape Schulz in the Sea of Japan enhance the amplitudes of infragravitational waves with periods from 20 to 300 s. That is, the correspondence between the increase in the amplitude of wind waves and swell and the increase in the amplitude of infragravitational waves has been established. In this case, the increase in the amplitude of infragravitational waves is accompanied by an increase in the period of wind waves. These infragravitational waves propagate in the form of wave trains, the boundaries of which practically do not change with time, while the period of individual waves inside the trains can change, however, the nature and parameters of these changes do not depend on the characteristics of the waves that generated them. At the same time, it was found that infragravitational waves are subject to a change in their spectral structure if they are affected by local oscillatory processes. Thus, in the Vityaz Bay, infragravitational waves have side maxima in the spectrum, due to the modulation effect of the seiche oscillatory process of the bay. The periods of infragravitational and wind waves recorded in Vityaz Bay can also be modulated by tidal oscillations, the characteristics of which obviously depend on local conditions.

In this paper, we analyzed the results of experimental data processing in the study of regularities of propagation and transformation of low-frequency harmonic signals at the boundary of the “sea−land−sea” system. Harmonic signals at a carrier frequency of 33 Hz were generated by a low-frequency hydroacoustic radiator in Vityaz Bay. Then, they passed along the shelf of decreasing depth, transformed into seismoacoustic signals of the upper layer of the Earth’s crust and the bedrocks of Shultz Cape and excited hydroacoustic signals at the corresponding frequency in the shelf waters in the open part of the Sea of Japan. When processing the experiment results, we obtained the vertical distributions of the pressure field, caused by an acoustic low-frequency signal passing through the upper layer of the Earth’s crust. We presented the distributions of hydroacoustic and seismoacoustic energies. The obtained experimental data were compared with the simulations by the model, developed strictly according to the experiment scheme and the geological structure of the area. In the discussion of the obtained results, we explained a probable mechanism of acoustic energy propagation and the nature of the vertical distributions of the pressure field formation.

Рассмотрены два метода пеленгования геосферных источников колебаний и волн инфразвукового и низкочастотного звукового диапазонов лазерными деформографами. Первый метод основан на предположении, что регистрируемые волновые возмущения относятся к поверхностным волнам рэлеевского типа. В этом случае используется двухкооринатный лазерный деформограф, состоящий из рядом стоящих однокоординатных лазерных деформографов с взаимно-­перпендикулярными измерительными плечами. Во втором случае используется триангуляционный метод. В этом методе применяются минимум три пространственно-­разнесенных лазерных деформографа.

This paper describes a method for identifying modulation effects caused by the interaction of waves with different frequencies based on regression analysis. We present examples of its application on experimental data obtained using high-precision laser interference instruments. Using this method, we illustrate and describe the nonlinearity of the change in the period of wind waves that are associated with wave processes of lower frequencies—12- and 24-h tides and seiches. Based on data analysis, we present several basic types of modulation that are characteristic of the interaction of wind and swell waves on seiche oscillations, with the help of which we can explain some peculiarities of change in the process spectrum of these waves.

By the analysis of the experimental data and model calculations, features of the propagation of hydroacoustic signals over a shelf of decreasing depth generated by a low-frequency hydroacoustic emitter at a frequency of 22 Hz and their transformations at the “water–bottom” interface into the Rayleigh waves recorded by a coastal laser strainmeter are studied. Energy estimates for the propagating hydroacoustic signals are presented at different points on the shelf; and such estimates for the transformed seismic–acoustic signals are obtained at the location of a laser strainmeter in the Earth’s crust.

The dynamic features of shelf infra-gravity sea waves and their relation to the main parameters of gravity sea waves are studied using experimental data obtained from a laser meter of hydrosphere pressure variations installed on the shelf of the Sea of Japan at a depth of 27 m.

In research into various hydrophysical and hydroacoustic wave processes, it is extremely important to know the regularities of their propagation in the sea at decreasing depths, especially in the shelf areas, and also to know the regularities of their transformation into seismoacoustic processes in the earth crust. In the course of the processing and analysis of the experimental data of our complex experiment, in this paper we investigate these regularities. In our experiment, we used a low-frequency hydroacoustic transmitter that generated harmonic oscillations at the frequency of 22 Hz and received hydroacoustic systems with a shore laser strainmeter. It was established that hydroacoustic waves, propagating at the shelf of decreasing depth, transform into seismoacoustic waves at the depth of the sea equal to or less than a half-length of the hydroacoustic wave. A comparison of the results of this work with earlier-obtained results allows us to state that such regularities should be inherent to all hydrophysical and hydroacoustic processes.

При исследовании различных гидрофизических и гидроакустических волновых процессов крайне важно знать закономерности их распространения в море убывающей глубины, особенно в шельфовых областях, а также закономерности их трансформации в сейсмоакустические процессы земной коры. В ходе обработки и анализа экспериментальных данных комплексного эксперимента в данной статье исследуются эти закономерности. В эксперименте использовались низкочастотный гидроакустический излучатель, генерирующий гармонические колебания на частоте 22 Гц, приемные гидроакустические системы и береговой лазерный деформограф. Установлено, что гидроакустические волны, распространяющиеся по шельфу убывающей глубины, трансформируются в сейсмоакустические волны при глубинах моря, равных или меньше половины гидроакустической длины волны. Сравнение результатов данной статьи с ранее полученными результатами позволило утверждать, что такие закономерности должны быть присущи всем гидрофизическим и гидроакустическим процессам. When studying the various hydrophysical and hydroacoustic wave processes, it is extremely important to know the regularities of their propagation in the sea of decreasing depth, especially in the shelf areas, as well as the regularities of their transformation into seismoacoustic processes of the earth’s crust. In the course of processing and analyzing the experimental data of the complex experiment, these regularities are investigated in this article. The experiment used a low- frequency hydroacoustic emitter generating harmonic oscillations at a frequency of 22 Hz, receiving hydroacoustic systems and a coastal laser strainmeter. It has been established that hydroacoustic waves propagating along a shelf of decreasing depth are transformed into seismoacoustic waves at sea depths equal to less than half of the hydroacoustic wavelength. Comparison of the results of this article with previously obtained results made it possible to assert that such regularities should be inherent in all hydrophysical and hydroacoustic processes.

Features of the tomography of the marine crust are described, based on the use of coastal laser strainmeters and broadband low-frequency underwater acoustic projectors. This approach is useful in studying the structure and composition of the marine crust in shelf areas, including ones covered with ice without destroying it. Numerous experimental studies have established that at sea depths equal to or less than half the length of a hydroacoustic wave generated by low-frequency underwater acoustic projectors, the hydroacoustic energy is mainly transformed into Rayleigh-type surface waves that radiate through the bottom on the hydroacoustic source–coast path.