S. V. Yakovenko

Internal marine waves and atmospheric depressions

This work describes the results of processing experimental data during synchronous registration of the crust deformations and oscillations of atmospheric and hydrospheric pressures. It was found that internal marine waves with a frequency range from 5 to 20 min are mainly generated by atmospheric disturbances, whose variations are absolutely identical to those of hydrospheric pressure in the shelf zone of the Sea of Japan.

Seismoacoustic Hydrophysical Complex for Monitoring the Atmosphere–Hydrosphere–Lithosphere System

The seismoacoustic hydrophysical complex intended for investigation of the interaction of geospheres wave fields in a frequency range from 1 μHz to 1 Hz is described. The complex consists of a shore-based system of laser strain meters, laser nanobarograph, bottom station with a hydrophone and a temperature-sensitive element, weather station, and seismoacoustic radiator. The use of modern laser-interferometry methods provided a deformation sensitivity of ∼10–10 and an atmospheric-pressure sensitivity of 10 mPa.

Recording of deformation anomaly of a tsunamigenous earthquake using a laser strainmeter

A deformation anomaly with a size of approximately 59.3 µ m caused by a tsunamigenous earthquake on December 26, 2004, was detected using a 52.5-m horizontal laser strainmeter of the unequal arm type set in Primorskii Krai of Russia. It was possible to predict a powerful tsunami wave based on the size of the deformation anomaly, which reached the strainmeter location region from the earthquake epicenter in 19 min 54 s.

Loading effect of sea level variations on the Earth’s crust

Different experimental studies in any of the com ponents of the atmosphere–hydrosphere–lithosphere transitional zone should take into account the possible erroneous interpretation of the results obtained due to lack of information about the studied processes in other geospheres. While the influence of atmospheric processes on processes in the hydrosphere is more or less well studied, the loading effect of hydrospheric processes on the level of crustal deformations is unknown, because of the uncertain structure of the Earth’s crust and because the way in which hydro spheric processes affect the Earth’s crust is almost unknown. Of course, it is known that wind driven sea waves generate microseisms of the respective periods in the crust during interacting between waves and the seafloor—it was noted as early as the 1960s by K. Has selmann [1].

A hydrophysical laser-interference complex

An upgraded laser measurer of hydrosphere pressure variations is described. By mounting new pressure and temperature sensors and optimizing the design of the submersible instrument, it has become possible to considerably increase the measurement accuracy of amplitude−frequency characteristic describing variations in the pressure, aqueous medium temperature, and wave amplitudes at the sea surface in the infrasonic and audio ranges and to correct plotted time dependences of the pressure variations in view of the variations in the interferometer and outboard water temperatures. For long-term (up to 40 h) self-contained operation of the complex to be guaranteed, a versatile floating container has been developed. This container is equipped with high-power batteries and data acquisition systems receiving information from the sensors and can be joined to a hermetically sealed connector of the complex instead of the cable line used for communication between the complex and coast equipment.

Dynamics of wind waves during propagation over a shelf of decreasing depth

A laser meter of pressure variation in the hydro sphere [1, 2] and a mobile laser meter of pressure vari ations in the hydrosphere [3] were used as the laser interference receiving systems. They were included in the laser interference hardware–software complex [4, 5] deployed at different depths in Vityaz Bay of Peter the Great Gulf in the Sea of Japan along the direction of wind wave propagation (Fig. 1). The laser meter of pressure variation in the hydrosphere was deployed at a depth of 11.8 m, and the mobile laser meter of pres sure variations in the hydrosphere was set at a depth of 4.5 m. The distance between the instruments was 96 m. The information from these laser interference systems was transmitted by cable lines to the coastal station and recorded in the data bank with a sampling fre quency of 500 Hz. Later, these experimental data were processed using a specially developed programming package software Deformograf, which applied differ ent methods of obtaining spectral and statistical esti mates.

A hydroacoustic system that radiates at frequencies of 19−26 Hz

A radiating hydroacoustic system intended to generate harmonic and phase-shifted hydroacoustic signals in the frequency band of 1 Hz with a center frequency in the range of 19−26 Hz is described. The maximum change in the radiator volume may be as large as 0.0123 m3, which corresponds to a radiated acoustic power of 1000 W at a frequency of 20 Hz in the boundless water space. The prospects of using the system for carrying out research are demonstrated via the results of its testing on the shelf of the Sea of Japan.

Interaction of low-frequency hydroacoustic waves with wind sea waves

On the basis of experimental data on hydrospheric pressure variations, obtained with the use of a laser hydrophone and laser gauge of hydrospheric pressure variations, while hydroacoustic radiators were running, generating hydroacoustic waves at frequencies of about 32, 245, and 421 Hz in water, it was established that there is no modulating action of wind sea waves on the propagating hydroacoustic signals along the “radiator-receiver” trace, within the limits of experimental error and the processing methods used.