Seismic Acoustic Signals Research Articles

Methodical principles of experimental-analytical research into the influence of pre-drilled wells on the intensity of gas-dynamic phenomena manifestations

Purpose.The research aims to substantiate the general provisions on coordination of the experimental-analytical research results of the influence of pre-drilled wells on the intensity of gas-dynamic phenomena manifestations (using the example of the mining-geological conditions of the phenomena at the PJSC Mine Administration Pokrovske, Ukraine). Methods. The research uses an integrated methodology consisting of indirect experimental methods for studying the adjacent rock mass state and tendencies. Findings. It has been proven that indirect experimental indicators of the rock mass state around the tunneling face are related to the peculiarities of the distribution of its stress-strain state components. Based on this research, the well lengths of up to 10-15 m has been determined to effectively and safely de-stress the rock mass. The experimental research validity is confirmed by conducted computational experiments, in the course of which the dependence of the propagation parameters of the stress-strain state component concentrations on the degree of hardness of the lithotypes is revealed, and a geomechanical substantiation to the tendencies of propagation of rock pressure anomalies near stoping and tunneling faces is given. The new knowledge obtained is the basis for creating a method for calculating rational parameters for the location of de-stressing pre-drilled wells. Originality. An objective assessment of the degree of adequacy and reliability of the computational experiment results has been made under the condition of using a new geomechanical model with mine studies of seismic-acoustic signal parameters and the initial gas release velocity. The main tendencies of vertical σу, horizontal σх and σz, as well as stress intensity propagation have been identified. The obtained results of exploring the bottom-hole mass are aimed at substantiating the parameters of anti-outburst measures for all preparatory mine workings. Practical implications. The conducted research is implemented in creation of a calculation method and recommendations for the selection of rational parameters for the location of de-stressing pre-drilled wells for the purpose of weakening the rock mass, surrounding the tunneling face, and reducing the probability of gas-dynamic phenomena occurrence due to the controlled weakening of adjacent rocks.

Feature Extraction of a Non-Stationary Seismic–Acoustic Signal Using a High-Resolution Dyadic Spectrogram

Using a novel mathematical tool called the Te-gram, researchers analyzed the energy distribution of frequency components in the scale–frequency plane. Through this analysis, a frequency band of approximately 12 Hz is identified, which can be isolated without distorting its constituent frequencies. This band, along with others, remained inseparable through conventional time–frequency analysis methods. The Te-gram successfully addresses this knowledge gap, providing multi-sensitivity in the frequency domain and effectively attenuating cross-term energy. The Daubechies 45 wavelet function was employed due to its exceptional 150 dB attenuation in the rejection band. The validation process encompassed three stages: pre-, during-, and post-seismic activity. The utilized signal corresponds to the 19 September 2017 earthquake, occurring between the states of Morelos and Puebla, Mexico. The results showcased the impressive ability of the Te-gram to surpass expectations in terms of sensitivity and energy distribution within the frequency domain. The Te-gram outperformed the procedures documented in the existing literature. On the other hand, the results show a frequency band between 0.7 Hz and 1.75 Hz, which is named the planet Earth noise.

Features of Propagation and Transformation of Low-Frequency Hydroacoustic Signals on a Shelf of Decreasing Depth

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.

Earthquake Time Prediction using CatBoost and SVR

Seismic tremors everywhere throughout the globe have been a noteworthy reason for decimation and death toll and property. The following context expects to recognize earthquakes at a beginning time utilizing AI. This will help individuals and salvage groups to make their errand simpler. The information in this manner comprises of these seismic acoustic signals and the time of failure. The model is then prepared utilizing the CatBoost model and the utilization of Support Vector Machines. This will help foresee the time at which a Seismic tremor may happen. CatBoost Regression Algorithm gives a Mean Absolute Error of about 1.860. The Cross Validation (CV) Score for the Support Vector Machine (SVM) approach is -2.1651. The datasets metrics are not reliable on any outer parameter in this manner the variety of exactness is constrained, and high accuracy is accomplished.

Detection of Unobserved Ground Targets by Use of Seismic Location Stations

The detection method of moving unobserved ground military heavy trucks is considered in paper. The 3D coordinates detection set and the seismic location method are used in our study. The computational algorithm of determination of the bearing angle and distance to unobserved ground target are presented, the computational uncertainties are estimated. The triangular form of 3D detectors in one seismic location cell is offered. It allows minimizing distance and angle uncertainties in target direction. To improve the detection effectiveness, the optimal geometry disposition of 3D detectors in seismic location cells is determined. The offered method is effective in case of terrain relief where seismic-acoustic signal is propagated by approximately straight line. Therefore, this method can be applied only to homogenous medium, for example, to mountainous, solid rocky soil.

Алгоритм идентификации и определения курса движущейся ненаблюдаемой бронетехники

The article considers a mathematical formalization of the task of identification of heavy armoured vehicles which secretly move in mountain terrain. A n analysis of seismic acoustic signals formed in solid soil when vehicles move, helicopters and aircrafts flight is conducted. An algorithm of determination of the courseand coordinates of armoured vehicle movement is developed.

Features of the use of an automated seismic acoustic complex by a combined method of detection objects

The article deals with the analysis of existing intelligence and signaling devices (ISD) using principles based on the use of modern seismic acoustic sensors to detect the coordinates of moving and immobile objects. The advantages and disadvantages of the seismic and acoustic detection principle, as separate and independent methods, as well as the advantages of using the combined detection method, are revealed. Complex combined use of acoustic, seismic or seismic acoustic sensors instead of just one typical element significantly extends the areas of use of complex groups of these devices, which accordingly reduces the influence of natural properties on processes for qualitative and accurate measurement results. The results of automatic processing of real seismic acoustic records from the «Little Girls» site were obtained using the method of mathematical processing of a seismic, acoustic, or seismic acoustic signal based on the well-known method for allocating primary wave inputs based on the use of the LTA/STA method (Long Time Amplitude/Short Time Amplitude method). According to the results of these studies, it has been shown that this automated approach to data flow processing using the LTA/STA method allows accurately determining the time of the arrival of waves of a seismic acoustic signal of different origins. The preliminary statistical estimation of the difference between the values of the calculated coordinates of the source of the seismic acoustic signal and its real coordinates has been carried out. This basic part of the research shows that there is a possible choice of optimal value of the rate of propagation of the seismic acoustic signal, the value of which can be used in conducting further research at landfills, quarries or mines. Preliminary conclusions from the conducted research, which show that the simultaneous use of general principles for seismic and acoustic signals to detect the origin of these signals greatly improves the efficiency of these methods and tools for detecting the coordinates of moving objects or man-caused phenomena, and also improves the accuracy of the determination of dynamics changes in the values of the coordinates of military objects and other dangerous processes that they generate.

The impact of seismic air gun exposure on the haemolymph physiology and nutritional condition of spiny lobster, Jasus edwardsii

There is a critical knowledge gap regarding the impacts of seismic air gun signals on the physiology of adult crustaceans. We conducted four controlled field experiments to examine the impact of seismic acoustic signals on spiny lobster, Jasus edwardsii. Seismic air gun exposure suppressed total haemocyte count (THC) for up to 120days post-exposure, suggesting a chronic negative impact of immune competency. THC levels after 365days post-exposure, were elevated two fold, potentially indicating an immune response to infection. Haemolymph refractive index was reduced after 120days post exposure in one experiment, suggesting a chronic impairment of nutritional condition. There was no effect of air gun exposure on 24 haemolymph biochemical parameters, hepatopancreas index or survival. Collectively these results indicate that the biochemical haematological homeostasis of J. edwardsii is reasonably resilient to seismic acoustic signals, however, air gun exposure may negatively influence the lobster's nutritional condition and immunological capacity.

Intelligent Seismic-Acoustic System for Identifying the Location of the Areas of an Expected Earthquake

A brief overview of the state-of-the-art in the field of earthquake study and forecasting is presented in this paper. We analyze the principles of the methods of determining the coordinates of earthquake focuses by means of ground seismic stations. We demonstrate that those methods cannot be used in the system for monitoring of the beginning of the earthquake preparation process (in the network of RNM ASP stations). As we know, the earthquake preparation process is accompanied by spreading noisy seismic-acoustic signals. Theoretically, the system for monitoring of the beginning of the earthquake preparation process is based on the technologies for seismic-acoustic signal processing-Robust Noise Monitoring (RNM). Noise characteristics determined by RNM technologies indicate the beginning of anomalous seismic processes (ASP) and, consequently, the possibility of ASP monitoring. Considering that the seismic-acoustic signal can be represented as the sum of the useful signal and noise, we present the technologies for determining noise characteristics. It is demonstrated in the paper that a change in the estimate of the cross-correlation function between the useful signal and the noise, noise variance and the value of noise correlation determine the beginning of ASP. One RNM ASP station determines the beginning of ASP within a radius of about 500 km. Determining the location of an expected earthquake requires a network of RNM ASP stations. We analyze the results of noise technology-based monitoring of anomalous seismic processes performed from July 2010 to June 2015 on nine seismic-acoustic stations built at the head of 10 m, 200 m, 300 m and 1400 - 5000 m deep wells. Based on the results of the experimental data obtained in the period covering over three years, an intelligent system has been built, which allows for identifying the location of the zone of an earthquake, using the combinations of time of change in the estimate of the correlation function between the useful signal and the noise of the seismic-acoustic information received from different stations 10 - 20 hours before the earthquake. In the long term, the system can be used by seismologists as a tool for determining the location of the zone of an expected earthquake.

Propagation of low-frequency waves over Cape Schultz

The paper presents the results of field and numerical studies of the propagation features of lowfrequency pulse and tonal seismic acoustic signals of tracks intersecting Cape Schultz. Measurements were conducted using digital radiohydroacoustic buoys, a pulsed pneumoemitter suspended from the side of a motorboat, and a shorebased electronic resonance seismic emitter in Vityaz Bay in the Sea of Japan.

System of robust noise monitoring of anomalous seismic processes

Robust noise technology is presented for the analysis of seismic-acoustic signals, which allows the use of noise in the signal as a carrier of information at the start of anomalous seismic processes preceding earthquakes. A station has been built based on this technology, which receives seismic-acoustic noises from the deep strata of the earth by means of 3–6km deep steel bores suspended in oil wells, performing monitoring of the beginning of the latent period of earthquake formation. Experiments carried out at stations at Qum Island in the Caspian Sea since 01.05.2010 and in the town of Shirvan in the south of Azerbaijan since 20.11.2011 have proven the reliability and adequacy of results when monitoring and identifying earthquakes within a radius of 300–500km, 10–15h before the earthquakes are detected by standard seismic stations.

Technologies for noise monitoring of abnormal seismic processes

Robust noise technologies for analyzing a seismic acoustic signal that allow using its noise as a carrier of information at the beginning of abnormal seismic processes preceding an earthquake are proposed. A station which receives seismic acoustic signals from the deep strata of the earth with the help of 3–6 km-deep steel bores of dormant oil wells has been designed based on this technology. It monitors the beginning of the latent period of the earthquake development. The experiments carried out at these stations on Qum Island in the Caspian Sea since May 1, 2010 and in the town of Shirvan in the southern region of Azerbaijan since November 20, 2011 confirmed the reliability and validity of the monitoring results and identification of the earthquake in the radius of 300–500 km with a 10–15 h lead as compared to conventional seismic stations.

A self-contained acoustic station with a digital radiotelemetry channel for monitoring seismic acoustic signals on the shelf

The Shelf-09 self-contained acoustic station has been developed at the Il’ichev Pacific Oceanological Institute for long-term (up to 1 month) stationary measurements (on the shelf) of acoustic pressures varying in a 2- to 15 000-Hz band. The station is intended for monitoring of characteristics of seismic acoustic signals and noises produced by a seismic survey ship operating on the shelf at the boundaries of the nearest known range of rare marine animals so as to exclude possible anthropogenic influence on them. To arrange online monitoring of industrial noises and pulse seismic acoustic signals, the acoustic data measured in a 2- to 2000-Hz band are transmitted to a coastal post or ship via a digital VHF radiotelemetry channel. The Shelf-09 station has successfully passed tests under laboratory and field conditions.

Hydro-seismic-acoustical monitoring of submarine earthquakes preparation: observations and analysis

Abstract. The results of laboratory experiments on rock sample destruction and the observation data obtained from several series of the hydro-acoustic observations in which the researchers succeeded to register the signals in the critical stage of the earthquake (EQ) preparation were compared. According to theoretical research (Alekseev et al., 2001) two distinct dilatant zones occur in the EQ preparation stage. The first one is located around the source and the second one represents the near-surface dilatant zone. Only high-frequency seismic-acoustic signals (SAS) radiated from the near-surface dilatant zone do not attenuate completely on the passage through a solid medium. Parameters of the SAS such as the source depth under the ocean floor, frequency maximum and the signal power level were estimated. It was shown that the critical stage of the EQ preparation continues several tens hours and this process has a hierarchical nature. At first the micro-ruptures are formed over a large area. Then the high frequency radiation begins to decrease, the SAS emission area begins to shrink and the micro-earthquakes occur in the area surrounding the epicenter. The obtained results are in close agreement with the theoretical conception about the evolution of the SAS in the surface dilatant zone and with the results of laboratory experiments.

Determination of the Acoustic Coupling Factor of Biot's Theory of Elasticity, Using in situ Seismic Measurements

Besides other elastic, petrophysical, and hydrophysical parameters, the acoustic coupling factor (coupling factor or structure factor, s ) is a critical micro-geometrical parameter in the Biot's theory of elasticity. The coupling factor exerts a specific influence on the mechanisms of propagation and attenuation of vibrations (seismic waves and acoustic signals) in porous media. It is a measure of the internal structure (geometry and shape of pores and pore tubes) of a porous medium, and thus it is a good indicator of the degree of coupling between pore fluid and solid grains. It is unity for no coupling and infinity for perfect coupling. In this study, the coupling factor is obtained for surface soils and shallow sediments, using compressional wave velocity ( x p ) determined from in situ seismic refraction measurements. The investigated soils and underlying sediments (aeration zone and aquifer) exhibit a general s range of 1.22-3.19 (average = 1.82), corresponding to a general x f range of 134-2060 m/s (average = 1134 m/s). The s values are correlated to the bulk modulus-shear modulus ratio (K/ w ) and the porosity (φ). A direct linear correlation between s and K/ w and an inverse polynomial correlation between s and φ are obtained, with coefficients of correlation of 0.91 and 0.98, respectively. Also, various items related to the coupling factor, Biot's theory, attenuation mechanisms, fast and slow compressional waves (first and second kinds), and shear waves are discussed.

Seismic-acoustic studies of dynamic phenomena in the production unit “Mechekugol'”

The authors study the dynamic phenomena and sudden outbursts in the production unit Mecheugol in the mine using Danish seismic-acoustic instruments. Acoustic measurements are made of vibration phenomena in the mine and the recording of information in analog form in four channels independent of each other is performed. The analog signals that are recorded are estimated and analyzed. This seismic-acoustic system is used for studying vibration phenomena in specimens under laboratory conditions and studying dynamic phenomena in the mine over a wide frequency range is accomplished. Seismic-acoustic observations are made of induced rock bursts and spontaneous seismic-acoustic signals are examined.