Seismic Emission Research Articles

Intermediate States between Statics and Dynamics and Seismic Emission in Granular Media

Intermediate States between Statics and Dynamics and Seismic Emission in Granular Media

Seismic Features Predict Ground Motions During Repeating Caldera Collapse Sequence

AbstractApplying machine learning to continuous acoustic emissions, signals previously deemed noise, from laboratory faults and slowly slipping subduction‐zone faults, demonstrates hidden signatures are emitted that describe physical details, including fault displacement and friction. However, no evidence currently exists to demonstrate that similar hidden signals occur during seismogenic stick‐slip on earthquake faults—the damaging earthquakes of most societal interest. We show that continuous seismic emissions emitted during the 2018 multi‐month caldera collapse sequence at the Kı̄lauea volcano in Hawai'i contain hidden signatures characterizing the earthquake cycle. Multi‐spectral data features extracted from 30 s intervals of the continuous seismic emission are used to train a gradient boosted tree regression model to predict the GNSS‐derived contemporaneous surface displacement and time‐to‐failure of the upcoming collapse event. This striking result suggests that at least some faults emit such signals and provide a potential path to characterizing the instantaneous and future behavior of earthquake faults.

INTERMEDIATE STATES BETWEEN STATICS AND DYNAMICS AND SEISMIC EMISSION IN GRANULAR MEDIA

Seismic emission is the spontaneous emission of waves in a porous or fractured medium. There is still no explanation for the dependence of these phenomena on the parameters of the medium and the structure of the pore space, as well as for the transition from slow to fast movements. The paper proposes a description of the transition process from statics to dynamics using a model of structured continuum with an internal structure. The most important parameters of the model are the specific surface area and porosity of the medium. The reason for the emission is that the forces caused by internal stresses are only on average equal to zero over a representative volume, being different at each point of the medium. It is shown that the model of a structured continuum predicts the emission of waves under static load and gives an estimate of the emitted oscillation periods. In this case, the characteristic oscillation periods depend neither on the characteristic time of destruction of particles, nor on the loading time.

Forecast of oil and gas reservoirs of the Sea of Okhotsk based on interpretation processing of seismic material

Background. This article analyses the results of geological and geophysical studies conducted in the Okhotsk Sea area with the purpose of developing methods for processing seismic information in combination with other data to solve the problems of forecasting hydrocarbon deposits.Aim. Solving problems of forecasting hydrocarbon deposits through the development of a structural and technological scheme for prospecting and evaluation of a geological and geophysical model to identify images of oil and gas deposits.Materials and methods. The research methodology included selection of the location of points for simulating “vertical wells” in order to analyze the geodynamics of the medium; multiplex parametric transformations of wave fields taking into account diagnostic significant attributes and building a multiparametric cluster; selection of oil and gas deposits; formation of images of oil and gas deposits; local forecast of improved reservoir properties and saturation; refinement of the geometry of target surfaces with forecast data in actual points (vertical wells); forecast of the area of target surfaces; spatial mapping of the largest hydrocarbon deposits.Results. Forecasting of oil and gas prospects in the Okhotsk Sea in areas where there is no deep drilling can be carried out using the following technologies: detailing the structural and tectonic structure of hydrocarbon traps; multi-feature prediction of hydrocarbon deposits; decomposition of the dispersion of the wave field; low-frequency resonance of seismic emission geodynamic noise; selection of oil and gas-containing objects.

Characterization and response of three TNT equivalent materials in subsurface explosions

AbstractEnergetic compositions utilized for inducing seismic responses are often referred to in terms of their TNT equivalent, a metric which is often misused because observations of interest are not often understood with respect to explosive characteristics. In this investigation, we characterize three energetic compositions used to elicit seismic responses in a highly instrumented testbed to further our understanding of subsurface TNT equivalence. Three different energetic sources are prepared and studied for their fidelity to thermochemically predicted detonation behavior. We present effects of subsurface detonation on subsurface rock and seismic emission as a function of energetic source material within the testbed. Field experiments were conducted using a single thermochemical yield of 5 kg using diverse sources consisting of nitromethane, ammonal, and PBXN‐5 (an HMX based plastic bonded explosive) mixtures at the Energetic Materials Research and Testing Center in Socorro, New Mexico. Relative performance of energy density‐related detonation parameters, such as detonation velocity and pressure, affect the observed response in the subsurface. Most notable, equal thermochemical yields described in terms of TNT equivalence do not correlate to equal thermochemical effects in the subsurface.

Experience of experimental recording of seismic emission of the side array during open mining of coal deposits

The article deals with issues related to the development of seismological equipment and software, in relation to the study of seismic emission as a harbinger of destructive deformations of the side of a coal quarry. Examples of recordings of typical seismic impacts are given. The filtering and event selection algorithms used in the processing of records are shown.

Acoustic and Seismic Emission in Hydraulic Fracturing of Cement Block under Loading

Acoustic and Seismic Emission in Hydraulic Fracturing of Cement Block under Loading

Analysis and Modeling of High-frequency Emission and Deep Seismic Sources of Sunquakes

Recent work published by Lindsey et al. find evidence for a deep and compact seismic source for the sunquake associated with the 2011 July 30 M9.3 flare, as well as seismic emission extending up to 10 mHz. We examine the sunquake independently, and a possible wave front is found in the 8 mHz band, though no wave front is easily discernible in the 10 mHz band. Additionally, we perform numerical simulations of seismic excitation modeled with the reported parameters and changes in the power spectra with increasing depth of the excitation source are examined. It is found that the peak frequency decreases for increasing depths, but a shallow minimum is indicated between z = 0 and z = −840 km. Analysis of the suspected wave front of the M9.3 sunquake finds that the power spectrum of the reported seismic emission is close to that of background oscillations, though with a peak frequency noticeably lower than the background peak. Additionally, it is found that the amplitude of the source estimated by Lindsey et al. is too low to produce the observed wave front.

BYSTROV VIBROSEISMIC LANDFILL OF THE GEOPHYSICAL SURVEY FEDERAL RESEARCH CENTRE RAS AS A UNIQUE FACILITY FOR THE DEVELOPMENT AND EXPERIMENTAL TESTING OF NEW GEOPHYSICAL TECHNOLOGIES

Information is presented about the Bystrov vibroseismic landfill near Novosibirsk, which houses Large-Scale Research Facilities with no analogues in the world – powerful 50–100-ton vibration sources (GRV-50, CVM-100, CV-40). The infrastructure of the landfill, the composition of the equipment, the tasks of scientific research, Russian and foreign performers of developments are described. The main research results of fundamental and practical importance are presented. One of the main tasks that the created polygon is aimed at is active vibroseismic monitoring with powerful vibrators. The repeatability and accuracy of monitoring, which is one millisecond in kinematic parameters, is shown; the existing monitoring scheme and prospects for increasing the monitoring area due to a stationary seismological network of stations are presented. An example of one of the promising fundamental developments is shown – the study of seismic emission during the excitation of a powerful low-frequency impact on the environment.

Acoustic and Seismic Emission in Hydraulic Fracturing of Cement Block under Loading

Acoustic and Seismic Emission in Hydraulic Fracturing of Cement Block under Loading

Experimental capabilities of seismic emission tomography for solving the problems of searching and exploration of deep hydrocarbon accumulations

The standard seismic prospecting has been designed to investigate thin layering at shallow depths. At depths more than 4 km the rocks are significantly compacted, change their properties and it is often impossible to trace clear horizons by reflected waves. In the crystalline basement and lower horizons of the sedimentary cover the block structure of rocks is clearly manifested. Taking this into account geological models should be developed and other predictive indicators should be used when searching for hydrocarbon accumulations. For the study of great depths more informative seismic methods are emission and transmission tomography which have been developed in detail in seismology. This article discusses prognostic indicators different from seismic prospecting and presents experimental results confirming the success of emission tomography in their detection using the example of field studies at developed hydrocarbon deposit and other geophysical objects. The range of working depths of research covers the entire crust of the Earth including the crust-mantle transition zone. Keywords: seismic emission; emission tomography; rocks; hydrocarbon deposits.

INTEGRATION POTENTIAL OF MICROSEISMIC ANALYSIS AND GEOPHYSICAL METHODS. GAS CONDENSATE FIELD CASE STUDY

This study is devoted to an analysis of microseisms registered on gas-condensate field area. Presence of seismic emission effect on a part of the area is demonstrated. A microseismic anomaly is outlined in NW part of the area and proves correct by 3 seismic CDP profiles and interpreted as a reservoir. The results of the special processing was compared to the results of a set of other geophysical methods. Correlation between the found anomaly and an anomaly found with aerogamma-specrtometry is shown. The results can be used in an integrated interpretation of geophysical data for oil and gas reservoirs of both structural as nonstructural types.

Research of the microseismicity location algorithm

In this paper, we propose the algorithm for locating microseismic events by the method of directed summation of energy envelopes over a network of stations. The algorithm is based on a back projection technology, which allows visualizing the intensity of seismic emission by layer. A comparative stability and robustness analysis of the proposed method with the method using the semblance is carried out.

Seismic Imaging of Convective Geothermal Flow Systems to Increase Well Productivity

A core feature of convective geothermal resource production is wellbore energy flow Q ~ ρC x T x V. E.g., for wellbore fluid of volume heat capacity ρC ~ 4.3MJ/m3∙oC, temperature T ~ 230oC, and volumetric flow V ~ 50L/s, wellbore heat energy production is Q~ 50MWth ~ 5MWe. Wellbore fluid flow V =2πr0φv0ℓ for open wellbore length ℓ is given in turn by the spatially variable product crustal porosity times crustal fluid velocity v ≡ φv0 at the wellbore radius r0. For a geothermal wellbore to be productive (nominal Q ~ 5MWe), locally variable bulk inflow rates v = φv0 across crustal volumes of dimension ℓ must be adequate to sustain high wellbore flows (nominal V ~ 50L/s). Wide-ranging crustal well productivity statistics show that few crustal wells flow at these rates. This is not surprising as local bulk flow ~ 10-2 m/s needed for production wellbores is decades greater than ambient bulk fluid flow ~ 10-8-10-7m/s characteristic of natural convective geothermal systems. Such rare high flow locales must be found. While existing crustal surveys generally fix resource temperatures T with nominal 500m spatial resolution, as yet no survey technique provides data to locate production-grade flow rates at nominal ℓ ~ 50m spatial resolution. In consequence, many costly unproductive wells are drilled before sites of productive local geothermal fluid bulk flow v = φv0 ~ 10-2 m/s are located. A seismic survey methodology sensitive to crustal flow v = φv0 at ℓ ~25m resolution has evolved from multi-channel seismic reflection technology applied to the production of shale hydrocarbons. The field-proven seismic flow-imaging methodology can be adapted from sedimentary terrains to volcanic terrains through appropriate seismic refraction means for generating effective seismic velocity models for convective geothermal flow volumes. Numerical simulation for characteristic ambient crustal heterogeneous flow distributions v = φv0 at ℓ ~50m resolution shows that travel-time data for seismic source energy refracted from deep geothermal wellbores to surface seismic sensor arrays can replicate the multi-channel seismic flow-imaging capability demonstrated for shale formations. Multi-channel seismic reservoir flow monitor detection and mapping of flow-induced seismic emissions in shale formations can be adapted to achieve similar mapping of convective geothermal flow system structures with v = φv0 ~ 10-2m/s at nominal ℓ ~ 50m resolution. Such seismic emission flow structure maps can greatly reduce the uncertainty and hence the cost of drilling effective production wells at brownfield sites and assessment/development wells at greenfield sites

On the seismic emission in sunspots associated with Lorentz force changes accompanying major solar flares

ABSTRACT Solar flares are known to generate seismic waves in the Sun. We present a detailed analysis of seismic emission in sunspots accompanying M- and X-class solar flares. For this purpose, we have used high-resolution Dopplergrams and line-of-sight magnetograms at a cadence of 45 s, along with vector magnetograms at a cadence of 135 s obtained from Helioseismic and Magnetic Imager instrument aboard the Solar Dynamics Observatory space mission. In order to identify the location of flare ribbons and hard X-ray footpoints, we have also used Hα chromospheric intensity observations obtained from Global Oscillation Network Group instruments and hard X-ray images in 12–25 keV band from the Reuvan Ramaty High Energy Solar Spectroscopic Imager spacecraft. The fast Fourier transform technique is applied to construct the acoustic velocity power map in 2.5–4 mHz band for pre-flare, spanning flare, and post-flare epochs for the identification of seismic emission locations in the sunspots. In the power maps, we have selected only those locations which are away from the flare ribbons and hard X-ray footpoints. These regions are believed to be free from any flare related artefacts in the observational data. We have identified concentrated locations of acoustic power enhancements in sunspots accompanying major flares. Our investigation provides evidence that abrupt changes in the magnetic fields and associated impulsive changes in the Lorentz force could be the driving source for these seismic emissions in the sunspots during solar flares.

ПРИМЕНЕНИЕ ТЕХНОЛОГИИ SANMCS ДЛЯ ОБРАБОТКИ ДАННЫХ МОРСКОЙ СЕЙСМИКИ

The article presents the results of applying the technology of spectral analysis of microseisms to marine seismic data. The fundamental differences between the software-algorithmic and methodological aspects of the processing of marine and land seismic data are described. Correlation of microseismic spectrum anomalies in the range of 4–8 and 10–15 Hz with a known oil accumulation is shown; the correspondence of another 10–15 Hz spectrum anomaly with gas condensate accumulation was also found. The conclusion about the seismic emission nature of microseism anomalies has been substantiated. The development process of seismic emission in time is considered. It was found that for each local emission zone, the beginning of the process development may have its own time. The duration of the maximum emission level phase is from 0.5 to 0.75 s. The stability of processing results is shown; local anomalies of the microseismic spectrum are traced on several parallel receivers lines that are 100 m apart from each other.

Earth’s gravity ― the reason of earthquakes

In the paper, an attempt has been made to describe seismic processes by means of classical mechanics. Dynamic parameters such as energy, impulse, and forces that determine the movement of masses are estimated. An earthquake model is regarded with consideration of the Earth gravity field influence on distribution of masses composing the Earth crust. The Earth crust is considered as a complex of geological bodies which is ordered by the planets gravity field. Due to isostasy the difference in density of the equal matter volumes leads to formation of mountain structures specific for the surface. When a base of such structures collapses a rock block shifts down and acquires mechanical impulse. Authors assume that this acquired mechanical impulse determines the earthquake’s magnitude. Impulse propagates in medium as a seismic wave. Front of the wave generates pressure effected on an environment that is not active yet. It determines macro-processes of the earthquake measured as earthquake intensity. Authors consider mass (weight) of a rocks block, magnitude (mechanical impulse acquired during an impact), seismic emission, which is a distribution of a momentum and a pressure of wave front (product of impulse by time), as parameters of a seismic process. To estimate dynamic parameters of earthquake processes, such as shifted mass, mechanical impulse, pressure of wave front, a nomogram is presented. Magnitude of a seismic event has dimension of a mechanical impulse, seismic intensity (earthquake intensity) has a dimension of pressure. Nomogram consists of several parts. The first one, allows analyzing the source of the emission. It shows the relation between emitted momentum, mass of a shifted body and energy. The next part of the nomogram represents momentum density per unit of area of the wavefront, which decreases in proportion to the square of a distance from the source. It characterizes the spherical propagation of seismic radiation in an isotropic medium. The third part of the nomogram helps to estimate the value of an average seismic pressure of the wavefront. The last part of the nomogram allows rating the empirical characteristics of a seismic event. A relation between a scale of seismic pressure and standardized scale of seismic intensity MSK-64 is established. As an example a Spitaka earthquake, December 7 th , 1988, was analyzed.

BARENTS-EURO/ARCTIC

Continuous seismic monitoring of the Kola Peninsula and the Spitsbergen archipelago with adjacent water areas was carried out. Seismic events were recorded using digital equipment. Operational catalogs of earth-quakes were compiled. Great attention is paid to the improvement of systems for seismic and infrasonic monitoring. Seventeen seismic events with magnitudes from 0.8 to 2.8 which can be interpreted as tectonic earthquakes were recorded in the Baltic Shield area. The strongest earthquakes were recorded in the Arkhangelsk region (28.03.2013, M=2.9), in northern Norway (09.02.2013, MLрег=2.8), and in northern Finland (21.11.2013, MLрег=2.7). The maximum magnitude of the event in the Murmansk region was 2.3. The seismic activity in 2013 was the lowest over the last five-year period (from 2009 to 2013). The Spitsbergen archipelago was characterized by the smallest number of earthquakes in all ranges of magnitudes and by the smallest amount of released seismic energy for the five-year period from 2009 to 2013. The experimental research to monitor seismic and infrasonic emissions generated by glaciers was carried out using a seismic and infrasonic system installed before in the Spitsbergen archipelago. In particular, the seismic emission generated by the Isfjord glaciers has a strong seasonality. Activation is observed in the second half of summer and continues until the 20th of September. As a result of the studies, the possibility of remote monitoring of the destruction of glaciers by the seismic and infrasonic method was convincingly demonstrated

Research Note: Frequency domain orthogonal projection filtration of surface microseismic monitoring data

ABSTRACTWe address the problem of increasing the signal‐to‐noise ratio during surface microseismic monitoring data processing. Interference from different seismic waves causes misleading results of microseismic event locations. Ground‐roll suppression is particularly necessary. The standard noise suppression techniques assume regular and dense acquisition geometries. Many pre‐processing noise suppression algorithms are designed for special types of noise or interference. To overcome these problems, we propose a novel general‐purpose filtration method. The goal of this method is to amplify only the seismic waves that are excited in the selected target area and suppress all other signals. We construct a linear projector onto a frequency domain data subspace, which corresponds to the seismic emission of the target area. The novel filtration method can be considered an extension of the standard frequency–wavenumber flat wave filtration method for non‐flat waves and arbitrary irregular receiver‐position geometries. To reduce the effect of the uncertainty of the velocity model, we suggest using additional active shot data (typically the perforation shots), which provide static travel time corrections for the target area. The promising prospects of the proposed method are confirmed by synthetic and semi‐synthetic data processing.

Application of Robust Phase Algorithms for Seismic Emission Detection in the Area of Blasting Operations in Mines

In this paper, we developed algorithms for multichannel processing of seismic array records that allow detecting signals of weak seismic events observed against the background of natural seismic noise. The algorithm for detecting signals of weak seismic events is based on the coherence assessment of longitudinal waves (P-waves) recorded by a small aperture array. The advantage of this algorithm over the known single-channel short/long term averaging (STA/LTA) detector is the ability to detect time intervals of P-waves at a signal-to-noise ratio (SNR) less than unity. Based on the time intervals of the array records with the registered coherence measure values that ​​exceed a certain threshold, the apparent slowness vector is estimated by using the phase bimforming algorithm that is robust to noise (Zhang et al., 2008; Kushnir and Varypaev, 2017). The developed algorithms of multichannel processing were tested using real seismic records of a small aperture array installed in the Kursk Magnetic Anomaly area near the mine workings for iron ore extraction. Signals of both strong (underground industrial explosions) and weak seismic events were detected for 20 h of seismic recording. In some cases, seismic events were shown to have a complex source mechanism. Using the Capon filter (Capon, 1969), for weak seismic events, P-waves with a duration not exceeding 0.2 s and a temporal shape similar to the known function of a Ricker pulse (Bording, 1996) are found to have resemblance.