Monitoring Of Seismic Activity Research Articles

Feasibility of targeted active seismic monitoring of geological carbon storage using refracted waves

Active seismic monitoring is a powerful technique that can be employed for conformance and assurance monitoring in geological carbon storage (GCS). This technology was successfully deployed in small-scale research studies and large-scale commercial projects. Usually, in land time-lapse surveys, to ensure time-lapse data quality, the seismic survey is designed to have a very high trace density. This increases the cost of the survey and usually results in high-quality data covering only a very limited area. While this is a good approach if the detailed plume image is required, massive uptake GCS would require the monitoring to be cost-effective. Therefore, it is important to explore the possibility of using a series of daisy-chained wells instrumented with distributed acoustic sensors and paired to permanent seismic sources as a basis for such a system.To this end, we propose using head waves instead of reflected waves in large-scale projects for conformance monitoring (and, maybe, large leakage detection). Using a cartoon model of CarbonNet Pelican site as a motivation, we perform a feasibility study through seismic modelling. We also simulate a similar monitoring approach for a forthcoming shallow fault injection at the CO2CRC's Otway site in the Australian State of Victoria. This experiment can be viewed as a scaled model for larger injections. Based on these modelling results, we provide a short overview of the further field experiments that can be used to validate the proposed approach.

The Effect of Earthquake Disaster Management Preparedness Knowledge and Training on Midwife Preparedness in Central Aceh Regency, Indonesia

The threat of an earthquake has received wide attention, because it is sudden, predictable, but difficult to determine when it will occur. Predictions are based on the monitoring of seismic activity, historical records and observations. Disasters always have an adverse impact, such as damage to physical facilities and infrastructure (residential housing, office buildings, schools, places of worship, roads, bridges and others). Midwives are health workers who generally work in Health Center or in the community/community closest to the impact of the disaster. The contribution of the midwife to disaster/emergency risk reduction or preparedness is very important. Meanwhile, midwives are often not included in the workforce for disaster preparedness at local, national and international levels. This study aimed to determine the effect of knowledge and training on earthquake disaster preparedness on the preparedness of midwives in Central Aceh Regency. This study uses a survey research design that is analytic in nature with an approach cross-sectional which is measured at the same time as the research takes place and tested through hypothesis testing. The sample is 208 samples. The sampling method in this study was carried out proportionally in proportion to the total population spread across 14 Districts in Central Aceh Regency. The results of the study show that there is an influence of knowledge variables (p = 0.018), and disaster training (p = 0.000). This shows that knowledge and training have a relationship and influence on earthquake disaster preparedness in Central Aceh Regency.

Monitoring of seismic activity in near-wall rock masses of open pits using seismic recorders in deep boreholes beyond the final pit boundary

Monitoring of seismic activity in near-wall rock masses of open pits using seismic recorders in deep boreholes beyond the final pit boundary

Distributed acoustic sensing time-lapse vertical seismic profiling during zipper-fracturing operations: Observations, modeling, and interpretation

Recent advances in distributed acoustic sensing (DAS) technology allow active seismic monitoring of stimulated rock volume (SRV) development. We showcase an interstage DAS vertical seismic profiling survey acquired during a zipper-fracturing stimulation. Incident P waves scattered by the SRV and converted to S waves are observed in the data. The signals are associated not only with hydraulic fracturing stages of the instrumented well but also with the fracturing of an adjacent well in the zipper group. A workflow is developed to monitor and characterize the SRV, fracture closure time, and interactions between zipper wells. The 3D full-wavefield modeling confirms the data interpretation and provides additional insight. As a result, we have been able to estimate SRV properties, including SRV height, width, and the fracture closure time for all wells within the zipper group. Moreover, for adjacent wells, the length and azimuth of SRV can be constrained. Our work provides critical information for optimizing hydraulic fracturing operations.

Preliminary assesment of ADIS16470AMLZ sensor for monitoring of seismic activity in mining area

Preliminary assesment of ADIS16470AMLZ sensor for monitoring of seismic activity in mining area

Organization of the stationary seismological observations point

The Institute of Geophysics of the NASU organizes and carries out continuous regional and local seismic observations on the territory of Ukraine. The article presents a universal modern model of seismic activity monitoring process, which is used in most international seismological agencies (USGS, EMSC, NEIC) and describes a typical stationary point of seismological observations of the National Seismological Network of the Institute of Geophysics of NAS of Ukraine. Seismological network of observations is a complex of systems consisting of stationary seismological points of registration of seismic waves, the distributed system of transfer and collecting of the seismological information, and also the center of operative processing of the data arriving from data registration points. The process of conducting regime seismological observations of local and remote seismic events on the territory of Ukraine and adjacent regions is described. Some important aspects of the need for comprehensive processing of registered events to identify local earthquakes and assess the current activity of tectonic structures in Ukraine are presented. The seismological network of the National Seismological Center of the Institute of Geophysics of the National Academy of Sciences of Ukraine is represented by a small number of stationary observation points: «Kiev-IRIS», «MI02-Poltava», «MI03-Skvyra», «MI04-Dnipro», «MI05-Stepanivka», «MI07-Mykolaiv», «ODS-Odesa», «MIU-Kryvyi Rih», and «MI06-Kremenchug». This number of seismological observation points does not actually provide seismic observation data to the central, eastern and southern parts of the territory of Ukraine and does not allow to reliably determine the level and quantitative characteristics of its seismic hazard. The seismic recorder Guralp CMG-40T manufactured by the British company GURALP SYSTEMS LIMITED is offered as optimal for the conditions and financial realities of Ukraine when organizing a stationary seismic observation point. It is proposed to use the seismological processing package SeisComP, which works on the SeedLink protocol, which is the basis of the data collection system by the Internet. This software product is the de facto world standard in the field of seismological data processing.

The capabilities of analyzing the seismo-electromagnetic satellite CSES-01 data for monitoring of seismic activity of the Northern Tien Shan

The relationship between space weather and earthquakes occurring in seismically active areas with the seismo-electromagnetic satellite CSES-01 data are observed. The study assumes the presence of possible ionospheric precursors of strong earthquakes. The sets of measuring instruments of the satellite and data are considered. Subsequently, to prove the non-random nature of the space weather effects, the results of ground-based geomagnetic or electromagnetic observations should be used, for example, magnetotelluric soundings (MTS). Stationary and regime points of the MTS network of the Research Station RAS in Bishkek (RS RAS) are suitable for these purposes in the Northern Tien Shan. The MTS data are presented in the form of hourly frequency-time series with system rotation from 0° to 180°. To obtain information on earthquakes, it is proposed to use data from the NEIC or ISC seismic catalog, since they aggregate data from regional catalogs, including the KNET seismological network maintained by the RS RAS. It is concluded that it is necessary to select the CSES-01 trajectories and times of flight over the territory of Kyrgyzstan and download the electric field detector (EFD) data. The results of comparing satellite and ground-based observations can be used in future technologies for short-term earthquake prediction.

Distributed acoustic sensing/surface orbital vibrator: Rotary seismic sources with fiber-optic sensing facilitates autonomous permanent reservoir monitoring

With new developments of fiber-optic sensing and rotary sources, continuous active seismic monitoring for onshore applications has now the opportunity to be fully realized and applied to enhance subsurface resource extraction and use. To date, conventional seismic monitoring deployments have primarily consisted of receiver arrays, either fixed or not, with periodic data acquisition campaigns using temporarily deployed sources, resulting in time-lapse data with poor temporal resolution. Only a few niche efforts have demonstrated continuous acquisition using fixed source-receiver networks. We have evaluated the initial results of a network of fixed rotary seismic sources, referred to as surface orbital vibrators (SOVs), coupled with a permanent distributed acoustic sensing (DAS) network at the CO2CRC Otway Field Site. Although rotary seismic sources are not new, our development of the SOV focused on simplifying the cost and complexity of the source hardware while delivering broad frequency spectrum of the source signal. The upgraded hardware is aligned with a robust methodology for autonomous operation and data processing. At the Otway Site, we deployed SOVs at nine locations, monitoring seismic response in seven DAS instrumented wells. Baseline operation of the DAS/SOV sensor array and source system demonstrates its capability with near offsets attaining a signal-to-noise ratio approaching 100 dB with a normalized root mean square of 10%. Furthermore, analyses of traveltime repeatability indicate that the DAS/SOV system can deliver time resolution of ±500 μs.

Seismic activity of hard coal longwall mining in protective shaft pillar near closed room and pillar panel

Monitoring of seismic activity during mining in the Upper Silesian Coal Basin is a part of rockburst prevention system. System is composed from two parts - seismological (SL) and seismoacoustic (SA) monitoring. Evaluation of data from both systems allows describing stress deformation process during mining and evaluation of rockburst mitigation techniques effectiveness. Described longwall was mining in a protective pillar after two trial room and pillar (R&P) testing panels were completed.Evaluation of seismic activity was carried out by special software tool which allows simulating daily advance of mining and registered seismic activity. Different mining stages were identified for evaluation of seismic activity (e.g. weekly and daily summary graph of seismic activity, Benioff graph, event rate graph, energy vs time graph etc.). Evaluation of seismic activity provides many interesting results, mainly in the area of longwall panel termination when one pillar of the R&P trial was impacted by the longwall. This work presents seismic activity analysis, detailed site conditions and implemented active rockburst measures and its effectiveness. Analysis of seismic activity allows to formulate conclusions for longwall mining operations and evaluation of seismic activity in unfavourable geomechanical conditions within the area of protective shaft pillar border.

Machine Learning Predicts the Timing and Shear Stress Evolution of Lab Earthquakes Using Active Seismic Monitoring of Fault Zone Processes.

Machine learning (ML) techniques have become increasingly important in seismology and earthquake science. Lab‐based studies have used acoustic emission data to predict time‐to‐failure and stress state, and in a few cases, the same approach has been used for field data. However, the underlying physical mechanisms that allow lab earthquake prediction and seismic forecasting remain poorly resolved. Here, we address this knowledge gap by coupling active‐source seismic data, which probe asperity‐scale processes, with ML methods. We show that elastic waves passing through the lab fault zone contain information that can predict the full spectrum of labquakes from slow slip instabilities to highly aperiodic events. The ML methods utilize systematic changes in P‐wave amplitude and velocity to accurately predict the timing and shear stress during labquakes. The ML predictions improve in accuracy closer to fault failure, demonstrating that the predictive power of the ultrasonic signals improves as the fault approaches failure. Our results demonstrate that the relationship between the ultrasonic parameters and fault slip rate, and in turn, the systematically evolving real area of contact and asperity stiffness allow the gradient boosting algorithm to “learn” about the state of the fault and its proximity to failure. Broadly, our results demonstrate the utility of physics‐informed ML in forecasting the imminence of fault slip at the laboratory scale, which may have important implications for earthquake mechanics in nature.

Noise classification for the unified earthquake catalog using ensemble learning: the enhanced image of seismic activity along the Japan Trench by the S-net seafloor network

Homogeneous and accurate hypocenter distribution along the Japan Trench is important to better understand the process of plate subduction and the occurrence mode of large earthquakes. The seafloor seismic network (S-net) deployed recently along the Japan Trench has revealed new seismic activity including shallow slow earthquakes. However, conventional microseismic observations, such as those reported in the Japan Meteorological Agency (JMA) unified earthquake catalog, have been limited to land-based stations. Thus, steady seismic activity occurring at the shallow plate boundary, which is far from land is not always recorded. In the present study, we construct an automatic earthquake catalog using the nationwide observation network, including S-net. Because false detections caused by noise account for about 5% of automatically determined hypocenters, we attempted to reduce false detections using ensemble learning methods such as random forest and AdaBoost. First, we created a training dataset of earthquakes and noise by visual inspection based on the data recorded in the automatically determined catalog over a 2-month period, and we trained the dataset using the hypocenter and phase data as input. As a result of the training, AdaBoost was able to reduce the noise to about one-fifth of the total false detections, which is equivalent to 1%, while keeping the number of hypocenters above 99%. This method will contribute to significantly improving the efficiency of seismic activity monitoring and cataloging. In addition, the automatic denoised catalog data revealed that from January to August 2020, the completeness magnitude was M 1.6 along the Japan Trench. These microearthquakes were concentrated at depths of 20–50 km around the upper surface of the subducting Pacific Plate and are complementary to the slow earthquakes occurring at 10–20-km depths. Exceptionally, microearthquakes were observed off Iwate and Ibaraki prefectures, which correspond in location to areas of clustered foreshock activity. This spatial heterogeneity in microseismic activity is similar to the spatial complementary between the coseismic slip and afterslip of the 2011 Tohoku earthquake, which may be related to differences in interplate frictional properties and stress changes in the surrounding crust.

Basic principles for building seismic monitoring systems in rockburst-hazardous coal seam mining

The main directions of development of seismic monitoring systems in underground mineral mining are analyzed. The expediency of passive registration of natural seismic activity is proved, which provides prediction of geodynamic phenomena by locating the centers of seismic events and determining their energy level. The methods of active seismic monitoring (seismic tomography, cross-borehole survey, recording of seismic signal from a rock-breaking tool) are technically more difficult to implement. The promising methods for processing seismic information are geolocation, neural network technology, cluster analysis, and integration with numerical stress–strain analysis of and changes in acoustic properties of rock mass. The configuration of the platform developed at VNIMI and the GITS seismic monitoring system, which includes from 6 to 12 three-component seismic sensors installed permanently in wells or on pedestals, is described. The detailed layouts of seismic sensors at recording points and in gateways in extraction panels are presented. The main technical characteristics of GITS are given: the signal frequency range is 0.1–1000 Hz, the minimum recorded signal level is 0.01 mV. The main test data of GITS in Komsomolskaya mine of Vorkutaugol are described: the average annual levels of seismic activity and energy of seismic events are found to be relatively stable; the relationship between seismic event with the maximum total energy and the alternating increment in the relative criterion is defined, and the local increase in the average energy of a single event in time from the moment the main roof caving is identified. Aimed to substantiate the regional and local prediction criteria of probability of geodynamic events caused by confining pressure, VNIMI implements integrated research in mines in different regions.

LORS2 Software Package for Monitoring the Seismicity of the Khibiny Massif: Construction Principles and Basic Algorithms

The paper describes a software package developed for automated monitoring of seismic activity of the Khibiny mountain massif. The general structure of the software package is described, and the applied methods and algorithms are considered in detail. In particular, the algorithm for locating the source of a seismic event via grid searches, which are specified as sets of circles and are categorized during execution of the algorithm, is described in detail. The proposed location methods are combined into several packages—scenarios to optimize the time spent by a geophysicist in routine interactive processing of a large dataset. Because the described software package was created to process data from seismic networks located directly in the mining area, much attention is paid to increasing the reliability of detecting target signals in a high-noise environment and the accuracy in determining the arrival times of body waves. To solve these problems, the system implements a new approach to locating close events, based on the idea of a holistic perception of a signal record, which is very close to the concept of human perception of objects. The algorithms and methods for detecting and locating seismic event generation sites implemented in the software package can significantly increase the reliability of the solutions obtained and increase the accuracy and efficiency of the final interactive processing of seismic signal records.

Distributed acoustic sensing for seismic activity monitoring

Continuous, real-time monitoring of surface seismic activity around the globe is of great interest for acquiring new insight into global tomography analyses and for recognition of seismic patterns leading to potentially hazardous situations. The already-existing telecommunication fiber optic network arises as an ideal solution for this application, owing to its ubiquity and the capacity of optical fibers to perform distributed, highly sensitive monitoring of vibrations at relatively low cost (ultra-high density of point sensors available with minimal deployment of new equipment). This perspective article discusses early approaches on the application of fiber-optic distributed acoustic sensors (DASs) for seismic activity monitoring. The benefits and potential impact of DAS technology in these kinds of applications are here illustrated with new experimental results on teleseism monitoring based on a specific approach: the so-called chirped-pulse DAS. This technology offers promising prospects for the field of seismic tomography due to its appealing properties in terms of simplicity, consistent sensitivity across sensing channels, and robustness. Furthermore, we also report on several signal processing techniques readily applicable to chirped-pulse DAS recordings for extracting relevant seismic information from ambient acoustic noise. The outcome presented here may serve as a foundation for a novel conception for ubiquitous seismic monitoring with minimal investment.

On the Variability of Pressure Propagation During Hydraulic Stimulation Based on Seismic Velocity Observations

AbstractPermeability enhancement of a reservoir through hydraulic stimulation is ever so often accompanied by potentially hazardous induced seismicity. Monitoring of in situ pressure propagation remains an important step in understanding the underlying seismo‐hydromechanical processes during hydraulic stimulation and mitigating hazardous induced seismicity. In an effort to monitor pressure propagation remotely, active seismic monitoring was performed during decameter‐scale hydraulic stimulation experiments at the Grimsel Test Site in Switzerland. Using cross‐correlation schemes, subtle traveltime variations that correlate well with the high‐pressure fluid injections during hydraulic stimulation become apparent. The 4‐D seismic tomograms obtained through time‐lapse differential traveltime inversion reveal transient changes in the seismic velocity within the stimulated volume that depend on the effective stress. In‐depth comparison of the seismic velocity variations and measured pressure data indicates that the seismic velocity variations can be used as a proxy for pressure propagation within an equilibrated system. Observations show that traveltime tomography is insensitive to isolated, high‐pressure variations such as a breakthrough within the fracture network. Joint interpretation of the 4‐D seismic tomograms with geological and hydromechanical data reveals fundamental differences between the different experiments due to a large variability in the rock mass response to the hydraulic stimulation. Using the observed velocity variations as a proxy for pressure propagation, we can infer characteristics of the shear zones and the rock volume at the Grimsel Test Site. The observed velocity variations provide not only information on the characteristics of the reservoir itself but also its response to different stimulation techniques.

Tectonic Controls on Near-Surface Variations in CH4 and CO2 Concentrations along the Northwestern Margin of the Ordos Block, China

Tectonic controls on near-surface CH4 and CO2 concentrations were investigated by measuring CH4 and CO2 concentrations at the surface and a height of 1.5 m, in the different tectonic units that comprise the northwestern margin of Ordos Block, China, which has a complex tectonic structure and a history of strong earthquakes. CH4 and CO2 concentrations varied from 1905 to 2472 ppb and 397.5 to 458.5 ppm, respectively. Surface CH4 and CO2 concentrations were generally higher than those measured at 1.5 m, but showed similar trends, indicating that the measured CH4 and CO2 predominantly originated from underground gases. The CH4 and CO2 concentrations increased with an increasing strike-slip rate across the faults, and concentrations in the blocks with high internal deformation were much higher than those measured in the stable blocks. Regions of extensional deformation had higher gas concentrations than regions that had experienced compressional deformation. The spatial distribution of CH4 and CO2 at the study site had similar trends to faults associated with the Yinchuan Graben. The results of this study indicated that gas source, gas migration pathway, and tectonic stress were the main factors that influenced gas emission. The key factor is tectonic stress, which controlled the formation of tectonic structures, changed the pathway of degassing, and acted as the driving force for gas migration. The results of this study clarify the mechanism of CH4 and CO2 degassing in faulted regions and suggest that CH4 and CO2 concentrations may be useful precursors in the monitoring of seismic activity. The results may also help inform future assessments of the contribution of geological sources to greenhouse gas emissions.

Equipment and method for remote monitoring of seismic activity by VLF electromagnetic signals

A one-point system equipment and a method used for remote monitoring of seismic activity in the lower ionosphere by electromagnetic signals of lightning discharges with observations in Northern Asia are described. Experimental results of detecting of ionospheric effects of strong earthquakes are considered. The effects of shallow-focus earthquakes with magnitudes larger than 5.0 and their precursors manifest themselves in the amplitude characteristics of atmospherics. It is assumed that the variations in the signal characteristics are related to disturbances in the lower ionosphere. Statistical studies of the detection of ionospheric effects during strong earthquakes are carried out. To increase the accuracy and statistical significance of the results, it is proposed to use a multi-point system. A new software-hardware complex called «Sensor signal analysis network» (SSAN), whose endpoints are located in the territory of Northern Asia for synchronous recording of VLF/LF electromagnetic signals of lightning discharges and VLF-transmitters, is planned to be used to study lithospheric-ionospheric disturbances in the main zones of seismic activity.

On the monitoring of seismic activity using the algorithms of discrete mathematical analysis

On the monitoring of seismic activity using the algorithms of discrete mathematical analysis

On monitoring of seismic activity

The article offers a new wireless system, which allows monitoring the seismic activity effectively due to the ease of deployment, use, reliability of work; it also allows dividing modules and information processing system; it ensures the independence of each module and information processing system from each other and eliminates the cost of wired connections. Using the wireless connection and the key connected to the pulse receiver provides access to the modules in a random order. The article provides the description of the operating principle of a wireless system that is territorially distributed. The structural diagrams of the sensor node, the base station, the structural electrical circuit of the sensing element of the node and the frequency generators of the radio transmitting devices of the base station, as well as the sensor node are shown, calculation of the sensory element of the sensor node is given. Using the microprocessor as a control unit allows you to improve accuracy and speed. It is noted that it is possible to increase the coverage area of the system by installing additional base stations, as well as the use of a mixed topology that includes links with the star topology and cellular network.

Low enthalpy Na-chloride waters from the Lunigiana and Garfagnana grabens, Northern Apennines, Italy: Tracing fluid connections and basement interactions via chemical and isotopic compositions

The Na-Cl waters from NW Tuscany (central Italy) record similar water isotopic and major chemical compositions, which demonstrate their meteoric origin and interactions with Upper Triassic evaporites and the metamorphic units of the Paleozoic basement. Slight differences are found in the deep temperature-pressure conditions of the Lunigiana graben (39–42°C/143–145bar) and the Garfagnana graben (73–78°C/250–256bar). In particular, the thermal fluids outpouring from Garfagnana are probably related to a common deep reservoir or interconnected fluids. Their differences are mainly evidenced by strontium isotopic ratio data (87Sr/86Sr), which combined with previously published sulfur isotope ratios (34S/32S) demonstrate the involvement of vein barites in water-rock interactions. Most likely, these minerals formed during Upper Oligocene-Miocene tectogenesis due to the mixing of fluids from the Verrucano Group and Upper Triassic units. The results of this hydrogeochemical study of the deep Na-Cl fluids could better clarify the distribution of the Verrucano Group within this area and the related discrepancies in the stratigraphic interpretations of the Palaeozoic-Mesozoic transition. Furthermore, the possible presence of an interconnected reservoir could be used to help interpret data produced by the local geochemical monitoring of seismic activity.