Microseismic Method Research Articles

Subsurface Sediment Layer Analysis at the Dendam Tak Sudah Lake Flyover Construction Site in Bengkulu City Using the HV-Inv Method

Bengkulu City is situated within a subduction zone where the Indo-Australian and Eurasian tectonic plates converge, rendering the area highly susceptible to seismic activity. This study employs the microseismic method to assess seismic vulnerability and the subsurface rock structure at the Dendam Tak Sudah Lake Flyover Construction Site in Bengkulu City, which encompasses a swampy region. The microseismic method used was an inversion of the horizontal to vertical (H/V) spectral ratio (HV-Inv) for determining the dominant frequency (f0), amplification factor (A0), seismic sensitivity index (Kg), and shear wave velocity (Vs). The findings reveal that f0 in the study area range from 2.16 to 7.53 Hz, A0 vary from 0.40 to 3.79, and Kg values span from 0.03 to 6.04. The sedimentary layers exhibit an average thickness of 5-10 meters, with some locations showing significantly thicker sedimentary deposits. Notably, the highest seismic susceptibility is recorded at point T8. The Vs values range from 185.19 to 539.49 m/s, which are inversely proportional to the Kg values and indicate soil classifications varying from soft to medium. The overall seismic risk in the study area is moderate. These results offer key insights into geophysical and geological conditions in Bengkulu City, crucial for earthquake mitigation.

Integration of deep-learning fault segmentation, horizontal transverse isotropy analysis, and ambient microseismic methods to enhance fracture prediction in the Crisol Anticline, Colombia

The analysis of fault and fracture systems in the subsurface is crucial for identifying potential reservoirs and optimizing production. However, conventional fault interpretation methods have limitations due to the complexity and amount of data involved. In this study, a multimethod approach was used to analyze fault and fracture systems in the Crisol area of the Valley Middle Magdalena basin. We used deep-learning fault segmentation, horizontal transverse isotropy (HTI), and ambient microseismic methods to identify and characterize fault and fracture systems in the study area. The deep-learning fault segmentation method helped to identify complex fault systems, whereas the HTI method identified areas and orientations of intense fracturing that occurred at any prior period of stress in geologic time. Meanwhile, the ambient microseismic method measured active rock movements and fracturing in the subsurface that occurred during the microseismic trace recording. The application of multiple methods for analyzing fault and fracture systems in the subsurface is demonstrated to offer a more comprehensive understanding of the geology and enhance the accuracy of well placement and production forecasts.

MICROZONING OF HAZARD VULNERABLE USING MICROSEISMIC METHOD WITH HVSR (HORIZONTAL TO VERTICAL SPECTRAL RATIO) ANALYSIS IN BAYAT DISTRICT, KLATEN, INDONESIA

The Yogyakarta earthquake in 2006 caused damage in several areas, especially in the area of Klaten Regency. As a result, many infrastructures, houses, health facilities and casualties have been damaged. The research was conducted with the target of knowing the level of earth's hazard by microzoning soil vulnerability areas in the Bayat District, Klaten, Central Java. This study used the microseismic method with the HVSR (Horizontal to Vertical Spectral Ratio) analysis method. Where are the natural/dominant frequency parameters, natural amplification, and earthquake vulnerability index as measured parameters? This study aims to carry out microzonation of disaster vulnerability risks which are interpreted from the results obtained, namely amplification maps (A0), dominant frequency (f0), earthquake vulnerability (Kg), and shear wave velocity maps at a depth of 30 meters (Vs30). Data acquisition was carried out at 19 measurement points with a spacing between points having a distance of 1-2 km using a portable TDS seismograph. The acquisition results obtained varied values with A0 values 0.9 – 8.8, f0 values 1.0 – 13.8 Hz, Kg values 0.4 – 38.5, and Vs30 values 228.1 – 1635.4 m/s. From these results it can be categorized as zoning regarding the value of the level of disaster vulnerability based on the value of earthquake vulnerability (Kg) obtained to minimize damage and casualties

Identification of Seismic Response to Aquifer System with A Synthetic Modelling Approach

The microseismic method is relatively new in groundwater exploration, especially in Indonesia. This study will examine the response of microseismic to groundwater aquifer systems. This study aims to analyze the response of seismic waves and to interpret the seismic wave response characteristics to the aquifer system model. The modeling of the aquifer system was carried out using seismic stratigraphy data. This data was used as input data to model the exposed HVSR curve using the Microtrem program in MATLAB. The study of physical parameters and supporting parameters of the aquifer layer and the air contained in it was carried out to support this modeling. The aquifer system modeling was carried out with various parameters, including saturation, porosity, and thickness of the aquifer layer. Furthermore, an analysis of the model is carried out to determine the response characteristics of the aquifer system to microseismic waves. The results show that the frequency range as a marker of the presence of the aquifer ranges from 2-4 Hz, which is determined by parameters within a specific value.

Effects of bedding planes on progressive failure of shales under uniaxial compression: Insights from acoustic emission characteristics

It is believed that the bedding plane is one of controlling factors in progressive failure of shales and its characterization is of great significance in the gas shale engineering. However, it is often difficult to directly capture and visualize the progressive failure process of shales in practice. Although the microseismic method is feasible and economical to overcome this problem, to date, the effect of bedding plane on progressive failure of shales is still not fully clarified by this method. Here, we use the bonded-particle model (BPM) embedded with moment tensor algorithm to explore the progressive failure process and acoustic emission (AE) characteristics of shales under uniaxial compression. The macro mechanical behaviors such as stress-strain response and failure modes of shales were well reproduced by BPM. Meanwhile, AE characteristics were systematically monitored and analyzed during the progressive failure process. Then, the failure type dependent on layer orientation was determined by the moment tensor decomposition. And bedding-orientation-controlled crack stress thresholds as well as the degree of progressive failure could be captured by the AE cumulative number and hits. It was found that b-value in post-peak stage was susceptive to layer orientation and could be used as the indicator of the fracture complexity. Also, proportion of shear AE sources have a good consistence with fracture complexity, which suggests that shear failures favor the complex fracture formation. Our study provided a new insight into effects of bedding planes on progressive failure of shales from the viewpoint of AE characteristics.

Application of a Microseismic Method of Rock Burst Risk Assessment under Blasting Mining in Ashele Copper Mine

Rock burst is a violent release of energy stored in the rock mass, which has been the focus of metal mine engineers. It gradually becomes a serious threat to both the mine’s workers and equipment. Rock burst risk assessment is a key issue in the prevention of rock burst. Based on the microseismic method for rock burst risk assessment that is used in tunnels, this paper presents a method of rock burst risk assessment for metal mines combining a simplified probability function and principal component analysis (PCA). Specifically, the size and details of key monitoring area and risk assessment units are determined according to the distribution of the fracture and driving stress during deep mining process. Based on the correlation analysis, six microseismic parameters are selected to be used for rock burst risk assessment. Simple linear functions are temporarily used to construct probability functions of each parameter before enough rock burst cases are collected. The method has been successfully used in the deep mining section of the Ashele Copper Mine (approximately 1000 m deep). Additionally, among various microseismic indicators, the energy release rate and cumulative energy are the greatest contributors to rock burst of different intensities. Therefore, the proposed method in this paper provides an important reference for the prevention and control of rock burst in metal mines.

Analysis of Seismic Hazards and Vulnerability throughout Indonesia Based on 1999-2003 Earthquake Data Using the Microseismic Method

Indonesia is an archipelagic country that has a complex geological structure. Its location at the confluence of three plates, namely the Eurasian plate, the Indo-Australian plate, and the Pacific plate causes high tectonic activity. This seismic activity causes high seismicity levels, especially along the subduction zone. An earthquake with a large magnitude can occur and cause a high level of damage, so it is necessary to know about the language of earthquake resistance. Earthquake vulnerability is useful for mitigating earthquakes that will occur so that people are more alert to earthquake disasters that can occur anytime and anywhere. This research is a descriptive type of research, namely by collecting data on the JINSET (Japan Indonesian Seismic Network) earthquake catalog in 1999-2003 with M greater than 5 S.R. Earthquake hazard data processing using geopsy software for HVSR analysis. The horizontal component data is divided by the vertical component in the frequency domain so that the H/V value is obtained.

Analysis on Rock Burst Risks and Prevention of a 54 m-Wide Coal Pillar for Roadway Protection in a Fully Mechanized Top-Coal Caving Face

A case study based on the 401103 fully mechanized caving face in the Hujiahe Coal Mine was carried out in this research to analyze the rock burst risks in a 54 m-wide coal pillar for roadway protection. Influencing factors of rock burst risks on the working face were analyzed. Stress distribution characteristics on the working face of the wide coal pillar for roadway protection were discussed using FLAC3D numerical simulation software. Spatial distribution characteristics of historical impact events on the working face were also investigated using the microseismic monitoring method. Results show that mining depth, geological structure, outburst proneness of coal strata, roof strata structure, adjacent mining area, and mining influence of the current working face are the main influencing factors of rock burst on the working face. Owing to the collaborative effects of front abutment pressure of the working face and lateral abutment pressure in the goaf, the coal pillar is in the ultimate equilibrium state and microseismic events mainly concentrate in places surrounding the coal pillars. Hence, wide coal pillars become the regions with rock burst risks on the working face. The working face adopts some local prevention technologies, such as pressure relief through presplitting blasting in roof, pressure relief through large-diameter pores in coal seam, coal seam water injection, pressure relief through large-diameter pores at bottom corners, and pressure relief through blasting at bottom corners. Moreover, some regional prevention technologies were proposed for narrow coal pillar for roadway protection, including gob-side entry, layer mining, and fully mechanized top-coal caving face with premining top layer.

Multi-sensing investigation of crack problems for concrete dams based on detection and monitoring data: A case study

Cracks, a major issue in concrete structures, will reduce structural integrity, stability and impermeability. In this paper, a comprehensive site crack status monitoring system was constructed in a roller compacted concrete (RCC) gravity dam during the construction period, by combining acoustic emission (AE), micro-seismic (MS), cross-hole acoustic wave detection (CAWD), crack gauge and strain gauge techniques; this system was used to investigate crack development problems that may occur under varying construction conditions. Through knocking location tests, the acoustic wave transmission rate of RCC was determined by the AE and MS system, to monitor the real-time status of micro-cracks. Moreover, the crack tip displacement, adjacent concrete strain and concrete ultrasonic velocity were captured, to monitor the propagation of macroscopic cracks. By combining the information obtained at both the micro- and macro- levels, the development trend of a crack was analyzed. Results show that micro-crack signals were captured, but the sensitivity of the AE approach was relatively smaller than that of MS method, and the crack status was in the structural internal stress adjustment stage. On the macro-level, the macroscopic expansion phenomenon of the original crack was not captured by the crack gauge, strain gauge and acoustic penetration. Based on the size, the concentration of micro-cracks and the development trend of the macro-cracks monitored by the multi-sensing system, the crack behavior can be evaluated in huge concrete infrastructures.

The Use of Intelligent Sensing Algorithm for Internet of Things and Hash Spatial Information Location Technology

This exploration is aimed at quickly obtaining the spatial position information of microseismic focal points and increasing the accuracy of microseismic rapid positioning, to take timely corresponding measures. A microseismic focal point location system completely different from the traditional microseismic location method is proposed. The search engine technology is introduced into the system, which can locate the microseismic focal point quickly and accurately. First, the propagation characteristics of microseismic signals in coal and rock layers are analyzed, and the focal position information is obtained. However, the collected microseismic signal of the coal mine contains noise, so it is denoised at first. Then, a waveform database is established for the denoised waveform data and focal point position. The structure and mathematical model of the location‐sensitive hash (LSH) based on P stable distribution are introduced and improved, and the optimized algorithm multiprobe LSH is obtained. The microseismic location model is established according to the characteristics of microseismic data. The values of three parameters, hash table number, hash function family dimension, and interval size, are determined. The experimental data of the parameters of the search engine algorithm are analyzed. The results show that when the number of hash tables is 6, the dimension k of the hash function family is 14, and the interval size W is 8000, the retrieval time reaches a relatively small value, the recall rate reaches a large value, and the proportion of retrieved candidates is large; the parameters of the search engine algorithm of the measured coal mine microseismic data are analyzed. It is obtained that when the number of hash tables is 4, the dimension k of the hash function family is 6, and the interval size W is 500, the retrieval time reaches a relatively small value, the recall rate obtains a large value, and the proportion of retrieved candidates is large. The contents studied are of great significance to the evaluation of destructive mine earthquakes and impact risk.

Identification of Subsurface Lithology in Sendang Mulyo, Purwoharjo Village, Samigaluh Subdistrict, Kulon Progo Regency

Research aimed to determining the lithological conditions subsurface of landslide areas in Sendang Mulyo, Purwoharjo Village, Samigaluh Subdistrict, Kulon Progo Regency by geoelectric and microseismic methods. The research had been conducted after knowing the subsurface lithology conditions, it could anticipate landslides as disaster mitigation. The location of research is on a hillside in Purwoharjo Village. The research located on that area because the history landslides. The area is the longest landslide and had a major impact on the villagers that located below the hill. The research used a set of resistivity geoelectric devices with Syscal brands and microseismic devices Digital Portable Seismograph brands TDL-3035 type Taide brands. In geoelectric method used 5 lines, 2 lines 150 m from north to south, 2 lines 120 m and 1 line 100 m from east to west, while the microseismic method used 30 points with spaces of 10-100 meters. The results of the geoelectric method are obtained lithology of clay material with resistivity of 0.16 - 160 Ω.m, sand material with resistivity 160 - 1093 Ω.m, sandstone material with resistivity 1093 - 8000 Ω.m, and a andesite material with resistivity of 8000 - 122165 Ω.m, while the results of the microseismic method obtained clay rock material having a value of Vs between 406.33 m/s and 742.52 m/s represented by the dark blue spectrum. In the middle landslide has a depth of clay material up to 33 meters. The results showed that subsurface lithology in the area is prone to landslides, because it is suspected that there is a sliding field at a depth of 33 meters. This is supported by the presence of andesite rocks which spread at a depth of 20 meters and above the andesite material, there is clay material that quite thick.

Study on the spatio-temporal relationship between ground fracturing and underground drainage holes arrangement

Based on the respective technical advantages of ground fracturing and underground gas drainage, a joint drainage mode of ground wells and underground is proposed, which focuses on utilizing the large-scale advantages of ground fracturing to promote underground gas drainage. Experimental study of two kinds of ground fracturing and underground drainage connection Mode, that is “Ground fracturing lags behind drilling construction” and “drilling construction lags behind the ground fracturing”. Through the micro-seismic method and the underground hole exposure method, it is concluded that the cracks in the coal seam are mainly horizontal cracks with a small northeast opening, and the crack length is about 158~203m. According to the law of crack distribution, fracturing investigation schemes of two modes were designed. The reasonable time connection between the ground fracturing and underground drainage is preliminarily determined by the engineering practice, it is effective in increasing the permeability of the coal seam, reducing the abnormal gas emission from the coal seam and the risk of coal and gas outburst by using “ground fracturing lags behind drilling construction”; the gas drainage effect is remarkable when the underground drilling is delayed within 3 months of ground fracturing by using “drilling construction lags behind the ground fracturing”.

Landslide potency based on microseismic data-case study in Trangkil area Gunungpati, Semarang

A research using microseismic method had been conducted in Trangkil Sejahtera area, Semarang. Microseismic is an effective method to determine the ground shear strain value of a region. This study aimed to determine a landslide prone area within Trangkil Sejahtera, Semarang. Microseismic measurements was performed in an area of 200 × 400 metres with 9 points of measurements. Acquired data from the measurements was then analysed using HVSR (Horizontal to Vertical Spectrum Ratio) method, obtained the natural frequency value between 1.38-7.07 Hz, amplification between 1.42-3.28, thickness of weathering layer between 17.02-95.53 metres and ground shear strain value between 0.00083–0.00203. Those values were then mapped using Surfer to depict the distribution. Furthermore, by integrating the natural frequency value, amplification, Kg, PGA and GSS, it could be known that the landslide prone area is in the northern area of Trangkil Sejahtera.

Identification of landslide potential in Gajahmungkur village Semarang using ground shear strain analysis

The Gajahmungkur village, based on slope and geological structure, are included in the landslide potential category. Research of landslide hazard due to earthquake in weak zone can be done by ground shear strain analysis (GSS). This study aims to provide information related to the potential landslide disaster in the Gajahmungkur village of Semarang city. The data were collected using microseismic method. The research area is 42,000 m2 consisting of 12 points and 3 trajectories. Data processing is done using Software of Geopsy and Surfer to obtain the value of vulnerability index of subsurface ground, maximum ground acceleration value, and ground shear strain value. The result of data analysis shows that the research area at point 9, point 10, and point 12 has the value of vulnerability index which is much higher than the other point so that the value of ground shear strain in all three points is also high. The value of ground shear strain obtained at the order of 10−4 then the dynamic nature that occurs in the research points have a plastic character. This plastic characteristic characterizes the area as a landslide potential.

Microseismic research using coherence and cross-correlation in Depok, Sleman, Yogyakarta

Yogyakarta area is one of earthquake-prone area in Indoneis. It is include in the Indo-Australian plate subduction zone under the Eurasian plate. It also has an active fault, namely Opak fault that located in Bantul Regency.Microseismic method is one way that can be used to analyze soil vulnerability of earthquakes. The Microseismic method is a geophysical method that utilizes natural vibrations as its source. The data of the Microseismic Method is processed using HVSR Method. It is used to compare horizontal to vertical spectra ratio. The results of HVSR shows the value of the dominant frequency (f0), amplification (A0) the Soil Vulnerability Index (Kg).The results of this research that especially located in Depok District, Sleman Regency has the dominant frequency value that range from 0.65 to 1.35 Hz, amplification value between 2.6 and 5.6 and soil susceptibility value is 4-52 s2 / cm. The data obtained from the southern part of the research area, it shows that it has dominant frequency and high amplification values. To reassure the data, coherence graphs, phase velocity graphs and cross correlation maps were made between amplification maps with dominant frequencies, dominant frequency maps with topography, amplification maps with topography and maps of soil vulnerability index with topography. Coherence and correlation cross graphs show a small link to the south of the research area.

Prediction of rockburst in tunnels at the Jinping II hydropower station using microseismic monitoring technique

Rockburst hazards are frequently encountered in tunnels at the Jinping II hydropower station, which pose serious threats to the safety of personnel and equipment. Abnormal stress concentration caused by the rock mass interfaces and geological defects along the #3 headrace tunnel makes the rockburst difficult to predict using routine estimate and monitoring methods. A two-body interaction model was used to interpret the mechanism of the rockburst, which divided the evolution of a rockburst into three stages, i.e., the stress buildup period, early warning period, and rockburst occurrence period. The microseismic (MS) monitoring technique, which can capture the associated seismicity in the stress buildup period and early warning period, was employed to study and predict the rockburst hazards. An intense rockburst occurred at the right sidewall of the #3 headrace tunnel on September 21, 2011. The rockburst location was recognized by analyzing the spatial-temporal distribution and density contour plot of the recorded MS events from September 12, 2011 to September 21, 2011. Some seismic precursors to the rockburst were obtained based on quantitative interpretation of the source and statistical parameters of the 367 MS events, and they are a sharp increase in the daily event count and average energy level, the energy index remains at extremely high levels accompanied with a rapid increase in the cumulative apparent volume, a sharp decrease in the b value to an extremely low level, and a rapid increase in the seismicity index to an abnormally high level. The multi-parameter precursors to the rockburst should be comprehensively used to improve the prediction accuracy. The validity of using the MS method to predict the rockburst was verified by the preliminary achievement at the #3 headrace tunnel. This study may be valuable to improve the accuracy of rockburst prediction, and helpful for the safety assessment during construction of deep-buried tunnels.

Zonation of Landslide-Prone Using Microseismic Method and Slope Analysis in Margoyoso, Magelang

Margoyoso Village, Salaman Sub-district, Magelang Regency, Central Java is one of the villages that were included in landslide prone areas. The steep slopes and land use in this village were quite apprehensive. There were fractures with 5 cm in width and a length of 50 m. Moreover, these fractures appeared in the home residents. Although the local government has established a disaster response organization, this village is still not getting adequate information about the landslide prone areas. Based on the description before, we conducted research with geophysical methods and geotechnical analysis to minimize the danger of landslides. The geophysical method used in this research was microseismic method and geotechnical analysis. The microseismic measurement and slope stability analysis at Margoyoso village was a step in analysing the landslide-prone zone boundary. The results of this research indicated that landslide potential areas had a low peak ground acceleration values with a range from 36 gal to 46 gal. Measurement of slope stability indicated that a slope angle values between 55°-78° are a potential landslide slope because the soil in this village has very loose properties so it is very easy to move.

Unveiling the signals from extremely noisy microseismic data for high-resolution hydraulic fracturing monitoring

Microseismic method is an essential technique for monitoring the dynamic status of hydraulic fracturing during the development of unconventional reservoirs. However, one of the challenges in microseismic monitoring is that those seismic signals generated from micro seismicity have extremely low amplitude. We develop a methodology to unveil the signals that are smeared in the strong ambient noise and thus facilitate a more accurate arrival-time picking that will ultimately improve the localization accuracy. In the proposed technique, we decompose the recorded data into several morphological multi-scale components. In order to unveil weak signal, we propose an orthogonalization operator which acts as a time-varying weighting in the morphological reconstruction. The orthogonalization operator is obtained using an inversion process. This orthogonalized morphological reconstruction can be interpreted as a projection of the higher-dimensional vector. We first test the proposed technique using a synthetic dataset. Then the proposed technique is applied to a field dataset recorded in a project in China, in which the signals induced from hydraulic fracturing are recorded by twelve three-component (3-C) geophones in a monitoring well. The result demonstrates that the orthogonalized morphological reconstruction can make the extremely weak microseismic signals detectable.

Application of Downhole Micro-seismic Technique in Shale Gas Fracturing Optimization of Fuling, China

The downhole micro-seismic method has successfully applied to well fractory fracturing development in Jiaoshiba block, Fuling shale gas reservoir in September 2015. The new concept and understanding have accumulated. Combing the actual construction condition of micro-seismic monitoring in JY AA-BB well groups, we reviewed briefly the downhole micro-seismic monitoring technology and then summarized multi-disciplinary experience and understanding. The staged fracturing process level improved and productivity increased with the further development of shale gas field. Results show that the understanding of micro-seismic method has played a guiding role in the optimization of fracturing process and site construction adjustment of other wells in the same area, which increased the productivity and created a huge economic benefits with a broad market prospects.

Seismic Hazard Analysis based on Earthquake Vulnerability and Peak Ground Acceleration using Microseismic Method at Universitas Negeri Semarang

Microseismic is a harmonic vibration of land that occurs continuously at a low frequency. The characteristics of microseismic represents the characteristics of the soil layer based on the value of its natural frequency. This paper presents the analysis of seismic hazard at Universitas Negeri Semarang using microseismic method. The data acquisition was done at 20 points with distance between points 300 m by using three component’s seismometer. The data was processed using Horizontal to Vertical Spectral Ratio (HVSR) method to obtain the natural frequency and amplification value. The value of the natural frequency and amplification used to determine the value of the earthquake vulnerability and peak ground acceleration (PGA). The result shows then the earthquake vulnerability value range from 0.2 to 7.5, while the value of the average peak ground acceleration (PGA) is in the range 10-24 gal. Therefore, the average peak ground acceleration equal to earthquake intensity IV MMI scale.