scholarly journals An approach to assessment of post mining-induced seismic hazard in Kolar Gold Fields mines – a review

2021 ◽  
Vol 69 (3) ◽  
pp. 88
Author(s):  
Praveena Das Jennifer ◽  
P. Porchelvan
Keyword(s):  
Seismic Hazard ◽  
Induced Seismicity ◽  
Seismic Vulnerability ◽  
Source Parameters ◽  
Seismic Source ◽  
Mining Area ◽  
Mining Induced Seismicity ◽  
Ground Collapse ◽  
Term Monitoring

A common challenge faced in underground hardrock mines worldwide is post mining-induced seismicity, as the events have been quite disastrous, causing risk to the structures and lives. In the recent years, many of the worked out mining areas are slowly getting populated and in due course of time shall be posing environmental threat to the people residing above and to the surface structures like sudden void formations or sudden ground collapse becoming visible on the surface. Worked out or closed mines have most of the time shown existence of post mining-induced seismicity signatures. Some of the closed mines showing post mining induced seismicity in Korea, South Africa, Sweden and India are being discussed. Post mining induced seismicity observed in Kolar Gold Fields worked out mine still being felt since closure of deeper levels is discussed. As mining depth increases especially in hard rock mines, magnitude of stress increases, hence, the occurrence and severity of postmining induced seismicity also increases. The problem becomes more serious if proper fund allocation is not done to investigate these areas, may be due to the absence of economic interest once the mine site has been abandoned and in many cases, direct investigations inside the mines may not be possible due to stability problems or due to the ingress of water into the void spaces of the mining area. Several approaches and techniques adopted by researcher’s world over are being discussed in this paper, with a view to gaining insight into the techniques of evaluation of seismic hazard. Seismic vulnerability assessment should integrate the effects of all the seismic events occurring at different locations of mining area during mining and post mining, along with their uncertainties also being considered. Based on the recorded data and some of the derived parameters from previous years, an attempt should be made to evaluate the existing risk prone areas. The past records of induced seismicity due to mining should be used as a precursor for identification of impending future events and their expected probable locations of occurrence. The methods discussed here for assessment of seismic hazard are based on direct waveform and seismic source parameters, parameters from indirect waveform methods, frequency-magnitude relationship based, and frequency content analysis based. From the assessment it is found that the choice of method that can be used depends on the period of monitoring (short-term monitoring, intermediate-term or long-term monitoring) and the objective of the study required to be achieved, this varies on site-to-site basis. The main focus is to show the importance and need to install a micro seismic monitoring system for long term assessment of seismic risk especially in abandoned/worked out mines showing post mining-induced seismicity.

scholarly journals Seismic hazard maps of Peshawar District for various return periods

2020 ◽  
Vol 20 (6) ◽  
pp. 1639-1661
Author(s):  
Khalid Mahmood ◽  
Naveed Ahmad ◽  
Usman Khan ◽  
Qaiser Iqbal
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Target Location ◽  
Epistemic Uncertainty ◽  
Hazard Analysis ◽  
Source Parameters ◽  
Seismic Source ◽  
Return Periods ◽  
Hazard Maps ◽  
Seismic Hazard Maps

Abstract. Probabilistic seismic hazard analysis of Peshawar District has been performed for a grid size of 0.01∘. The seismic sources for the target location are defined as the area polygon with uniform seismicity. The earthquake catalogue was developed based on the earthquake data obtained from different worldwide seismological networks and historical records. The earthquake events obtained at different magnitude scales were converted into moment magnitude using indigenous catalogue-specific regression relationships. The homogenized catalogue was subdivided into shallow crustal and deep-subduction-zone earthquake events. The seismic source parameters were obtained using the bounded Gutenberg–Richter recurrence law. Seismic hazard maps were prepared for peak horizontal acceleration at bedrock level using different ground motion attenuation relationships. The study revealed the selection of an appropriate ground motion prediction equation is crucial for defining the seismic hazard of Peshawar District. The inclusion of deep subduction earthquakes does not add significantly to the seismic hazard for design base ground motions. The seismic hazard map developed for shallow crustal earthquakes, including also the epistemic uncertainty, was in close agreement with the map given in the Building Code of Pakistan Seismic Provisions (2007) for a return period of 475 years on bedrock. The seismic hazard maps for other return periods i.e., 50, 100, 250, 475 and 2500 years, are also presented.

scholarly journals Seismic hazard maps of Peshawar district for various return periods

2019 ◽  
Author(s):  
Khalid Mahmood ◽  
Usman Khan ◽  
Qaiser Iqbal ◽  
Naveed Ahmad
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Target Location ◽  
Epistemic Uncertainty ◽  
Source Parameters ◽  
Seismic Source ◽  
Return Periods ◽  
Hazard Maps ◽  
Earthquake Catalogues ◽  
Seismic Hazard Maps

Abstract. The probabilistic seismic hazard analysis of Peshawar District has been conducted in for a grid size of 0.01. The seismic sources for the target location are defined as the area polygon with uniform seismicity for which, the earthquake catalogues were obtained from different worldwide seismological network data. The earthquake catalogues obtained in different magnitude scale was converted into moment magnitude using regression analysis. The homogenized catalogue was then further subdivided into shallow crustal and deep subduction zone earthquake events for which, the seismic source parameters were obtained using Bounded Gutenberg-Richter Recurrence law. The seismic hazard maps were prepared in term of PGA at bedrock using the different ground motion attenuation relationships. The study shows that; the selection of appropriate ground motion prediction equation is an important factor in deciding the seismic hazard of Peshawar District. The inclusion of deep subduction earthquake does not add significantly to the seismic hazard. The calculated seismic hazard map for shallow crustal earthquake after including the epistemic uncertainty was in close agreement to that developed by BCP-2007 for a return period of 475 years on bedrock. The seismic hazard maps for other return periods i.e., 50, 100, 250, 475 and 2500 years were then prepared.

scholarly journals Persistent shallow micro-seismicity at Llaima volcano, Chile, with implications for long-term monitoring

2021 ◽  
Author(s):  
Oliver Lamb ◽  
Jonathan Lees ◽  
Luis Franco Marin ◽  
Jonathan Lazo ◽  
Andrés Rivera ◽  
...  
Keyword(s):  
Seismic Data ◽  
Low Frequency ◽  
Monitoring Network ◽  
Seismic Source ◽  
Atmospheric Temperature ◽  
Strongly Correlated ◽  
Source Mechanisms ◽  
Llaima Volcano ◽  
Term Monitoring

Identifying the source mechanisms of low-frequency earthquakes at ice-covered volcanoes can be challenging due to overlapping characteristics of glacially and magmatically derived seismicity. Here we present an analysis of two months of seismic data from Llaima volcano, Chile, recorded by the permanent monitoring network in 2019. We find over 2,000 repeating low-frequency events split across 82 families, the largest of which contains over 200 events. Estimated locations for the largest families indicate shallow sources directly beneath or near the edge of glaciers around the summit vent. These low-frequency earthquakes are part of an annual cycle in activity at the volcano that is strongly correlated with variations in atmospheric temperature, leading us to conclude that meltwater from ice and snow strongly affects the seismic source mechanisms which is likely dominated by basal slip beneath the glaciers. The results presented here should inform future assessments of eruptive potential at Llaima volcano, as well as other ice-covered volcanoes in Chile and worldwide.

scholarly journals Identification of the ground movements caused by mining-induced seismicity with the satellite interferometry

2020 ◽  
Vol 382 ◽  
pp. 297-301
Author(s):  
Ryszard Hejmanowski ◽  
Wojciech T. Witkowski ◽  
Artur Guzy ◽  
Agnieszka Malinowska
Keyword(s):  
Rock Mass ◽  
Induced Seismicity ◽  
Mining Area ◽  
Ground Movements ◽  
Mining Induced Seismicity ◽  
Rock Mass Deformation ◽  
Surface Vibrations ◽  
Satellite Radar ◽  
The Impact ◽  
Total Subsidence

Abstract. The assessment of the impact of mining-induced seismicity on the natural environment and infrastructure is often limited to the analysis of terrain surface vibrations. However, similar seismic phenomena, like earthquakes, may also imply dislocations and deformations of the rock mass. Such ground movements may occur in areas which are not directly under the influence of the mining. The study of the displacement field caused by mining-induced seismicity is usually carried out with the use of geodetic methods. Classical geodetic measurements provide discrete information about observed ground movements. As a result, they generally do not provide spatially and temporally relevant estimates of the total range and values of ground movements for specific periods of interest. Moreover, mining-induced seismicity causes a severe threat to buildings. That is why, regarding the complexity of the mechanism of occurrence of mining-induced seismicity and their impact on ground movements, this problem remains a substantial research issue. The presented research aimed to analyse the ground movements caused by mining-induced seismicity. The ground displacements were established based on data from Sentinel-1 satellites applying differential interferometric synthetic aperture radar (DInSAR). The results of the investigation in the copper mining area of the Lower Silesia region of Poland revealed that the observed subsidence caused by mining-induced seismicity usually has a shape of a regular ellipse. The radius of these ground movements does not exceed approximately 2–3 km from the mining-induced tremor's epicenter, and the total subsidence reaches ca. 10–20 cm. More than 50 % of the total subsidence is observed on the surface within a few days after the mining tremor occurrence. Furthermore, the deformations of the surface occur when the energy of mining-induced tremor reaches values of the order of 105 J or higher. The presented research can contribute to better identification and evaluation of the mechanism of the rock mass deformation process caused by mining-induced seismicity. In addition, the use of satellite radar interferometry improves the quality of monitoring of these dynamic phenomena significantly. The data retrieved using this method allow for quasi-continuous monitoring of the local subsidence bowls caused by mining-induced seismicity.

Preliminary Volcanic Seismic Hazard Analysis for Tatun Volcano Group in Northern Taiwan

2013 ◽  
Vol 479-480 ◽  
pp. 1061-1065
Author(s):  
Cheng Yu Pan ◽  
Yuan Cheih Wu ◽  
Chih Wei Chang
Keyword(s):  
Seismic Hazard ◽  
Power Plants ◽  
Hot Spring ◽  
Hazard Analysis ◽  
Source Parameters ◽  
Seismic Source ◽  
Seismic Hazard Analysis ◽  
Earthquake Catalog ◽  
Source Characterization ◽  
Taipei Basin

Tatun volcano group is located in north Taiwan and near Taipei Basin where several million people live there. Although it provides hot spring and landscape for citizens and keeps calm most of time, the threat remains, particularly for the two nearby nuclear power plants. This paper discusses the seismic hazard of volcanic seismic source including source characterization of Tatun volcano group, probabilistic seismic hazard analysis (PSHA), and its preliminary seismic hazard result. Based on nuclear regulatory requirement for PSHA, the uncertainties of source parameters are vital, such as geometry, maximum earthquake, and activity relating earthquake catalog selection, so the first-time seismic source characterization workshop for volcano is held to let domestic experts discuss their hypotheses and investigation result. Hence, the renewed source parameters can represent current geo-science for Tatun volcanic seismic source, and the process of PSHA can lead the better way to combine the result of different research projects for Tatun volcano.

Geomechanical modeling of induced seismicity source parameters and implications for seismic hazard assessment

Geophysics ◽  
2013 ◽  
Vol 78 (1) ◽  
pp. KS25-KS39 ◽  
Author(s):  
Bettina P. Goertz-Allmann ◽  
Stefan Wiemer
Keyword(s):  
Seismic Hazard ◽  
Pore Pressure ◽  
Stress Drop ◽  
Induced Seismicity ◽  
Critical Stress ◽  
Source Parameters ◽  
Differential Stress ◽  
Geomechanical Properties ◽  
Stress Changes ◽  
Stress States

We simulate induced seismicity within a geothermal reservoir using pressure-driven stress changes and seismicity triggering based on Coulomb friction. The result is a forward-modeled seismicity cloud with origin time, stress drop, and magnitude assigned to each individual event. Our model includes a realistic representation of repeating event clusters, and is able to explain in principle the observation of reduced stress drop and increased [Formula: see text]-values near the injection point where pore-pressure perturbations are highest. The higher the pore-pressure perturbation, the less critical stress states still trigger an event, and hence the lower the differential stress is before triggering an event. Less-critical stress states result in lower stress drops and higher [Formula: see text]-values, if both are linked to differential stress. We are therefore able to establish a link between the seismological observables and the geomechanical properties of the source region and thus a reservoir. Understanding the geomechanical properties is essential for estimating the probability of exceeding a certain magnitude value in the induced seismicity and hence the associated seismic hazard of the operation. By calibrating our model to the observed seismicity data, we can estimate the probability of exceeding a certain magnitude event in space and time and study the effect of injection depth and crustal strength on the induced seismicity.

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