scholarly journals Analysis of post-blasting source mechanisms of mining-induced seismic events in Rudna copper mine, Poland

2015 ◽  
Vol 4 (1) ◽  
pp. 26-38 ◽  
Author(s):  
Alicja Caputa ◽  
Adam Talaga ◽  
Łukasz Rudziński
Keyword(s):  
Underground Mining ◽  
Moment Tensor ◽  
Seismic Events ◽  
Rockburst Hazard ◽  
Mining Areas ◽  
Double Couple ◽  
Source Mechanisms ◽  
Dc Component ◽  
Full Moment Tensor ◽  
Stress Accumulation

Abstract The exploitation of georesources by underground mining can be responsible for seismic activity in areas considered aseismic. Since strong seismic events are connected with rockburst hazard, it is a continuous requirement to reduce seismic risk. One of the most effective methods to do so is blasting in potentially hazardous mining panels. In this way, small to moderate tremors are provoked and stress accumulation is substantially reduced. In this paper we present an analysis of post-blasting events using Full Moment Tensor (MT) inversion at the Rudna mine, Poland, underground seismic network. In addition, we describe the problems we faced when analyzing seismic signals. Our studies show that focal mechanisms for events that occurred after blasts exhibit common features in the MT solution. The strong isotropic and small Double Couple (DC) component of the MT, indicate that these events were provoked by detonations. On the other hand, post-blasting MT is considerably different than the MT obtained for strong mining events. We believe that seismological analysis of provoked and unprovoked events can be a very useful tool in confirming the effectiveness of blasting in seismic hazard reduction in mining areas.

Seismic source inversion using Hamiltonian Monte Carlo and a 3-D Earth model in the Japanese Islands

2020 ◽  
Author(s):  
Saulė Simutė ◽  
Lion Krischer ◽  
Christian Boehm ◽  
Martin Vallée ◽  
Andreas Fichtner
Keyword(s):  
Monte Carlo ◽  
Moment Tensor ◽  
Seismic Source ◽  
Monte Carlo Algorithm ◽  
Earth Model ◽  
Model Parameters ◽  
Hamiltonian Monte Carlo ◽  
Double Couple ◽  
Full Moment Tensor ◽  
Japanese Islands

<p>We present a proof-of-concept catalogue of full-waveform seismic source solutions for the Japanese Islands area. Our method is based on the Bayesian inference of source parameters and a tomographically derived heterogeneous Earth model, used to compute Green’s strain tensors. We infer the full moment tensor, location and centroid time of the seismic events in the study area.</p><p>To compute spatial derivatives of Green’s functions, we use a previously derived regional Earth model (Simutė et al., 2016). The model is radially anisotropic, visco-elastic, and fully heterogeneous. It was constructed using full waveforms in the period band of 15–80 s.</p><p>Green’s strains are computed numerically with the spectral-element solver SES3D (Gokhberg & Fichtner, 2016). We exploit reciprocity, and by treating seismic stations as virtual sources we compute and store the wavefield across the domain. This gives us a strain database for all potential source-receiver pairs. We store the wavefield for more than 50 F-net broadband stations (www.fnet.bosai.go.jp). By assuming an impulse response as the source time function, the displacements are then promptly obtained by linear combination of the pre-computed strains scaled by the moment tensor elements.</p><p>With a feasible number of model parameters and the fast forward problem we infer the unknowns in a Bayesian framework. The fully probabilistic approach allows us to obtain uncertainty information as well as inter-parameter trade-offs. The sampling is performed with a variant of the Hamiltonian Monte Carlo algorithm, which we developed previously (Fichtner and Simutė, 2017). We apply an L2 misfit on waveform data, and we work in the period band of 15–80 s.</p><p>We jointly infer three location parameters, timing and moment tensor components. We present two sets of source solutions: 1) full moment tensor solutions, where the trace is free to vary away from zero, and 2) moment tensor solutions with the isotropic part constrained to be zero. In particular, we study events with significant non-double-couple component. Preliminary results of ~Mw 5 shallow to intermediate depth events indicate that proper incorporation of 3-D Earth structure results in solutions becoming more double-couple like. We also find that improving the Global CMT solutions in terms of waveform fit requires a very good 3-D Earth model and is not trivial.</p>

Source mechanism of recent seismic events and microzonation studies along Sagaing Fault near Nay Pyi Taw, capital of Myanmar

2020 ◽  
Author(s):  
Claus Milkereit ◽  
Pa Pa Tun ◽  
Oo Than ◽  
Kyawmoe Oo ◽  
Kyaw Zayar Naing ◽  
...  
Keyword(s):  
Moment Tensor ◽  
Geological Mapping ◽  
Seismic Events ◽  
Precise Location ◽  
International Agencies ◽  
Shallow Earthquakes ◽  
First Results ◽  
Source Mechanisms ◽  
Distinct Frequency ◽  
Ongoing Project

<p>In 2005, the capital of Myanmar was moved to the newly designed city of Nay Pyi Taw, some 300 km north of Yangon. Both Yangon as well as the capital Nay Pyi Taw are situated along the 1200 km long north-south trending Sagaing Fault, an active strike-slip fault which showed large and disastrous earthquakes in the past. Almost nothing is known about details of the Sagaing Fault in the area of Nay Pyi Taw, neither the precise location of different branches of the Sagaing Fault, nor the precise location of recent seismic events along different branches of the fault, nor the distribution and depth of the sedimentary layers in and around Nay Pyi Taw.</p><p>Since 2014, 4 shallow earthquakes with magnitudes larger than ML=4 are reported near Nay Pyi Taw. Some were clearly felt in the capital. The different location solutions reported by local and international agencies indicate a location accuracy not better accurate than 5 km. We derived re-locations and moment tensor analyses as well as meaningful model uncertainties for these events. The results show that the Sagaing Fault near Nay Pyi Taw may follow different active branches. While geological mapping indicates an active branch west of Nay Pyi Taw, the event locations and source mechanisms of the recent seismic activity indicate an active branch under and east of Nay Pyi Taw. Here, a geological mapping is complicated as sediments of unknown thickness cover the basement. Therefore, a microzonation study has been started with the aim to determine the fundamental resonant frequencies of the sedimentary layers, their spatial variability, and the amplification factors. First results of this ongoing project with more than 50 noise recordings in and around Nay Pyi Taw indicate amplification of ground motion with a factor up to 10 in distinct frequency ranges from 0.3 – 10 Hz.</p><p> </p>

scholarly journals An MCMC Bayesian full moment tensor inversion constrained by first-motion polarities and double couple percent

2020 ◽  
Author(s):  
Mehrdad Pakzad ◽  
Mahnaz Khalili ◽  
Shaghayegh Vahidravesh
Keyword(s):  
Moment Tensor ◽  
Waveform Inversion ◽  
Model Parameters ◽  
Mcmc Method ◽  
Posterior Probability Density ◽  
Double Couple ◽  
First Motion ◽  
Bayesian Mcmc Method ◽  
Full Moment Tensor ◽  
Large Earthquakes

Abstract. Monte Carlo Markov chain (MCMC) samplings can obtain a set of samples by directed random walk, mapping the posterior probability density of the model parameters in Bayesian framework. We perform earthquake waveform inversion to retrieve focal angles or the elements of moment tensor and source location using a Bayesian MCMC method with the constraints of first-motion polarities and double couple percentage using full Green functions and data covariance matrix. The algorithm tests the compatibility with polarities and also checks the double couple percentage of every site before the time-consuming synthetic seismogram computation for every sample of moment tensor of every trial source position. Other than large earthquakes, the method is especially suitable for weak events (M 

Uncertainties in Seismic Moment Tensors Inferred from Differences between Global Catalogs

2021 ◽  
Author(s):  
Boris Rösler ◽  
Seth Stein ◽  
Bruce D. Spencer
Keyword(s):  
Moment Tensor ◽  
Centroid Moment Tensor ◽  
Moment Tensors ◽  
Double Couple ◽  
Source Mechanisms ◽  
Order Of Magnitude ◽  
The Difference ◽  
The Moment ◽  
Source Geometry ◽  
Scalar Moment

Abstract Catalogs of moment tensors form the foundation for a wide variety of seismological studies. However, assessing uncertainties in the moment tensors and the quantities derived from them is difficult. To gain insight, we compare 5000 moment tensors in the U.S. Geological Survey (USGS) and the Global Centroid Moment Tensor (Global CMT) Project catalogs for November 2015–December 2020 and use the differences to illustrate the uncertainties. The differences are typically an order of magnitude larger than the reported errors, suggesting that the errors substantially underestimate the uncertainty. The catalogs are generally consistent, with intriguing differences. Global CMT generally reports larger scalar moments than USGS, with the difference decreasing with magnitude. This difference is larger than and of the opposite sign from what is expected due to the different definitions of the scalar moment. Instead, the differences are intrinsic to the tensors, presumably in part due to different phases used in the inversions. The differences in double-couple components of source mechanisms and the fault angles derived from them decrease with magnitude. Non-double-couple (NDC) components decrease somewhat with magnitude. These components are moderately correlated between catalogs, with correlations stronger for larger earthquakes. Hence, small earthquakes often show large NDC components, but many have large uncertainties and are likely to be artifacts of the inversion. Conversely, larger earthquakes are less likely to have large NDC components, but these components are typically robust between catalogs. If so, these can indicate either true deviation from a double couple or source complexity. The differences between catalogs in scalar moment, source geometry, or NDC fraction of individual earthquakes are essentially uncorrelated, suggesting that the differences reflect the inversion rather than the source process. Despite the differences in moment tensors, the location and depth of the centroids are consistent between catalogs. Our results apply to earthquakes after 2012, before which many moment tensors were common to both catalogs.

scholarly journals Full moment tensor inversion constrained by double-couple focal mechanism for induced seismicity

2020 ◽  
Vol 33 (4) ◽  
pp. 177-193
Author(s):  
Yuyang Tan ◽  
◽  
Haijiang Zhang ◽  
Junlun Li ◽  
Chen Yin ◽  
...  
Keyword(s):  
Focal Mechanism ◽  
Induced Seismicity ◽  
Moment Tensor ◽  
Moment Tensor Inversion ◽  
Double Couple ◽  
Full Moment Tensor

Dense surface seismic data confirm non-double-couple source mechanisms induced by hydraulic fracturing

Geophysics ◽  
2016 ◽  
Vol 81 (6) ◽  
pp. KS207-KS217 ◽  
Author(s):  
Jeremy D. Pesicek ◽  
Konrad Cieślik ◽  
Marc-André Lambert ◽  
Pedro Carrillo ◽  
Brad Birkelo
Keyword(s):  
Hydraulic Fracturing ◽  
Seismic Data ◽  
P Wave ◽  
Source Modeling ◽  
Moment Tensors ◽  
Amplitude Data ◽  
Double Couple ◽  
Source Mechanisms ◽  
Source Models ◽  
Favorable Conditions

We have determined source mechanisms for nine high-quality microseismic events induced during hydraulic fracturing of the Montney Shale in Canada. Seismic data were recorded using a dense regularly spaced grid of sensors at the surface. The design and geometry of the survey are such that the recorded P-wave amplitudes essentially map the upper focal hemisphere, allowing the source mechanism to be interpreted directly from the data. Given the inherent difficulties of computing reliable moment tensors (MTs) from high-frequency microseismic data, the surface amplitude and polarity maps provide important additional confirmation of the source mechanisms. This is especially critical when interpreting non-shear source processes, which are notoriously susceptible to artifacts due to incomplete or inaccurate source modeling. We have found that most of the nine events contain significant non-double-couple (DC) components, as evident in the surface amplitude data and the resulting MT models. Furthermore, we found that source models that are constrained to be purely shear do not explain the data for most events. Thus, even though non-DC components of MTs can often be attributed to modeling artifacts, we argue that they are required by the data in some cases, and can be reliably computed and confidently interpreted under favorable conditions.

A teleseismic body-wave analysis of the May 1980 Mammoth Lakes, California, earthquakes

1983 ◽  
Vol 73 (2) ◽  
pp. 419-434
Author(s):  
Jeffery S. Barker ◽  
Charles A. Langston
Keyword(s):  
Body Wave ◽  
Moment Tensor ◽  
Normal Fault ◽  
Strike Slip ◽  
Body Waves ◽  
P Wave ◽  
Moment Tensors ◽  
Double Couple ◽  
The Moment ◽  
Mammoth Lakes

abstract Teleseismic P-wave first motions for the M ≧ 6 earthquakes near Mammoth Lakes, California, are inconsistent with the vertical strike-slip mechanisms determined from local and regional P-wave first motions. Combining these data sets allows three possible mechanisms: a north-striking, east-dipping strike-slip fault; a NE-striking oblique fault; and a NNW-striking normal fault. Inversion of long-period teleseismic P and SH waves for the events of 25 May 1980 (1633 UTC) and 27 May 1980 (1450 UTC) yields moment tensors with large non-double-couple components. The moment tensor for the first event may be decomposed into a major double couple with strike = 18°, dip = 61°, and rake = −15°, and a minor double couple with strike = 303°, dip = 43°, and rake = 224°. A similar decomposition for the last event yields strike = 25°, dip = 65°, rake = −6°, and strike = 312°, dip = 37°, and rake = 232°. Although the inversions were performed on only a few teleseismic body waves, the radiation patterns of the moment tensors are consistent with most of the P-wave first motion polarities at local, regional, and teleseismic distances. The stress axes inferred from the moment tensors are consistent with N65°E extension determined by geodetic measurements by Savage et al. (1981). Seismic moments computed from the moment tensors are 1.87 × 1025 dyne-cm for the 25 May 1980 (1633 UTC) event and 1.03 × 1025 dyne-cm for the 27 May 1980 (1450 UTC) event. The non-double-couple aspect of the moment tensors and the inability to obtain a convergent solution for the 25 May 1980 (1944 UTC) event may indicate that the assumptions of a point source and plane-layered structure implicit in the moment tensor inversion are not entirely valid for the Mammoth Lakes earthquakes.

scholarly journals KAMCHATKA AND COMMANDER ISLANDS

2020 ◽  
pp. 172-182
Author(s):  
D. Chebrov ◽  
A. Chebrova ◽  
I. Abubakirov ◽  
E. Matveenko ◽  
S. Mityushkina ◽  
...  
Keyword(s):  
Moment Tensor ◽  
Seismic Intensity ◽  
Earthquake Catalogue ◽  
Seismic Moment Tensor ◽  
Magnitude Of Completeness ◽  
Commander Islands ◽  
Strong Earthquakes ◽  
Double Couple ◽  
Kamchatka Earthquake ◽  
Surrounding Areas

The seismicity review of Kamchatka and surrounding territories for 2014 is given. In Kamchatka earthquake catalogue minimum local magnitude of completeness is MLmin=3.5, and for earthquakes under the Okhotsk sea with h≥350 kmMLmin=3.6. The Kamchatka earthquake catalogue for 2014 with ML3.5, published in the Appendix to this annual, includes 1114 events. 86 earthquakes of the catalogue with ML=3.35–6.2 were felt in Kamchatka and surrounding areas with seismic intensity I ranged from 2 to 5 according the MSK-64 scale. For all events with ML5.0 occurred in the area of responsibility of the KB GS RAS in 2014, an attempt to calculate the seismic moment tensor (SMT) was made. There are 40 such events in the regional catalogue. For 36 earthquakes, the SMT and depth h of the equivalent point source were calculated successfully. The calcu-lations were performed for the SMT double-couple model using a nonlinear algorithm. In 2014, a typical location of the earthquake epicenters was observed in the Kamchatka zone. In 2014, the seismicity level in all selected zones and in the region as a whole corresponded to the background one according to the “SESL’09” scale. The number of recorded events with ML3.6 and strong earthquakes with ML5.1 is close to the average annual value. Anomalous and outstanding events were not recorded.

scholarly journals Assesment Work Fatigue To Workers In Environment Underground Mining Areas Based On Fatigue Assesment Scale Questionnaires

2020 ◽  
Vol 202 ◽  
pp. 05013
Author(s):  
Siti Rachmawati ◽  
Miftaqul Aktsari ◽  
Anis Suryaningsih ◽  
Hashfi Hawali Abdul Matin ◽  
Iwan Suryadi
Keyword(s):  
Rating Scale ◽  
Underground Mining ◽  
Sleep Time ◽  
Type Ii ◽  
Work Time ◽  
Fatigue Assessment ◽  
Mining Areas ◽  
Hours Of Work ◽  
Fatigue Evaluation ◽  
Descriptive Method

Fatigue is recognized as a high potential risk for accidents and therefore an assessment of work fatigue is required. The purpose of this study is to describe the overall work fatigue assessment and based on work fatigue factors using questionnaires for the fatigue rating scale for workers in underground mining areas. This study used a descriptive method to describe the overall assessment of work fatigue and assessment of work fatigue based on factors related to fatigue using questionnaire scale fatigue assessment of workers in underground mining areas at PT. Y. Overall fatigue assessment based on fatigue evaluation questionnaire results obtained 54.55% of workers who experience fatigue. Fatigue assessment based on factors related to work fatigue shows that workers who tend to experience fatigue are> 45 years of age, <7 hours of sleep,> 5 years of work, 12 hours of work, supervisor type II / jumbo operator drill, jumbo drill operator, LHD operator, and service crew / helper jumbo drill, work climate> NAB (> 29.00 C) and noise> NAB (> 85 dB A). Underground mining workers tend to experience fatigue. The older the worker's age, the less sleep time, the longer the work period, the longer work time, the heavier the type of work, the hotter the working climate and the noisier it tends to experience fatigue.

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