Source mechanism of mining induced seismic events — Resolution of double couple and non double couple models

2008 ◽  
Vol 456 (1-2) ◽  
pp. 3-15 ◽  
Author(s):  
Jan Šílený ◽  
Alexander Milev
Keyword(s):  
Source Mechanism ◽  
Seismic Events ◽  
Double Couple ◽  
Couple Models

Simultaneous microseismic event localization and source mechanism determination

Geophysics ◽  
2015 ◽  
Vol 80 (1) ◽  
pp. KS1-KS9 ◽  
Author(s):  
Oksana Zhebel ◽  
Leo Eisner
Keyword(s):  
Oil And Gas ◽  
Signal To Noise Ratio ◽  
Moment Tensor ◽  
Microseismic Monitoring ◽  
Primary Objective ◽  
Gas Production ◽  
Source Mechanism ◽  
Seismic Events ◽  
Near Surface ◽  
Microseismic Event

Microseismic monitoring has become a tool of choice for the development and optimization of oil and gas production from unconventional reservoirs. The primary objective of (micro) seismic monitoring includes localization of (micro) seismic events and characterization of their source mechanisms. Most seismic events are of a nonexplosive nature, and thus, there are waveform (polarity) differences among receivers. Specifically, double-couple sources represented a challenge for migration-based localization techniques. We developed and applied a new migration-type location technique combined with source mechanism inversion that allowed for constructive interference of signal in seismic waveforms. The procedure included constructing image functions by stacking the amplitudes with compensated polarity changes. The compensation weights were calculated by using moment tensor inversion. This method did not require any picking of arrivals at individual receivers, but it required receivers to be distributed in multiple azimuths and offsets. This made the technique suitable for surface or near-surface monitoring, in which a low signal-to-noise ratio (S/N) can be overcome by stacking. Furthermore, the advantage of this technique was that in addition to the position in time and space, we also determined the source mechanism. We determined with numerical tests that the proposed technique can be used for detection and location of events with S/Ns as low as 0.05 at individual (prestacked) receivers. Furthermore, we found that other source mechanism parameters such as magnitude, volumetric, or shear components of the source mechanism were not suitable for the location. Finally, we applied the proposed technique to a microseismic event of moment magnitude [Formula: see text] induced during the hydraulic fracturing treatment of a gas shale reservoir in North America.

Radiation pattern of mantle Rayleigh waves and the source mechanism of the Hindu Kush earthquake of July 6, 1962

1965 ◽  
Vol 55 (5) ◽  
pp. 805-819 ◽  
Author(s):  
Ramesh Chander ◽  
James N. Brune
Keyword(s):  
Rayleigh Waves ◽  
Focal Depth ◽  
Point Sources ◽  
The Body ◽  
P Wave ◽  
Source Mechanism ◽  
Radiation Patterns ◽  
Wave Data ◽  
Hindu Kush ◽  
Double Couple

abstract The source mechanism of the Hindu Kush earthquake of July 6, 1962 (magnitude 634-7, focal depth 218 km) was studied by comparing the observed amplitude and phase radiation patterns of mantle Rayleigh waves of 150 sec and 200 sec period with theoretical radiation patterns of Rayleigh waves from single- and double-couple point sources, and by considering evidence from Love waves and the shape of P and S pulses. The solution for the source mechanism, which is consistent with all the body wave and surface wave data available for this earthquake, is a double couple acting as a step function in time, with nodal planes oriented as determined from P wave data. Since for waves with periods greater than about 5 sec, the source appears to be an ideal point source, the radius of the equivalent source volume is estimated to be less than 10 km. For Rayleigh waves of 150 sec period, the agreement between observed and theoretical phases (for the above source model) is greatly improved by assuming regional phase velocities instead of a uniform phase velocity for all areas. It is concluded that with the accuracy currently attainable, a study of Rayleigh waves alone cannot determine the source mechanism of an earthquake uniquely.

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.

Shallow seismic events with combined source mechanism

1988 ◽  
Vol 152 (3-4) ◽  
pp. 283-296 ◽  
Author(s):  
Jan Šílený ◽  
Jan Kozák
Keyword(s):  
Source Mechanism ◽  
Seismic Events ◽  
Shallow Seismic

Source-mechanism from spectra of long-period seismic surface waves.

1963 ◽  
Vol 53 (5) ◽  
pp. 905-919 ◽  
Author(s):  
Ari Ben-Menahem ◽  
M. Nafi Toksöz
Keyword(s):  
Step Function ◽  
Source Mechanism ◽  
Aftershock Distribution ◽  
The Press ◽  
Seismic Surface Waves ◽  
Double Couple ◽  
T Phase ◽  
Phase Spectra ◽  
Fault Length ◽  
Good Agreement

Abstract Source-mechanism is derived from amplitude and phase spectra of mantle Love and Rayleigh waves of the Alaska earthquake of July 10, 1958. The signals R2, R3, G2, G4, G5 recorded on the Gilman 80–90 and the Press-Ewing 30–90 seismograph systems at Pasadena, California, are separated, digitized, filtered and Fourier-analyzed. An agreement between theory and observations is obtained for a unilateral fault of 300–350 km, which ruptured with a speed of 3-3.5 km/sec in the direction N40°W. Fault length is in good agreement with the extent of aftershock distribution in the month of July, 1958, and the time of rupture checks with the duration of an impressive T-phase recorded at Hawaii. The phases of the signals are corrected for propagation, instrumental shift and the source finiteness. Initial phases thus obtained agree on a mechanism of a right double-couple with a unit step-function in time.

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