Azimuthal variation of radiation of seismic energy from cast blasts
- Los Alamos National Lab., NM (United States)
- Thunder Basin Coal Co., Wright, WY (United States)
As part of a series of seismic experiments designed to improve the understanding of the impact of mining blasts on verifying a Comprehensive Test Ban Treaty, a sixteen station network of three-component seismic sensors were deployed around a large cast shot in the Black Thunder Mine. The seismic stations were placed, where possible, at a range of 2.5 kilometers with a constant inter-station spacing of 22.5 degrees. All of the data were recorded with the seismometers oriented such that the radial component pointed to the middle point of the approximately 2 kilometer long shot. High quality data were recorded at each station. Data were scaled to a range of 2.5 kilometers and the sum of the absolute value of the vertical, radial, and transverse channels computed. These observations were used to construct radiation patterns of the seismic energy propagating from the cast shot. It is obvious that cast shots do not radiate seismic energy isotropically. Most of the vertical motion occurs behind the highwall while radial and transverse components of motion are enhanced in directions parallel to the highwall. These findings have implications for local (0.1 to 15 kilometer range) and possibly for regional (100 to 2,000 kilometer range) seismic observations of cast blasting. Locally, it could be argued that peak particle velocities could be scaled not only by range but also by azimuthal direction from the shot. This result implies that long term planning of pit orientation relative to sensitive structures could mitigate problems with vibration levels from future blasting operations. Regionally, the local radiation pattern may be important in determining the magnitude of large scale cast blasts. Improving the transparency of mining operations to international seismic monitoring systems may be possible with similar considerations.
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 432903
- Report Number(s):
- LA-UR--96-4626; CONF-970253--1; ON: DE97001676
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
35 ARMS CONTROL
45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
COAL MINING
EXPLOSIVE FRACTURING
NON-PROLIFERATION TREATY
NUCLEAR EXPLOSIONS
PATTERN RECOGNITION
SEISMIC EFFECTS
SEISMIC WAVES
SURFACE EXPLOSIONS
SURFACE MINING
UNDERGROUND EXPLOSIONS
VERIFICATION
WAVE PROPAGATION