Source Phenomenology Experiments in Arizona

Abstract

The Source Phenomenology Experiments (SPE) were conducted at mines in northeastern and southeastern Arizona in the summer of 2003. The Arizona experiments have resulted in an important dataset for the nuclear monitoring community by providing data to address a number of source parameter issues. We designed, detonated, and recorded ten single-fired explosions at a copper mine in southeast Arizona and nine single-fired explosions in a northern Arizona coal mine. The single-fired explosions ranged in size from 200 to ~33000 lbs. of a mixture of Ammonium Nitrate Fuel Oil (ANFO) and emulsion explosives. Delay-fired mining explosions at each mine were also recorded. The explosions were recorded by hundreds of seismic instruments deployed at local and regional distances in addition to permanent regional broadband stations.Using this large dataset, we developed velocity models of the Black Mesa basin, Colorado Plateau, and southern Arizona for moment tensor inversion. Detailed refraction surveys were conducted at the mine test sites in order to determine the P-and S-wave velocities of the test beds and layer thicknesses. We used local single-component geophones (Texans) and regional broadband stations to study the P-wave velocity structure of the upper crust. Rg dispersion curves were extracted from the single-component local (<15 km) data and we inverted the data for S-wave velocity structure of the test pit region and upper crust. We also performed a joint inversion of surface wave dispersion and receiver functions to constrain the structure of the middle and lower crust.By inverting near-source broadband data, we developed time-dependent source moment tensors for several explosions detonated during the SPE. The results show that isotropic components dominate the moment tensors, especially for the contained explosions. Vented explosions have moment-tensor spectra that are more peaked than those of fully contained explosions. Moment tensors of cast blasts show a certain amount of longer-period laterarriving energy for off-diagonal components, which is responsible for most of the shear energy generated.We examined the regional discrimination of the SPE shots relative to normal production mining explosions, natural earthquakes, and previous nuclear tests at the Nevada Test Site. The discrimination analysis includes identifying and picking the onset times of the regional phases Pn, Pg, and Lg, making amplitude measurements in a variety of passbands, normalizing those measurements for the effects of source and path using the Magnitude and Distance Amplitude Correction (MDAC) methodology, and calculating Pg/Lg ratios for each event. We find that the MDAC-corrected SPE shots fall in the middle of the nuclear explosion population with very little variation due to the differing shot conditions. Thus for particular discriminants at several regional stations, the SPE shots and mining explosions are good surrogates for nuclear explosions, and the differences in depth of burial and single versus multiple shot have only a s...

Regional Seismic Signals from Chemical Explosions, Nuclear Explosions and Earthquakes: Results from the Arizona Source Phenomenology Experiment

“…The dedicated shots have a similar behavior and have been shown to approximately match Mueller and Murphy (1971) explosion spectra (e.g. Bonner et al, 2005). In contrast, the production shots have much stepper falloff with frequency.…”

“…A list of the shots sizes, depths, yields and scaled yields are given in Table 1 and 2. More detail about the geology of each mine and the layout and execution of the dedicated shots can be found in the earlier chapters of this report and in Bonner et al (2005). (Bonner et al, 2005).…”

“…More detail about the geology of each mine and the layout and execution of the dedicated shots can be found in the earlier chapters of this report and in Bonner et al (2005). (Bonner et al, 2005). Yield is weight of ANFO rounded to nearest tenth of a ton.…”

Final Technical Report, 30 SEPTEMBER 2002 - 31 JANUARY 2006; ENERGY PARTIONING FOR SEISMIC EVENTS IN FENNOSCANDIA AND NW RUSSIA

“…The so-called Arizona source phenomenology experiment (Bonner et al, 2005) showed that the designed test shots and mining explosions are good surrogates for nuclear explosions as the magnitude-and distance-corrected Pg/Lg amplitude ratios fall in the range of those for nuclear explosions at NTS. Differences in depth of burial and single versus multiple shots have only a small effect on the amplitude ratios.…”