Rockburst Research Applied to Nuclear Event Discrimination
Abstract
Rockbursts produce seismic signals that are similar to those associated with near surface earthquakes and explosions. Some of the methods developed for source mechanism studies also encompass imaging techniques appropriate for nuclear event verification, and, as a result, have implications for the Comprehensive Test Ban Treaty (CTBT). Past experiments have demonstrated a clear relationship between Barkhausen Noise (BN) and stress in pipeline steel samples. Stress can affect the nature of the pinning sites at domain boundaries which in turn plays a role in the way that domain walls move and cause BN pulses. We have conducted experiments to detect a relationship between BN and stress in magnetite-rich rocks. These experiments were performed by applying uniaxial loading from 4500N to 55000N to cylindrical core samples of magnetite-rich rocks obtained from the Stillwater Complex in Montana. A pick-up coil was used to detect the BN pulses and an electromagnet was used to magnetize the samples. BN pulses were recorded during a specified time interval for each increment of loading. The pick-up coil was positioned to be near magnetite-rich regions of the sample. We have observed a linear increase in the number of BN pulses with increased loading. Ongoing research is focused on refining the experimental procedure to increase the bandwidth of recording and eliminate possible sources of noise in the experiments. The results of this study might help us to understand the nature of the remagnetization that often accompanies large-scale tectonic events. Moreover, this study could lead to a method of nondestructive testing to determine state of stress at mine walls.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 30, 1999
- Accession Number
- ADA376288
Entities
People
- Bill Sill
- Hana Baker
- Holly Hoffman
- Marvin Speece
- Misty Cook