to alter blasting and mining engineering approaches. The DOE Working Group acknowledged the value of monitoring approaches, but placed greater emphasis on decreasing the visibility of seismic signals.
A majority of mining-induced seismic signals, including those resulting from all blasting at most mines, would be invisible to the CTBT monitoring network because of their small size. Among those signals that are visible to the IMS, most could be clearly associated with legitimate mining activities by a voluntary characterization program, thus substantially reducing any ambiguity. Mining operations that use large explosive yields—that is, greater than the 300 metric tons TNT-equivalent specified in the treaty—could voluntarily submit the time and locations of a few of their larger blasts to the agency (not yet specified) responsible for U.S. CTBT compliance. The resulting data could lead to improved travel-time models and corrections that would enable very accurate locations for signals originating at or near those “calibrated” mines. This ability would greatly reduce the ambiguity of many small seismic signals detected by the CTBT seismic monitoring system and would make it possible to rapidly obtain confidence-building information from the mine to explain any questionable signals. For the very few mines that might emit large signals that are still ambiguous despite the process described above, mine operators may want to take more active voluntary measures and allow installation of an unintrusive, on-site monitoring system such as that discussed in the DOE Working Group report. The benefit to the mining companies would be the avoidance of possible international CTBT on-site inspections of legitimate mining activities.
Seismic signals originating from rock bursts, coal bumps, or mine collapses are more likely to be ambiguous than those originating from blasting operations. For mining operations that had significant geologic events that might generate observable seismic signals, it would be extremely useful for treaty monitoring if these operations would report the location and approximate time of these events. However, this is not included as one of the voluntary measures within the treaty,
The burden of the above measures to decrease ambiguity of seismic signals should not be onerous to the mining community. The NRC review committee believes that U.S. industry cooperation in this important national initiative will be forthcoming.
Such a voluntary approach to decreasing the ambiguity of seismic signals originating from mining operations within the United States could set a positive example for other countries to participate in confidence-building measures under the treaty regime.