Open AccessAftershocks and on-site inspections under a test ban: A progress report
Author(s) -
Albert T. Smith,
Craig A. Schultz,
J.J. Zucca
Publication year - 1995
Language(s) - English
Resource type - Reports
DOI - 10.2172/231958
Subject(s) - aftershock , microseism , seismology , geology , explosive material , nuclear explosion , event (particle physics) , rockfall , seismogram , test site , mining engineering , forensic engineering , engineering , archaeology , geography , landslide , physics , quantum mechanics , nuclear physics
An ambiguous seismic event detected remotely under a comprehensive test ban (CTB) may require an on-site inspection to determine the nature of the event. Provided they are present, aftershocks and microseismic events could play a key role in narrowing the inspection area and focusing the efforts of the inspectors. Of particular interest are the low-frequency, emergent aftershocks that have been observed after underground nuclear explosions at the Nevada Test Site. If these events can be shown to have unique characteristics, their detection could greatly increase the chances for a successful inspection. The authors have been characterizing aftershock swarms from underground explosive events and from other events that may be encountered during an inspection. This report summarizes an analysis of aftershocks following an underground explosion and microseismic events associated with routine operations at the block-caving Henderson Mine in Colorado. They used as their example of a smaller, single-point explosion the Non-Proliferation Experiment (NPE), a one-kiloton, chemical, overburied, single-point explosion whose aftershock sequence is similar to an underground nuclear explosion. They were interested in studying the Henderson mine because the caving operation is an apparent analog to the chimney formation following an nuclear event and could give rise to similar microseismic events. Mine operations at Henderson result in both low-frequency emergent events and high-frequency impulsive events. The emergent events (hundreds per day) are apparently associated with rockfalls into the crater produced by the caving operations and have many similar characteristics to the low-frequency events from the NPE; however, the low-frequency NPE aftershocks are relatively much more impulsive than those of the Henderson Mine. Unlike the NPE or nuclear events, location of Henderson low-frequency events is extremely difficult using arrival-time methods because of their very gradual onset