The Clinton administration has expressed an interest in a Comprehensive Test Ban Treaty (CTBT), but few people realize that such a treaty may require detecting, locating, and identifying seismic events as small as mD = 2.5 [Wallace et al., 1992]. The lowest magntiude level to which monitoring must be accomplished depends on quantification of evasion scenarios such as decoupling [Murphy et al., 1991].

To monitor a CTBT, small events—including those resulting from human activities such as construction and mining—must be discriminated from nuclear explosions. The number of man-made events greater than 50 tons in the United States is 10,000 per day [Richards et al., 1992] with one shot over 200 tons.