We examined over the Israel Seismic Network (ISN) the seismogram envelopes
vs. group velocity V = R/T, where R is the epicenter distance and T the tra
vel time, and found out a persistent difference between quarry blasts and e
arthquakes. The data include 53 seismic events occurring in northern Israel
with magnitudes of M-L = 1.0-2.6 and at distances of 15-310 km. Within the
1-4 km/s range we measured the velocity V-ms at which the envelope reaches
its maximum for each ISN station. A simple linear discrimination function
c = b + 0.33a, based on an empirical relationship between the V-ms and R: V
-ms = a + b ln(R) provides effective separation between the regional earthq
uakes and explosions. These results are attributed to different excitation
of regional surface waves from these two types of seismic events. (C) 1999
Elsevier Science B.V. All rights reserved.