In this paper, we modeled 0.5--2.0 s period Rayleigh waves (Rg) generated by quarry and construction blasting for the shallow crustal velocity and intrinsic Q structure in southwestern Connecticut and southeastern New York. In spite of the Rg waves traversing through different geological formations, the Rg dispersion observed along individual paths, namely, the Clinton Point-BCT, the Clinton Point-BPT, the North Brandford-BCT, the New Britain Plainville-BCT and the Reeds Gap-BCT paths, are remarkably similar. The dispersion is similar to the Rg dispersion observed in other parts of southern New England. For a representative shallow crustal velocity structure of the region, we therefore inverted the average dispersion curve observed along the Clinton Point-BPT path. The inverted crustal model, with shear velocity varying between 2.85 and 3.65 km/s down to a depth of 3 km, is similar to the crustal models published earlier for the other parts of southern New England. High-frequency Rg waves are found to be highly sensitive to anelasticity within the near-surface crustal layers. The observed Rg waves require Qβ (shear wave quality factor) as low as 15 to produce the best agreement between data and synthetic. A thin till layer affects the Rg waves significantly provided the layer thickness is of the order of Rg wavelength.

Theoretical study shows that the delay times between charges caused by the temporal finiteness of arrays of explosions during a quarry blast are found to have produced a significant effect on the high-frequency Rg waves. We also investigated theoretical seismograms to discriminate between earthquake and quarry explosions. We found that Rg waves are a successful discriminant only for earthquakes at depths greater than 3 km. The shallow earthquakes show strong Rg waves for dip-slip faults but are preceded by high-frequency shear arrival, especially in the range of 50--125 km. Beyond 126 km, pSmS and its multibounces become critical with distance and contribute strongly. These waves appear on the explosion siesmograms as shear waves. So, this shear wave may provide a diagnostic in the range between 50 and 125 km for discriminating earthquake seismograms from the small quarry explosions. ¿ American Geophysical Union 1992