Passive Source Seismology of the Rocky Mountain Region

Abstract

Two recent passive source (earthquake) seismic experiments have produced a teleseismic and regional event data set which provides constraints on the structure of the crust and upper mantle beneath the Colorado Rocky Mountains and two major Precambrian province boundaries. The passive source component of the Continental Dynamics of the Rocky Mountains (CD-ROM) experiment included two dense north-south linear arrays of broad-band seismometers straddling Precambrian province boundaries in Colorado, Wyoming, and New Mexico. The Rocky Mountain Front (RMF) experiment included thirty broadband seismometers spaced uniformly throughout Colorado. Results from a spectrum of seismological imaging and inversion techniques indicate that the Cheyenne Belt Archean-Proterozoic boundary in southern Wyoming has signatures in both the crust and upper mantle, while the Yavapai-Mazatzal province boundary is less clearly defined. Studies of data from the RMF experiment show pronounced low seismic velocities in the crust and upper mantle beneath the Rocky Mountains, and high attenuation (low Q) in the mantle. Techniques of passive source seismology used with RMF and CD-ROM experiment data are described here, along with reference to corresponding studies.