Measurements of High Frequency Seismic Waves
Abstract
Except for its very onset, the P wave of earthquakes and chemical explosions observed at two narrow-aperture arrays on hard rock sites in the Adirondack Mountains have a nearly random polarization. The amount of energy on the vertical, radial and transverse components is about equal over the frequency range 5-30 Hz, for the entire seismogram. The spatial coherence of the seismograms is approximately exp(-cf delta x), where c is in the range 0.4 to 0. 7 km 1/km 1/Hz, f is frequency and delta X is the distance between array elements. The spatial coherence is approximately independent of component, epicentral azimuth and range, and whether P or S wave coda is being considered, at least for propagation distances between 5 and 170 km. These results imply a strongly and three-dimensionally heterogeneous crust, with near-receiver scattering in the uppermost crust controlling the coherence properties of the waves.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 04, 1989
- Accession Number
- ADA219370
Entities
People
- William H. Menke
Organizations
- Lamont–Doherty Earth Observatory