Measurement of Velocity Dispersion (bvas)

The program, bvas, measures phase velocity as a function of frequency for a given subsurface interval. The user specifies an interval in the subsurface by the top and bottom elevation. The data are filtered by very narrow band-pass filters. At each frequency, the data are shifted by a sequence of trial velocities (from Vmin to Vmax). For each trial alignment, a semblance value (Sheriff (20) ) is calculated which measures the degree to which the data were aligned. The larger the semblance, the better the alignment. A Golden Section search solves for the best alignment velocity in the bracketed interval. The solution is written to a file, bvas.his, which is later read by the Octave procedure, cainv3.m.



Subsections