Localization of geophone stations by maximum-likelihood estimation

Abstract

Reliable interpretation of seismic data in ocean bottom surveys or crust and upper mantle investigations requires precise knowledge of the position of the seismic sensors. Special problems arise when operating with free-falling ocean bottom seismometers (OBS). Since the ship's position and its towed signal sources (air gun, uniboom) or explosives are fairly well known based on high-precision navigation systems, one can determine the geophone positions indirectly from their response to the source excitation. Here, a newly developed source parameter estimation code [A. B. Baggeroer, W. A. Kuperman, and H. Schmidt, J. Acoust. Soc. Am. Suppl. 1 79, S56 (1986)] is first used to determine the performance bounds for a localization based on seismic interface waves. Then, an actual shear speed profile is determined by inversion of a new data set obtained using explosive sources, and a maximum-likelihood estimation of the geophone position is performed. By comparing the results with the actual experimental geometry, it is demonstrated that in spite of the fairly long wavelength of the interface waves, a reasonable resolution can be achieved by such a technique.