Use of correlation analysis to interpret continental margin ECOOE refraction data

Abstract

Numerical time series analysis has been applied in the study of a set of refraction records obtained from a series of explosions detonated on the continental margin east of the Maryland coast. Correlation filters made it possible not only to find arrivals that were buried in the noise but also to distinguish between arrivals that were nearly coincident in time. Since this technique enabled us to obtain more arrivals on the seismic record than could be found visually, the travel-time curve is more complete for the machine picks than for the visual picks. Velocity-depth calculations were made and compared, using the intercept times and the velocities obtained from both travel-time curves (visually picked and machine-picked data). It was calculated that the Moho dips toward the continent at about 4° and has a depth in the Maryland area of nearly 25 km. It was also found that the definition of the Mono has considerable north-south dependence, both in energy and in frequency content of its refraction arrival. The crustal layer overlying the Moho was found to dip west both on the continental shelf area and under Maryland, whereas the shallowest observed refractor was found to change direction of dip from west on the shelf to east under the coast. Both these layers strike approximately north-south in each region.