Seismic Surveying from Inland Waterways

Abstract

WE have discussed¹ the use of a facsimile recorder and repeatable source on a shallow inland waterway to obtain continuous seismic reflexion profiles of the geological strata underlying the canal. The reflecting horizons were noted on six separate profiles over a 2 mile section of canal but we subsequently found that it is not possible to identify sub-bottom reflexions unambiguously from a single profile. We have therefore adapted to the canal the method used at sea by Houtz et al.²to record wide angle reflexions and head waves from sub-bottom strata. In this method a “sonobuoy” containing a hydrophone, seismic amplifiers and radio transmitter was left drifting freely while the ship moved away at a steady speed. The seismic profiling source (sparker, air gun and so on) was triggered by a facsimile recorder and the seismic signals received by the hydrophone were transmitted to the ship and displayed on the same recorder.