The seismic reflection method has been extensively developed by the oil industry for locating hydrocarbon reservoirs in the subsurface, evolving from noisy, sparse single-channel reflection records in the 1920s to the high quality 3-D images that are employed today. Two notable landmarks were the change to multichannel recording in the late 1950s, which allowed each subsurface reflection point to be sampled multiple times producing significant attenuation of both random noise and coherent interfering arrivals, and the change from 2-D to 3-D surveys in the late 1970s. As more reflection data has been recorded, so the computer-based processing has become more sophisticated; for example, backward propagating the recorded data through regions of heterogeneous velocity to create well-resolved subsurface images.
In the 1970s, a group of researchers at Cornell University founded the COCORP group with the objective of using oil industry-style reflection methods to look deeper into the Earth, beneath the sedimentary basins that were the focus of hydrocarbon exploration, The fact that COCORP were able to record reflections from depths of 30-40 km and map them laterally over 10s of km was a revelation, and led to similar research groups evolving in other countries in the late 1970s and 1980s. One such group was the Canadian LITHOPROBE program, which, after a number of test experiments, acquired its first full survey in 1984 across Vancouver Island using the Vibroseis reflection profiling method (LINK TO LP SITE) that had been pioneered by COCORP. This survey identified numerous reflectors within the crust, and above the subducting Juan de Fuca plate, that are still the subject of investigation today, and its success grew into the many geophysical and geological transects that were acquired and interpreted over the next 20 years.