oil sands = tar sands
seismic surveys = sonic cannons
You have been warned.
For drama and fund raising, the enviros dub them "sonic cannons".
A new promising technique, "marine vibroseis" is showing promise, in shallower waters initially. Land vibroseis has long been successfully used. It is highly directional and limited to a low, specific frequency. IOW, it emits much less 'noise' that can harm sea mammals. The current very expensive workaround is a set of solutions that essentially avoids sea mammals.
For a sense of proportion, a seismic survey of an area might cost $5 million and a well $50 million. But you don't know what you've got until you do a survey. As in the Carolinas, for general economic development reasons, seismic surveys are often a government backed, sponsored or even funded activity. Anything to please the enviros on seismics is money well spent.