Seismology and oil exploration

[Shane Kennedy]

Having just read Scientific America's article on the Cascade fault, I wonder if Seismology/Earthquake monitoring sensors could be used to detect fossil fuel reserves and eliminate the use of air-gun blasting that is wreaking havoc on ocean life. Can the oil companies not use naturally occurring acoustic sources ? Why is it that air-guns are permitted, but using actual explosives (as in salvaging materials from shipwrecks) is tightly controlled and contained within bubble shields ?

 

[davenn]

Greetings Shane

I wonder if Seismology/Earthquake monitoring sensors could be used to detect fossil fuel reserves and eliminate the use of air-gun blasting that is wreaking havoc on ocean life. Can the oil companies not use naturally occurring acoustic sources ?

Not enough events often enough, nor close enough together, nor close enough to the exploration areas of interest
As a result there is a total lack of resolution in determining what lies below. Plus timing would be a huge problem.
Timing of the boomer and the return signal are very precisely known. This allows for pretty accurate determination
of water depth and depth to the various strata and their individual thicknesses.

Why is it that air-guns are permitted,

They may do a little damage to fish life ……. I would suspect that most fish would flee the area after the first couple of booms

When I did geology at university, I did sessions of offshore (and onshore) seismic surveying
There was never a trail of dead fish floating to the surface behind the boat ……Dave

 

[johnbbahm]

I have to agree with Dave, I took several research projects offshore on working seismic ships,
and there were not any trails of dead fish behind the ships.
If there had been there would also be a trail of sea gulls, like what follow a shrimp boat.
Air Guns are much better seismic sources than the aqua pulse that came before them.
An interesting note, the real signal from an air gun is the the bubble release, but the collapse
of the bubble, it produces a very clean negative pulse.