…into the ocean? Amounts far beyond the current spill?
Any indication this has happened in pre-history?
I had thought that question about a week ago. Yes it can. It leaks to the surface around the world already and an earthquake could release it in a new spot.
The LaBrea tar pits are an example of oil naturally leaking the surface. Obviously, they’re not quite as serious as what you’re thinking of. Other areas in California had tar or oil visible on the surface when people started looking for oil.
The problem with expecting an earthquake to release large amounts of oil is that the oil has been down there for a LONG time. Even the “the big one” has happened many thousands of times since the oil was laid down. If an earthquake could release a flood of oil, it would have before humans were on the scene. Anything that hasn’t been released in the past isn’t likely to be bothered by the next earthquake.
I don’t know of any prehistoric oil releases that would compare to what’s going on in the Gulf right now, but maybe someone does.
One of the things about looking for oil is that you look for structures where oil is trapped. The disappointment for geologists is finding where there probably once was oil - or the conditions were good for oil, but there is no impervious cap holding the oil in. So, as above - oil that is somewhere that is subject to leaking way after some event will almost certainly have long since done so. Oil that still exists is in structures that have survived geological activity for a very long time. I would guess that tectonic processes will eventually move even stable structures into zones where they may be subject to major disruption. But this is a very slow thing.
Looking for traces of leaking oil is one of the non-traditional (i.e. not seismic) techniques that is actively used to try to find oil. Even flying a sensor over unexplored areas may be enough to identify traces of volatiles from a seep.