the gulf needs a good idea too

I don't understand why they have not sealed off the hole (pipe) which is spewing the oil/gas.  It's 5,000 ft from the water level down to the seabed.  The broken pipe, cap etc is at the seabed floor.  The pipe then goes down another 10-13,000 ft through the seabed to the oil reservoir.  Simply put some explosives 1 or 2 thousand feet down into the seabed around the pipe, and implode it.  This would cause the surrounding seabed to collapse around and fill the hole (at least partially enough to seal it).  Woudn't that work?  What are your ideas?