chances are that the pool is in need of major repair now.
thats a bit more than two tons of gravel dumped in there.
to fill that pool you have somewhere around 250 yards of gravel
the weight of a yard of gravel is almost 3000 lbs by itself so you have somewhere around 750,000 lbs of pea gravel in that pool (assuming that the 9 ft deep is constant.)
now when you take the weight of what the pool should have in it
and that pool would be about 50483 gallons at 8.3lbs per gallon or 419096lbs of water, you can see that the pool is holding a bit more weight that designed for. with just the gravel alone.
now, if they did not break out the bottom of the pool for drainage when it rained, then we also have the added weight of water that builds up at the bottom.
considering also that water flows down and out when its in a container, the corners at the bottom are where the most pressure is created when the pool is filled with water. The stone on the other hand is putting the direct pressure on the bottom surface of the pool, and it will most likely not hold that weight very well.
so, even if you empty the pool of all the gravel, be ready to have the pool repaired and a liner installed before you can actually fill it with water and use it again.