Well, I believe it's been fairly rainy/snowy there since the quake. I suspect she was oriented so that she was basically getting rainwater or meltwater directly somehow in the rubble.
That rainwater must have been flowing directly to where she was situated. If she had enough food to last more than two months, I'm guessing she had to be fairly mobile underneath all that rubble in order to gather it. It would certainly need to be more than what one could reach from a stationary position.
As others have said, what a miracle...
~ Blue Jays ~