Thing is, this isn't like having an 18 mile wide crater on the surface, which by itself would have been a catastrophe beyond description.
This is an 18 mile wide crater AFTER IT HAD TRAVELLED THROUGH 2 MILES OF OCEAN!!
I remember reading something about it raining forty days and forty nights, this sure would do it.
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I remember reading something about it raining forty days and forty nights, this sure would do it."
actually this might be it. the timing would be early enough to fit into other cultures' flood/rain stories (sumeria had one IIRC, and I have read that some indian cultures did as well?), and would certainly put enough water into the atmosphere to drasticly disrupt weather patterns worldwide.