What makes you so sure it happens suddenly and destructively? (All we observed is gradual drifting and I don't know of any historical proof that satisfies my extraordinary evidence for extraordinary claims threshold.) Why the confidence that this is so imminent? (Every other geological event we've studied is extremely difficult to predict with accuracy, like earthquakes where we have many observations under our belt and still no useful forecasting. Even 99% time accuracy is thousands of years window of opportunity.)