Take the mass of a few cubic miles of rock, let it fall (slide down an underwater slope) a mile-ish, and there's an ample supply of 0.5mv^2. And, whether above

Take the mass of a few cubic miles of rock, let it fall (slide down an underwater slope) a mile-ish, and there's an ample supply of 0.5mv^2. And, whether above or below water, really huge avalanches have dynamics that seem quite counterintuitive. (Due to the square/cube law and other effects.)