We didn't feel the Napa quake last year ~60 miles away (well, my son claimed he did after hearing about it, and the cats were a bit agitated), but when I went out later in the morning the metal skimmer cover was half off, and the concrete around was wet. I at first chalked it up to being stupid and forgetting to cover it the previous night, but after another report realized that it must have been from the quake. I wish I had seen it; pretty impressive that there was enough water movement to pop the cover off like that. I guess that's why tsunamis are so powerful; it only takes a tiny shift of the ocean/pool floor to create massive ripples.