I was standing on top of Castle Rock this evening when it began to jiggle, kinda like jello on a saucer. The tree and rock vibrated for about 10 seconds, and I heard a low hum through Tumwater Canyon.
I just checked the Pacific Northwest Seismic Network and sure enough, they registered a 4.3 quake near Lake Wenatchee
Wild and weird sensation to feel it moving under my feet.