USGS’s home page for the magnitude 3.6 this morning, event ID us2010yua6. No shaking felt in Reston: but rather a boom loud enough to rouse me from indifferent sleep. I checked the basement for some mishap, found nothing. I figured that, somewhere down my row of neighbors, a bookcase had fallen over. Then Leta’s Facebook news feed began to light up with WTF?s from friends in suburban Maryland.