House shakes violently at least once a day
The Maryland Geological Survey, a division of the Maryland Department of Natural Resources, operates the Maryland Seismic Network in cooperation with several colleges or universities. The tremors you're feeling are unlikely to be natural earthquakes. However, if they're strong enough to be detected by seismology stations, there's a good chance the operators of the network may have already identified the origin of the tremors so that they can remove or ignore that data in their sensor readings. Try calling the Survey or the seismology department at the schools and find out what they know. If they haven't already identified the origin or didn't know about the tremors you might pique their interest or at least get some semi-local tips to assist your sleuthing.