>> reporter: in the last week, rattled plainfield, connecticutnts residents had made more than 300 calls to 911. >> reporter: marian diggs says she's felt every earthquake. >> i was sitting in bed drinking my early-morning cup of coffee before everybody got up-- my time-- and all of a sudden i heard this loud boom. >> reporter: people here have reported minor damage from the 12 earthquakes that have hit between the towns of danielson and plainfield. most had been under two magnitude. the largest occurred monday morning at 3.1. seismologists at boston college western observatory are collecting data hoping to find out why the so-called swarms are happening. >> we've had a few scattered epicenters in the past from that part of the state, but this is some something that's new for us. >> reporter: scientists tell us earthquakes are usually caused