Officials in Lafourche and Terrebonne parishes are looking into residents' reports of earth tremors in the area this week. So far, they have no answers. A Lockport resident described feeling a sudden vibration that hit his house at 2 p.m. Wednesday. Chris Boudreaux, Lafourche's director of Emergency Operations, said efforts to find a possible source - such as sonic booms from airplanes or vibrations from oilfield activity - have turned up nothing. Boudreaux said the U.S. Geological Survey reported no seismic activity, although it has few monitors in the area. Paul Caruso, a geophysicist with the Geological Survey's National Earthquake Center, said there are not many seismic monitors in south Louisiana because there is rarely any such activity in the area.