A small earthquake struck just off the coast of Maine Monday, causing slight tremors but no damage, the US Geological Survey said. The agency said the 2.4-magnitude earthquake was centered 4 miles southeast of Boothbay Harbor. Police departments in Boothbay Harbor and Bath said they began receiving calls after the quake struck at 1:19 p.m., but there were no reports of damage or injury. The geological agency received reports of the quake from as far away as Plymouth, N.H., 171 miles from the epicenter.Todd Feathers can be reached at email@example.com. Follow him on Twitter at @ToddFeathers.