ANCHORAGE, Alaska—A swarm of earthquakes was recorded Tuesday off Alaska’s Aleutian Islands, including the largest with a magnitude of 6.8 followed by aftershocks. There were few reports of the underwater quakes in the North Pacific being felt in nearby communities in a sparsely populated region of Alaska and no reports of damage, officials said. Natalia Ruppert, a seismologist at the Alaska Earthquake Center, said it was a “very unusual, very energetic swarm of earthquakes.” The largest quake, at magnitude 6.8, was preceded just minutes before by a couple of foreshocks. The strong quake occurred about 2:36 a.m., about 40 miles (64 kilometers) southeast of Nikolski, a community of 39 residents on Alaska’s Unmak Island. The community is about 900 miles (1,448 kilometers) southwest of Anchorage, the state’s largest city. About an hour later, a magnitude 6.6 aftershock was reported in the same area, followed throughout the morning by about a …