A moderate earthquake shook southeastern Alaska early today, but there were no immediate reports of damage or injuries, the Alaska Tsunami Warning Center reported. The 7:01 a.m. temblor measured 5.2 on the Richter scale and was centered on the mainland about 80 miles southeast of Yakutat, or 130 miles northwest of Juneau, said George Carte, a warning center spokesman. In Washington, Don Finley, a spokesman for the U.S. Geological Survey, said earthquake monitors in Golden, Colo., recorded the tremor at a preliminary magnitude of 4.8 on the Richter scale. The Richter scale is a measure of ground motion as recorded on seismographs. Every increase of one number means a tenfold increase in magnitude. Thus, a reading of 7.5 reflects an earthquake 10 time stronger than one of 6.5. An earthquake of magnitude 5 can cause considerable damage. The 1964 Good Friday earthquake in Alaska measured 8.5 on the Richter scale and was centered in Prince William Sound. It generated large waves that devastated several coastal communities and killed at least 114 people as far south as Oregon and Hawaii.
