The magnitude of the earthquake that struck off the Alaska Peninsula and produced a tsunami with small waves was revised up to 7.6, officials said Tuesday.
The quake Monday was first reported as magnitude-7.4 and was revised to a 7.5 before the latest revision. There was no major damage from the quake or tsunami.
Don Blakeman, a geophysicist with the National Earthquake Information Center, said magnitudes are calculated using various mathematical formulas. He said revisions can occur as agencies contribute information or add more analysis.
Different agencies also can report varying distances from the quake to nearby communities because earthquakes occur over a wide geographic area, said Michael West, director of the Alaska Earthquake Center.
The quake struck in the Pacific Ocean, centered about 67 miles (118 kilometers) southeast of Sand Point, according to the Alaska Earthquake Center.
Sand Point is about 800 miles (1,288 km) southwest of Anchorage. The earthquake was felt widely in communities along the southern coast, including Sand Point, Chignik, Unalaska and the Kenai Peninsula, according to the center.
The quake produced a tsunami, and a warning was issued for about a thousand-mile stretch of the southern Alaska coast. The warning downgraded to an advisory just over two hours after the earthquake struck, and the advisory was lifted late Monday. Waves topped 2 feet (1 meter) in some areas, according to the National Tsunami Warning Center.