A powerful earthquake measuring 6.1 on the Richter scale rocked southern Alaska on Saturday, according to the United States Geological Survey (USGS) website.

The earthquake occurred at 18:09:50 GMT on Saturday, with its epicenter some 259 kilometers southwest of Anchorage, Alaska's largest city, and with a depth of 94.5 kilometers, said a computer- generated message released on the website.

The website message said that the event has not yet been reviewed by a seismologist.

Meanwhile, the Anchorage Daily News quoted the Alaska Earthquake Information Center as saying that the earthquake had a preliminary magnitude of 5.7.

It hit south-central Alaska at 9:09 a.m. local time, and was centered below Cook Inlet some 50 miles (80 kilometers) west of Homer, the Center said.

The shake could be felt in Anchorage but was not expected to cause a tsunami, it added.

The West Coast and Alaksa Tsunami Warning Center confirmed on its website that no tsunami is expected as a result of the quake.

The Anchorage Daily News and other U.S. media said there was no immediate report of casualties or damage.

Historical records show that a massive earthquake of magnitude 9.2 struck Alaska on March 27, 1964, the largest one in North America and the second largest ever recorded in the world. It triggered a tsunami wave that struck the U.S. Pacific coast and killed more than 100 people in Alaska alone.

(Xinhua News Agency January 25, 2009)