Quake that struck off Russia's Kamchatka upgraded to magnitude 7.8

(Corrects revised magnitude in second paragraph to 7.4 from 4.4.)

July 17 (Reuters) - An earthquake that struck off Russia's Kamchatka Peninsula on Tuesday was upgraded to a magnitude 7.8, the U.S. Geological Survey said.

The quake, which struck far away from mainland Russia, was initially reported as a magnitude 7.7 before being revised down to 7.4 and finally upgraded to 7.8, a major quake normally capable of causing widespread and heavy damage when striking on or near land. (Reporting by Sandra Maler in Washington; Editing by Toni Reinhold)