UPDATE 3-Major quakes strike in Pacific off Alaska

(tsunami warning canceled; no damage, injuries reported; previous WASHINGTON)

ANCHORAGE, Alaska, June 23 (Reuters) - A major earthquake of 7.4 magnitude struck in the Pacific Ocean more than 1,000 miles (1,600 km) west of Anchorage on Thursday, prompting a brief tsunami warning for part of the remote Aleutian Islands chain.

No damage or injuries were reported. The warning, which extended for roughly 800 miles (1,300 km) -- from Unimak Pass, northeast of Dutch Harbor, westward to Amchitka Pass, west of Adak Island -- was canceled after a little more than an hour.

A tsunami wave measuring just 6 centimeters tall was recorded at Nikolski, a tiny Aleut village on the island of Umnak, and a 10-centimeter wave was observed at Adak, said Becki Legatt, a spokeswoman for the West Coast and Alaska Tsunami Warning Center in Palmer, Alaska.

The coast of the entire Alaska peninsula and all of the Alaska mainland were never considered to be threatened.

The quake struck shortly after 7 p.m. local time (0300 GMT) at a depth of about 25 miles (40 km). A second tremor of magnitude 7.2 hit in the same vicinity of the Aleutians a half-minute later, the U.S. Geological Survey said.

Quakes of 7 to 8 magnitudes and higher are relatively common in the Aleutians but are generally of little consequence because the island chain is so remote and sparsely populated.

"This is a very seismically active area," said Randy Baldwin, a USGS geophysicist with the National Earthquake Information Center in Golden, Colorado.

A tsunami warning means all coastal residents in the warning area who are near the beach or in low-lying regions should move immediately to higher ground and away from harbors and inlets, including those sheltered directly from the sea. (Reporting by Yereth Rosen in Anchorage; Writing by Steve Gorman; Editing by Philip Barbara)