A strong quake has struck off the southern coast of Alaska, near the Aleutian Islands.
It measured magnitude 7.5 and was 41km deep, according to USGS. It struck at 9:54am (NZ time), 94km southeast of Sand Point.
A tsunami warning has been issued for the islands, where about 8000 people live, and coastal areas of Alaska, the United States' most northern state.
The Pacific Tsunami Warning Centre said there was no risk to faraway Pacific islands such as Guam.
The quake was initially reported as magnitude 7.4, but revised upwards to 7.5 as more data became available.
It has been followed by aftershocks measuring as strong as 5.8.