An earthquake magnitude 7.7 has been recorded in the Pacific Ocean off Alaska, triggering a tsunami warning.

The quake hit about 60 miles (100 km) southwest of Port Alexander and at a depth of about six miles (10km) according to the US Geological Survey.

A small but possibly destructive tsunami has been generated and a tsunami warning is in effect for parts of southern Alaska and coastal Canada.

A tsunami with a “significant widespread inundation of land is expected” with the first wave expected around 2:15 am PST in Craig, and 2:50 in Cordova, further to the north and widespread dangerous coastal flooding is possible.

The Alaska Tsunami Warning Center says the warning area includes coastal areas from about 75 miles  (120 km) southeast of Cordova, Alaska, to the north tip of Vancouver Island.

“Sea level readings indicate a tsunami was generated,” the US center said in a statement. “It may have been destructive along coasts near the earthquake epicenter.”

Gerard Fryer, a geophysicist from the Pacific Warning Centre said: “We have seen a small tsunami at Port Alexander 100 miles south of the epicentre.

“The tsunami amplitude was 13cm which suggests there may be troublesome waves in the immediate area of the quake, but beyond that there is no hazard so we do not have a tsunami warning for anywhere else in the pacific”.

Homes were shaken in Alaska’s state capital of Juneau some 205 miles (330 kilometers) away, The Juneau Empire newspaper reported. But there was apparently no major damage to the city, the largest in the area.

Juneau resident Archie Hinman told the Empire the quake “shook my Juneau home violently enough to awaken the entire family. No apparent damage.”

The earthquake reading was based on the open-ended Moment Magnitude scale used by US seismologists, which measures the area of the fault that ruptured and the total energy released.

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