A magnitude-7.0 earthquake on Friday struck Alaska's largest city and prompted authorities to issue a tsunami alert for coastal areas of that remote US state, although the warning was subsequently canceled.

The US Geological Survey said the epicenter of the quake was just outside Anchorage, which is home to nearly 300,000 people and the biggest city in the least densely populated US state.

The US National Tsunami Warning Center issued the tsunami alert but announced on Twitter about a half-hour later that it had been canceled.

The powerful temblor, which struck at around 8.30 am local time, damaged buildings in that city and caused widespread damage, based on videos broadcast by US media.

Eyewitness footage seen on US television showed the impact of the quake on small shops, grocery stores and other establishments, where food and beverages and other products were knocked to the ground while light fixtures rocked back and forth.