The Solomon Islands were struck by two powerful earthquakes on Sunday, triggering a regional tsunami warning as authorities attempt to determine if there was any serious damage or injuries. 

Government spokesman George Herming said people throughout the Pacific island chain awoke to the first magnitude-7.6 quake at 7:14 a.m. He said that people on Makira and nearby islands southeast of the capital, Honiara, reported seeing three large waves after the quake.

He said there were no immediate reports of damage or injuries.

The U.S. Geological Survey reported the epicentre was 323 kilometres southeast of Honiara, at a depth of 29 kilometres.

The second, a magnitude-7.7 quake, struck at 11:36 p.m. Sunday, with an epicentre 328 kilometres southeast of Honiara, the capital, and a depth of 20 kilometres, according to the U.S. Geological Survey.

Following the first earthquake, the Pacific Tsunami Warning Center cancelled a tsunami warning after issuing an alert for some Pacific islands. A second regional tsunami warning has been issued. 

Paul Whitmore, director of the National Tsunami Warning Center in Alaska, said powerful waves posed no threat to the U.S. West Coast or Canada after the quake.

The Solomon Islands, home to 600,000 people, was already reeling from devastating flash floods that struck Honiara and other areas April 3. The floods have killed 23 people and left 9,000 more homeless.

Herming said up to 30 more people remain missing.

"It has really been a tough time," he said.

Andrew Catford, the Solomon Islands country director for World Vision, said that the aid group's staff in the Kirakira office in Makira province reported that there was no tsunami, but strong currents and heavy waves pounding the reefs. He said the group's staff evacuated to higher ground as a precaution.

"We felt this one strongly in Honiara. It was close to 30 seconds long," he said.

The Solomon Islands lies on the "Ring of Fire" — an arc of earthquake and volcanic activity that stretches around the Pacific Rim.