The earthquake hit less than 30 kilometers (19 miles) off the island of Makira -- and 70 kilometers (43 miles) southwest of the island's city of Kirakira -- about 4:38 a.m. local time Friday (12:38 p.m. ET Thursday), the US Geological Survey said.
A number of tsunami warnings issued not long after the quake have been canceled, the Pacific Tsunami Warning Center said.
The largest observed wave, according to sea level gauges, was only 0.12 meters (5 inches) near Honiara on the island of Guadalcanal, some 200 kilometers (124 miles) northwest of the epicenter
In an area where temblors are common, "the earthquake was one of the biggest and longest I have ever felt," said Tali Hong, a resident of Honiara, the capital of the Solomon Islands. "I was born here in Honiara and lived here most of my life.
"I'm located in central Honiara, in one of the big urban areas. Just checked with my neighbors and surrounding area; there is not visible damage. However, we have no electricity at the moment."
At the capital's Heritage Park Hotel along the waterfront, awakened guests came out of their rooms to assess what was happening, said Richard Konari, a receptionist there. Things appeared to be returning to normal, he said.
"I have not seen any damage, but the feeling was like nothing I've experienced," Konari said. "It was a more powerful feeling than I've felt in the past."
A guest at the hotel, Sita Leota, told CNN she went to higher ground -- a hill by the Parliament -- after reading about the tsunami alert online.
"Up on (the hotel's) third floor where I was, the whole building swayed -- like riding a wave," said Leota, who was visiting from Samoa.
A receptionist at Honiara's Pacific Casino Hotel said the shaking -- about five minutes long -- made it feel like she was floating on water. She said she isn't aware of any damage to the building.
"We don't experience quakes like this. It's big," she said.
After the major quake, a series of almost a dozen aftershocks, including one measured at magnitude 5.9, continued through the day.
Along the 'Ring of Fire'
Makira, also known as San Cristobal, is one of the southernmost parts of the Solomon Islands, an archipelago located hundreds of kilometers northeast of Australia that is home to more than 500,000 people.
The Solomon Islands are along the "Ring of Fire," a zone of seismic activity and volcanoes around the edges of the Pacific Ocean. It's a vast area where about 90% of the world's earthquakes occur, according to the USGS.
The ring, which actually is shaped more like a horseshoe, includes more than 400 underwater volcanoes and stretches 25,000 miles from New Zealand, past Japan, across the Bering Strait and down to the tip of South America.