Lanny Nakano, acting administrator with Hawai'i County Civil Defense, said there were no reports of injuries or damage. Also, the quake did not generate a tsunami, he said.

But Nakano said his office received many calls from people who felt the ground shake.

"All the ones that called said no damage, but they were just concerned because it was a pretty good jolt," Nakano said.

Debbie Wong Yuen said she was asleep in her Pahala home when she felt a "quick jolt." Then it really got wild.

"It just started coming and got a little strong and then it kind of simmered down," said Wong Yuen, a library assistant at the Pahala Public School and Library. "Then it got a little strong again and kept going and going and you just kind of lay there and think, 'Is it going to stop? Is it going to come harder?' "

Wong Yuen said she's lived in Pahala for 24 years and has been through many earthquakes, including a major temblor in 1983 that damaged her home. But she said yesterday's quake will be remembered as one of the stronger ones.

"When it starts rolling you get kind of concerned, like, 'Is it just going to continue?' and you just get really slammed after that," she said. "Having a big aquarium filled with water, you kind of worry about that spilling over and ruining the carpet."

Steve Brantley, deputy scientist in charge at the Hawaiian Volcano Observatory, said the cause of the earthquake was not known yesterday. But at 25 miles below Earth's surface, Brantley said, it may be related to the magma-generation zone beneath Lo'ihi, a submerged active volcano about 20 miles south of the Big Island.

Brantley said there have been three earthquakes recorded in Hawai'i with a magnitude of 5 or greater since January 2000, and yesterday's quake was the largest in six years. The last magnitude-5 earthquake occurred on Aug. 26, 2003, he said.