4.1-magnitude quake
rattles Windward Oahu

Temple Valley residents Ken and Joyce Libby were shaken by an earthquake early yesterday but never knew for sure what it was until last night.

"I heard this rumbling, bigger than any kind of truck that drives by, and it's louder than anything we ever hear from the Kaneohe Marine base," Joyce Libby said. "The waterbed shook just as I was about to get up. The walls shook. It's like the whole house was trembling."

The 4.1-magnitude earthquake at 5:52 a.m. off the Windward coast of Oahu is rare, said seismologist Stuart Koyanagi with the U.S. Geological Survey's Hawaii Volcano Observatory.

The quake's epicenter was estimated to be about 19 miles east-northeast from Kaaawa and 4.4 miles deep.

Koyanagi said the observatory received about a dozen reports from Kailua and Kaneohe yesterday morning. If it was deeper, it would usually be felt in a wider area, but the intensities would be lower.

"If it was closer to the city, it would have been felt by probably more people," he said.

Koyanagi cautioned that the numbers are suspect. The magnitude is a "best estimate" and probably falls between an upper 3 and a low 4 magnitude, which is difficult to determine with just four seismic measuring stations on Oahu.

Ken Libby said he strongly suspected the "very low-frequency rumbling sound" and a good shake was an earthquake, but wasn't sure until a reporter confirmed it last night.

He recalled an earthquake in Kailua in the 1970s, which had caused the water from a 130-gallon aquarium to spill out. "We don't have an aquarium anymore," he said.

Joyce Libby noticed the wild peacocks were squawking more than usual.

Was she afraid?

"For a very short moment, yes, because we are extremely close to these mountains right at the foot of this mountain range," she said.

With just a few yards of soil behind their house, Libby believes a large earthquake might cause their house to slide into the gully one day.

Geologist Floyd McCoy with the Windward Community College said the earthquake was moderately deep and that it is shallower earthquakes that should be cause for concern.

"I'm surprised there aren't more," he said. "The Big Island had 10,000 earthquakes last year. The fact that we have so few and we don't feel them surprises me."