HONOLULU, Feb. 25 (UPI) -- A small earthquake in Hawaii may have been caused by fault lines or by the weight of the islands bearing down on the Earth's crust, seismologists say.
The U.S. Geological Survey said the 3.6-magnitude quake hit at 2:12 p.m. Thursday in the Kaiwi Channel between Oahu and Molokai, the Honolulu Star-Advertiser reported.
While the quake was too small to cause a tsunami, it shook residents around Oahu, the USGS said.
There were no reports of damage or injuries.
Earthquakes occur about once a year in the channel and are not something to be concerned about, Kanoa Koyanagi, a Pacific Tsunami Warning Center geophysicist, said.
"People shouldn't get shook up," he said. "We don't expect a magnitude 6 to occur here."
The fault lines around Oahu are not long enough to produce dangerous quakes, he said.
Another possible source of the quake is the shifting islands, a geologist said.
Floyd McCoy, a professor of geology and oceanography at Windward Community College, said as the weight of the big island of Hawaii pushes down on the Earth's crust, the mantle beneath pushes up elsewhere, slightly lifting Molokai and Maui.
Meanwhile, Oahu appears to be subsiding, he said.
"My guess is it's the differential movement in this upward movement between Molokai and Oahu," he said.
"They're responding to the Big Island. ... That huge mass is pushing down on the Earth's crust, and the response again is a seesaw.
"It's just another wonderful signal that the Earth is alive."
