Earthquake under Maui strongest to hit in years

The earthquake that shook Maui on Sunday night was the most powerful to originate under the island in more than five years, but no damage was reported, according to the Hawaiian Volcano Observatory.

The quake's magnitude was 3.5. The last time an earthquake of similar size originated here was April 4, 2008, when a 3.1-magnitude temblor was located 1.8 miles northwest of Paia.

Sunday's quake was located on the southern flank of Haleakala between Kaupo and Kipahulu.

The last destructive earthquake, a 6.7-magnitude shock on Oct. 15, 2006, originated in Kiholo Bay on the Big Island. It did more than $100 million in damage, including to bridges in East Maui, resulting in the closure of Piilani Highway for years.

The magnitude of earthquakes is measured on a logarithmic scale, so the difference in power between any points 1.0 units apart on the scale is about 31.6.

Therefore, the difference in power between a 3.5 quake and the 6.7 quake is not a factor of two. The larger quake was about 30,000 times as powerful as Sunday's quake.

The U.S. Geological Survey said Monday that it received more than 600 reports after the 8:39 p.m. quake. "Weak shaking" was felt throughout Maui, Molokai and Lanai, as well as in northwest Hawaii and on Oahu.

USGS, which operates the observatory, said Sunday's earthquake is believed to be the result of flexure of the Earth's lithosphere (stiff crust) to accommodate the weight of Haleakala volcano. Similar adjustments produced the Kiholo Bay and another earthquake in 2006.

The earthquake most likely was not directly associated with magma or eruptive processes.

For eruption updates and other information, visit the Hawaiian Volcano Observatory Web site at hvo.wr.usgs.gov.