Hawaii volcano explosion hurls boulders

HILO, Hawaii, March 20 (UPI) -- A blast caused by natural gas pressure in Kilauea's Halemaumau Crater prompted the closure of parts of Hawaii Volcanoes National Park.

The explosion, which released no lava but hurled boulders across 75 acres, was comparable to a 3.7 earthquake, the Honolulu Star-Bulletin reported.

Hawaiian Volcano Observatory head Jim Kauahikaua said it is possible an area up to 100 feet in width caved in and blocked pressure-release vents, leading to the Wednesday explosion.

A 65- to 100-foot crater was left where the rocks blew apart and surrounding areas were covered in rocks and dust from the blast, Kauahikaua said.

The last time Halemaumau exploded was in 1924 when debris flew up to 2 miles above the crater.