Residents of the Big Island were warned to take shelter from the ash as toxic gas levels spiked in a small area in the southeast.
Hawaii's Kilauea volcano spewed ash nearly nine kilometres into the sky on Thursday and scientists warned this could be the first in a string of more
violent explosive eruptions with the next possibly occurring within hours.
A spike in toxic sulfur dioxide gas levels closed schools around the town of Pahoa, 25 miles (40 km) east of the volcano, where lava from giant cracks has destroyed 37 homes and other structures and forced about 2,000 residents to evacuate.
"This has relieved pressure temporarily," U.S. Geological Survey geologist Michelle Coombs told a news conference in Hilo.
"We may have additional larger, powerful events." The wind could carry Kilauea's ash plume as far as Hilo, the Big Island's largest city and a major tourism center, the County
of Hawaii Civil Defense warned in an alert.
"Protect yourself from ash fallout," it said.
Some Big Island residents had feared "the big one" after Kilauea shot anvil-sized "ballistic blocks" into the visitors' car park on Wednesday and was rocked by earthquakes that damaged buildings and cracked roads in the park that was closed last week.
But geologists said the explosion was not particularly large and on a par with the last series of steam-driven blasts, which took place in 1924.