The summit of Hawaii's Kilauea volcano erupted on Wednesday and fissures on its eastern slope sent fountains of lava up to 160 feet (50 metres) high, as the volcano showed no signs of calming down after six weeks of intensified activity.
A steam explosion at the summit will likely shower communities near the volcano with ash, the Hawaii Civil Defense Agency said.
The US Geological Service said: "The summit explosion produced an earthquake with amagnitude of 5.4."
The volcano has produced hundreds of moderate earthquakes since it first began erupting on 3 May caused by magma draining from inside the volcano and moving underground.
The magma has been spouting out of fissures from the ground along Kilauea flank, causing mass evacuations from communities.
The most active fissure now, called "Fissure 8," continued to pour into the ocean at Kapoho Bay, producing a hydrochloric acidmist called "laze," formed when lava enters seawater.
"Gas emissions from the fissure eruption and at the ocean entry continue to be very high," the Civil Defense Agency said.
The Kilauea eruption, now in its 41st day, has destroyed more than 600 homes, spread lava over 2,000 acres of land and opened up at least 22 fissures in the ground, according to Hawaii County Mayor Harry Kim.
It is the most destructive in the United States since the 1980 eruption of Mount St Helens in Washington, which killed at least 57 people.
Hawaii's eruption, however, has produced slow-moving lava that has destroyed hundreds of structures but allowed people to evacuate, in sharp contrast to Guatemala's Fuego volcano that ejected fast pyroclastic flows, which buried villages in burning ash and killed at least 109 last week.