Kilauea, the U.S. state's most active volcano, erupted on Thursday, and lava flows from fissures on its eastern flank have destroyed at least 36 homes and other buildings and caused the evacuation of about 2,000 residents.
The USGS warned that more violent eruptions could shoot "ballistic blocks" weighing up to several tons for 1 km (0.6 mile), spew pebble-sized rocks several miles and cover dozens of miles with ash.
The town of Hilo, population around 43,000, lies 25 miles (40 km) northeast of Kilauea and the village of Pahoa is about 24 miles east.
"The steady lowering of the lava lake in 'Overlook crater' within Halema uma u at the summit of Kilauea volcano has raised the potential for explosive eruptions in the coming weeks," the USGS said in a statement.
Hawaii County authorities reported at 7 a.m. Wednesday (1 p.m. ET/1700 GMT) that growth of the new vents had paused but that they continued to emit hazardous sulphur dioxide. Exposure to very high levels of the gas, which causes acid rain, can be life-threatening, according to the Agency for Toxic Substances and Disease Registry.
Emergency teams donned gas masks and went door-to-door evacuating residents who returned to the Laipuna Gardens neighbourhood east of Kilauea after the initial eruption to care for homes, pets and livestock.
Evacuee David Nail was anxious to learn if his house had been destroyed in the neighbouring Leilani Estates area. He was asleep on the couch in his home when a fissure opened up 2,000 feet (610 meters) away, spewing out lava and gas.
"It sounded like 10 or 20 jet engines," said Nail, 57, who had recently retired to the area from Orange County, California.
He tried to reach his house on Tuesday, but he and neighbours were stopped by a 20-foot (6-meter) tall pile of lava.
"All we could do was sit there and cry," he said.
Fourteen fissures have opened since Kilauea started spraying fountains of lava up to 300 feet (90 meters) from the vents.
About 104 acres (42 hectares) of land have been covered with lava since Thursday.
Kilauea has been in a state of nearly constant eruption since 1983.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
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