The gas "can seep into subsurface voids and explode when heated" or "emerge from cracks in the ground several feet away".
"It's very dramatic. It's very eerie", Jim Kauahikaua, a USGS scientist, told the Associated Press.
He said it was only the second time he's ever seen blue flames during an eruption. Now blue has joined the mix: the blue flames of burning methane gas.
Lava entered the ocean from a third flow, marking the third week of a Hawaii volcano eruption that has opened up almost two dozen vents in rural communities, destroyed dozens of buildings and shot miles-high plumes of ash into the sky.
At the Friend family's home, huge cracks have opened in the ground, stretching across a road and up to and beneath the one-story house.
The sheer force of the lava bomb was what Darryl Clinton remembered feeling first, more powerful than any waves he had ever encountered in the ocean surrounding Hawaii.
The U.S. Geological Survey said sulfur dioxide emissions from the volcano have more than doubled since the current eruption began.
Hawaii's Kilauea Volcano Threatens Crucial Israeli-Owned Power Plant
Hawaii officials have said they may need to carry out a mass evacuation if lava crosses key highways and isolates communities in the mostly rural part of the island where the Kilauea volcano is erupting.
But on Wednesday evening, the agency announced that the situation at the energy plant "remains stable, lava has not encroached further onto PGV property".
Lava reached the Pacific Ocean earlier this week and a new lava flow is expected to enter the ocean east of MacKenzie State Park on Thursday, according to the Hawaiian Volcano Observatory.
At least 22 lava fissures have opened in lower Puna, Hawaii, since a May 4 quake near the Kilauea volcano. The volcano has been in almost continuous eruption since 1983.
Officials have been warning of "laze", a toxic plume created as lava makes contact with water. Explosive bursts of lava, steam and ash are the new normal on the Big Island, and rivers of lava continue to threaten homes - as well as a geothermal electrical plant.
"It's probably going to do this for a little while longer", said US Geological Survey scientist Wendy Stovall on the conference call, describing the stage of the eruption as the "middle" or "kind of the steady state".
One person has suffered a serious leg injury from flying lava spatter.
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