A flow was less than a mile away from Highway 137 and would reach it in a matter of hours, officials warned on Saturday.
The volcano has been violently erupting since the beginning of the month, its deadly lava spreading into residential areas– destroying around 40 structures and forcing around2,000 people to evacuate.
But the flow changed dramatically on Friday as one fissure ramped up, destroying four more homes and isolating residents, some of whom had to be airlifted to safety.
The change is attributed to new magma mixing with 1955-era magma in the ground, creating hotter and more fluid flows, scientists said.
“There’s much more stuff coming out of the ground and it’s going to produce flows that move further away,” said Wendy Stovall, a US Geological Survey volcanologist.
By Saturday morning, two of 22 fissures had merged, creating a wide flow advancing at rates of up to 300 yards (274 metres) per hour.
Aerial footage from the USGS showed fast-moving lava advancing to the southeast. The flow was 1.5 miles (2.4km) from the ocean, scientists said.
Experts are uncertain about when the volcano might calm down.
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“We have no way of knowing whether this is really the beginning or toward the end of this eruption,” said Tom Shea, a volcanologist at the University of Hawaii.
“We’re kind of all right now in this world of uncertainty.”