The community of Puna remains on high alert after a set of new eruptions spewed “lava bombs” 100 feet (30 metres) high into the air.
Puna is one of nine districts on the south-eastern side of Big Island, Hawaii’s largest and most southerly island, which is also home to the volatile Kilauea volcano.
Two new fissures opened within the last 24 hours, bringing the total to 19, but fissure 17 remains a particular concern for authorities.
The large land crack has produced a flow of molten rock travelling east-southeast towards the ocean at a speed of about 100 yards an hour.
The coastal dirt road it has overtaken is one of the last exit routes for about 2,000 residents based at the south-east end of Big Island.
Will Kilauea eruptions lead to Big Island evacuation?
Around 2,000 residents from the Lower Puna district of Big Island have been evacuated since the volcanic eruptions started 10 days ago, but scientists have predicted bigger explosions to come.
Hawaii National Guard spokesman Jeff Hickman warned of the need for mass evacuations on the island if lava were to reach major highways.
He said: “There’s a lot of worst-case scenarios and roads getting blocked is one of them.
The military spokesman made the predictions while standing on Highway 137, where lava could hit, some two miles (3 km) away.
The United States Geological Survey has said that new lava outbreaks were likely later this month as the summit lava lake level drops.
A particularly violent eruption has the potential to create a 20,000-foot plume that could spread debris over 12 miles (19km).
Big Island measures 4,028 sq miles so it is not certain that the whole island would need to be evacuated in such an event but evacuations could surge from current numbers.
Hawaiian Volcano Observatory Deputy Scientist-In-Charge Steve Brantley said a similar seismic event in 1955 lasted 88 days so the fall out from eruptions and toxic sulfur dioxide gas has the potential to worsen.
He said: ”It’s optimistic to think that this is the last fissure we’re going to see.”
The Hawaii Fire Department also issued “condition red” alert on Monday after some fissures in the Lanipuna Gardens area rated highly for sulfur dioxide.
The alert said: “Condition RED means immediate danger to health so take action to limit further exposure.
“Severe conditions may exist such as choking and inability to breathe.”
Hawaii County Civil Defense Agency has warned people to be on the look out for potential gas emissions.
A statement warned: “This is a serious situation that affects the entire exposed population.”