(CNN) -- Scalding, black lava crept out of the largest fissure ripped open by Hawaii's Kilauea Volcano, consuming the lush, green landscape around it and lobbing balls of magma known as "spatter bombs" 500 feet into the air, according to footage and reports from the US Geological Survey.
Fissure No. 17 split the Earth near Leilani Estates, near the eastern point of Hawaii's Big Island, and the USGS published footage of the lava running like a river -- and then a lake -- past three structures in the area.
While authorities reported an 18th fissure opening Sunday, the Hurricane Volcano Observatory walked that back, saying the latest crack in the Earth -- near Halekamahina Loop Road -- was actually part of Fissure 17. On Monday morning, Fissure 18 officially opened, according to the USGS.
No matter what they number them, for residents, the fissures just mean more reasons to run, as the evacuation zones expanded.
Fissure 17 -- the "most voluminous," the USGS says -- is several hundred yards long and was causing serious trouble Sunday, with "lava fountaining, explosion of spatter bombs hundreds of feet into the air, and several advancing lava flow lobes moving generally northeast" from the fissure, the Hawaiian Volcano Observatory said.
"Based on overflight images late this afternoon, additional lava from fissure 17 was also moving slowly southeast. Volcanic gas emissions remain elevated," the HVO said late Sunday.
The observatory added that "future outbreaks" could arise southwest and northeast of the existing fissures.
Nearly 2,000 people have been evacuated since the volcano erupted, sending lava flowing into communities and threatening a nearby geothermal plant.
The volcanic vents, or fissures, have gobbled up dozens of homes and vehicles, with 37 structures so far destroyed.
The Hawaii Civil Defense Agency said in a Sunday message that vacation rentals in Lower Puna were directed to cease operations to relieve the demand for water as well as reduce the area population so emergency responders can focus on residents.
The Hawaii Police Department also enforced the Federal Aviation Administration's temporary flight restriction for Lower Puna. No helicopter or drone activity is allowed without approval.
That vent was about a mile east of the Puna Geothermal Venture plant, where officials removed 60,000 gallons of flammable liquids due to safety concerns.
In addition to the new fissures, USGS officials said an explosive eruption is possible at Halemaumau crater at the top of the Kilauea volcano. Such an eruption could generate ash plumes over an area 12 miles from the summit crater, the HVO said.
Trump signs disaster declaration
President Donald Trump declared a major disaster in Hawaii on Friday. The declaration allows federal assistance to supplement state and local recovery efforts in areas affected by the Kilauea volcanic eruption and earthquake.
Federal funding is available to state, eligible local governments and certain private nonprofit organizations on a cost-sharing basis, the White House said.
The estimated cost to protect residents over the next 30 days is expected to exceed $2.9 million, according to the governor's office.
'They lost everything with the lava'
Aside from evacuations, the Kilauea volcano has had a devastating effect on some residents.
Larry and Geri Butler retired from Seattle to a Leilani Estates home in Hawaii 15 years ago.
The couple was part of the evacuation May 3 and found out May 5, via social media, that their home had been destroyed, their son, Christian Butler, said.
"They are still pretty shook up, but I think the initial shock is starting to wear off," Butler said. "They lost everything with the lava, and have to start over from scratch. I'm not sure that fact has really sunk in with them yet."
Video captured by island resident John Carter and shared on social media shows the Butlers' home engulfed in flames from the vantage point of the front yard. Another video, filmed in the backyard, shows lava consuming the couple's backyard.
Butler said the video was shared by people who live in the area, then his parents found out. His parents called him to tell him the news. Butler lives in the Seattle area.
"I'm not able to be with them during all this," he said. "That makes this all that much more frustrating for me, so I am trying to do all I can for them from here."
He calls the home being destroyed a relief, though, because it helps him focus on his parents' future.
Butler said Sunday that seeing the images of his parents' home is "heartbreaking." He also said his parents, in their 70s, were living on retirement income, so starting over will be a "long, long road." Fortunately, he said, they have insurance.
"They're going to be able to recoup from this," he said.
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