Lava has consumed about two dozen homes near the volcano over the last week and about 2,000 people are evacuated from the danger zone.
A river of lava more than a mile long is flowing toward the ocean from one of the fissures.
That doesn't mean the "big one" won't happen, Coombs said.
They said: "Severe conditions may exist such as choking and inability to breathe".
Meanwhile, fissure 17, which opened Sunday morning, remained the most active, said Janet Babb, Hawaiian Volcano Observatory geologist.
Residents are being warned to prepare for an evacuation at any moment.
Almost 20 fissures have opened since the volcano started erupting 12 days ago, and officials warn it may soon blow its top with a massive steam eruption that would shoot boulders and ash miles into the sky.More news: Meghan Markle's mother Doria Ragland will soon arrive in London
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Most of Hawaii's destinations, restaurants and hotels are unaffected by the volcanic activity, with the exception of Hawaii Volcanoes National Park - home to Kilauea - which is closed to visitors, according to USA Today.
No injuries were reported as - now 19 - fissures have reportedly opened up on the Big Island near Leilani Estates.
Unsafe levels of sulfur dioxide were rising from some fissures, Hawaii County officials told CNN.
"It sounded like hammers in the dryer", she said. "When the sulfur dioxide hit my lungs once, it took my breath away".
"We do have five active volcanoes in our state", said Brian Terbush, quake and volcano coordinator at Washington EMD. So far, at least 37 structures have been destroyed, and counting.
In addition to the threat of gas and fissures, there are concerns about what's known as phreatic eruptions. The largest projectile was about six feet in diameter and still sits south of Halema'uma'u along the current Chain of Craters Road as a mute reminder of how an apparently tame summit crater can become violent even with no new lava in evidence. That would cause the "explosive" eruption, along with widespread ash fall, Maddie Stone of the Earther blog explained.
But it will be hard to warn residents who may be in the path of such an eruption.
Civil Defense officials are warning of the possibility of an "explosive eruption" because the lava level continues to drop in the summit lake at Mount Kilauea.