Dangerous levels of the toxic gas are rising from some fissures, Hawaii County officials warned Monday.
“Severe conditions may exist such as choking and inability to breathe,” the county’s civil defense agency said. “This is a serious situation that affects the entire exposed population.”
The agency warned residents to leave the area and to get medical attention if they were severely affected by the gas.
Since the Kilauea volcano erupted May 3, it’s been one nightmare after another for residents of southeast Big Island.
Fissures and threat of more eruptions
Fissure 17, which cracked open on the earth’s surface Sunday morning, remained the most active, said Janet Babb, a geologist with the Hawaiian Volcano Observatoryt. It was fountaining lava and “sending spatter more than 100 feet into the air,” according to the Hawaiian Volcano Observatory’s Monday update.
The general public is being warned to avoid the area of fissures, said Alvin C. Bronstein, Hawaii State Department of Health’s EMS chief, because the gases emitted require cartridge respirators.
The volcanic vents, or fissures, have gobbled up dozens of homes and vehicles, with 37 structures so far destroyed.
In addition to the threat of gas and fissures, there are concerns about what’s known as phreatic eruptions.
These are steam-driven explosions that occur when water beneath the ground or on the surface is heated by magma, lava, hot rocks, or new volcanic deposits, according to USGS. The intense heat may cause water to boil and result in eruptions.
USGS officials have been saying such an explosive eruption is possible at Halemaumau crater at the top of the Kilauea volcano. And it could generate ash plumes over an area 12 miles from the summit crater, the HVO said.
Since May 2, the lava lake in the crater began to drop, which increases the chances for a phreatic explosion.
Babb said those explosions are “notoriously hard to forecast and can occur with little or no warning.”
Most of Hawaii Volcanoes National Park has remained closed since Friday due to several threats, including a possible steam explosion at Kilauea.
CNN’s Amir Vera, Joe Sutton, Chris Boyette and Emanuella Grinberg contributed to this report.