After facing lava and toxic gas from the Kilauea volcano eruption on Tuesday, Hawaii residents are being warned the worst is yet to come.

Hours after residents heard warning sirens and received phone messages urging them to “evacuate now”, US Geological Survey on Thursday (AEST) raised the potential for “explosive eruptions” in the coming weeks.

“If the lava column drops to the level of groundwater beneath Kilauea Caldera, influx of water into the conduit could cause steam-driven explosions,” it said.

“Debris expelled during such explosions could impact the area surrounding Halema‘uma‘u and the Kilauea summit.”

Along with steam-driven explosions, Hawaii residents are being warned of hazardous volcanic smog and acid rain.

Residents of Lanipuna Gardens in the southeast of Hawaii’s Big Island were told to head for the coast as they were in immediate danger from clouds of sulfur dioxide gas and fountains of lava.

The USGS could not say with certainty that explosive activity will occur, saying if winds weaken that gas and other volcanic pollutants can settle easily with moisture and dust to create a haze called volcanic smog.

However, high chances of rain in the coming days would also cause sulfuric acid droplets to fall, reports state.

“EVACUATION NOTICE: New Vents Open, Lanipuna In Danger,” Hawaii County Mayor Harry Kim tweeted.

EVACUATION NOTICE: New Vents Open, Lanipuna In Danger https://t.co/UaNrz9w312

— Mayor Harry Kim (@MayorHarryKim) May 9, 2018

Volcanic vents and lava flows have destroyed 36 structures since Kilauea erupted last Thursday and all 1700 residents of Leilani Estates residential area, of which Lanipuna Gardens is a part, have been told to get out of their homes in the semi-rural area.

The Kilauea eruption last week created new volcanic vents on the ground miles east of the summit, releasing slow-moving lava and toxic gas into island communities.

Emergency teams donned breathing equipment and protective clothing to evacuate residents who stayed behind to care for pets and livestock. Crews drove gingerly over highways as steam shot from widening cracks in the asphalt, local TV footage showed.

Mayor Kim pleaded with residents to leave their houses and not put rescue crews at risk.

Geologists reported loud jetting and booming sounds as lava shot from the new fissures around 19km from the cone of the shallow-sided volcano, the Hawaiian Volcano Observatory reported.

The new eruptions brought to 14 the number of vents that have opened since Kilauea started spraying fountains of lava as high as 90m into the air. 

Lava has been bubbling out of about 4 km of fissures that officials have warned are slowly spreading eastward.

On Friday, the southeast corner of the island was rocked by a powerful magnitude 6.9 earthquake on the volcano’s south flank, the strongest since 1975. Smaller quakes followed, and the eruptions and tremors could continue for months.

-with AAP