Residents on the Big Island of Hawaii have been alerted to rising levels of toxic gas from volcanic fissures.
Geologists are warning that new areas east of the Kilauea volcano may be at risk of molten rock bursting from the ground.
The latest upheaval at Kilauea began last week after the crater floor of a long-active side vent collapsed, triggering a plunge in the molten lake inside the larger crater at the volcano's summit.
The authorities in Hawaii County have sent a text message to residents of the southeast corner of the island, warning tham of a wind change that would bring rising levels of sulphur dioxide gas.
It can be fatal if inhaled in large quantities.
Hawaii's governor has warned that mass evacuations may be required as more fissures open in the ground on the east flank of Kilauea.
Experts say that no new fissures have opened during the last 24 hours. However, cracks in the ground are releasing steam.
What they are saying
"It's just horrible. You can't breathe in there," - evacuated resident Robynn Stagg drove through the thick orange haze earlier this week to check on her home.
"Because the lava intrusion is still active and earthquakes are still occurring, we still think there's a decent chance of new eruptive activitiy at the surface," USGS expert Steven Brantley.