Scientists have warned that Mount Kilauea is threatening to start a series of explosive eruptions.
Two thousand people were forced to evacuate their homes after the volcano started to erupt on May 3.
A new fissure opened up on Saturday around a mile east of the existing vent system that has devastated the island’s Leilani Estates residential area.
Within hours of opening, it had piled reddish-black lava about 40 feet high and at least 150 feet in length.
Chunks of magma were thrown 100 feet into the air.
Scientists have warned that a steam-driven eruption from the summit’s crater could throw ash plumes 20,000 feet high and spread ash up to 12 miles.
The announcement came after Hawaii governor David Ige made the request for funding on Wednesday and estimates that the cost to protect residents could exceed $2.9 million (£2.1 million) in May alone.
The declaration means that assistance will be made available for repairs to facilities such as roads, public parks, schools and water pipes damaged by the volcano. It also covers the cost of hiring people to create roadblocks, geologists and the military.