Explosive steam could erupt at the summit of a volcano on Hawaii, hurling rocks and ash miles into the sky, say geologists.

The warning came as steam and lava were reported from an 18th fissure caused by Kilauea volcano on Hawaii’s Big Island, with evacuations ordered.

The East Rift Zone, along which the Leilani Estates neighbourhood sits, from the Kilauea eruption (Cindy Ellen Russell/Honolulu Star-Advertiser via AP)
The East Rift Zone affected by the Kilauea fissures (Cindy Ellen Russell/Honolulu Star-Advertiser via AP)

The Hawaii County Civil Defence issued an alert on Sunday that steam and lava spatter were coming from the latest fissure, to the west of Highway 132 along Hale Kamahina Loop Road, and ordered residents on that road to evacuate.

The 18th fissure opening came after two others opened on Saturday.

Plant workers last week removed 50,000 gallons of pentane stored at the Puna Geothermal Venture plant site as a precaution.