Mauna Loa is erupting, prompting an ashfall advisory for Hawaii’s Big Island

The world’s largest active volcano, Mauna Loa, is erupting for the first time in nearly 40 years, sparking an ashfall advisory Monday for Hawaii’s Big Island and surrounding waters until 10 a.m. HT (3 p.m. ET).

Though lava is flowing down one side of the volcano, the eruption in Hawaii Volcanoes National Park is not threatening communities, the US Geological Survey said midday Monday.

“All indications are that the eruption will remain in the Northeast Rift Zone,” the agency said in an advisory, referring to an area where a volcano is splitting, allowing for lava flow. “Volcanic gas and possibly fine ash and Pele’s Hair (strands of lava glass) may be carried downwind.”

A “trace to less than one quarter inch” of ashfall could accumulate on parts of the island, the National Weather Service in Honolulu said.