Halemaumau is the crater within Kilauea's summit caldera.
The activity was beginning to show similarities to another event in the area in 1955 that lasted for 88 days, when far fewer people lived near the volcano, Ms Babb said.
A phone alert from the County of Hawaii Civil Defense warned: 'The resulting ash plume will cover the surrounding area.
Hawaii's Kilauea volcano has erupted from its summit, shooting a dusty plume of ash about 30,000 feet into the sky.
Hawaiian officials are now warning those on the Big Island in the path of the ash plume to seek shelter as the ash above Kilauea moves southeast with the wind. Kilauea has already been triggering small earthquakes, creating gas-emitting fissures and releasing flows of lava that have destroyed dozens of homes this month.
An ash plume rises in the distance from the Kilauea volcano on Hawaii's Big Island on May 15, 2018 in Hawaii Volcanoes National Park.
An aviation red alert was issued due to risks that ash could be carried into aircraft routes and damage jet engines, USGS said. Ken Boyer, a resident of nearby Volcano Village, said he heard no rumbling and saw nothing out of the ordinary as daylight swept in.
Warnings to pilots are still in place because of the plume that reached 12,000 feet (3,658 meters) Tuesday.
Such eruptions, last seen almost a century ago, have been a looming threat since Kilauea, one of the world's most active volcanoes, erupted almost two weeks ago.
The news comes amid worsening air quality conditions on the Big Island, and as civil defense authorities continue to respond to Kilauea's ongoing eruptions in lower Puna, where thousands of people remain under mandatory evacuation orders. MORE: Hawaii volcano prompts "ring of fire" fears for West CoastCommunities a mile or two away may be showered by pea-size fragments or dusted with nontoxic ash, they said. They also advised those who are located in the area to avoid unnecessary exposure to ash since it can be both an eye and respiratory irritant.
Officials at the USGS have said that they expect to publish a report on the volcano's activity soon and that the eruption occurred too early in the morning to be captured by video footage.