An eruption began in the summit caldera of Hawaii's Mauna Loa, the world's largest active volcano, on the night of 27NOV, the U.S. Geological Service's (USGS) volcanic activity service said.
The volcano alert level has been upgraded from an "advisory" to a "warning."
A notification indicates that based on previous events, the early eruption stages of this volcano can be very dynamic and the location and advance of lava flows can change rapidly. The notification added that the Hawaiian Volcano Observatory (HVO) would conduct aerial reconnaissance as soon as possible to assess hazards and better describe the eruption. Over a dozen earthquakes of more than 2.5 magnitude struck the region, according to the USGS, with one measuring 4.2 in magnitude.
"At this time, lava flows are contained within the summit area and are not threatening downslope communities," the USGS said in a news release. "Winds may carry volcanic gas and possibly fine ash and Pele’s hair downwind," it said, referring to a type of lava.
The USGS previously said that “heightened unrest” began in mid-SEP, when earthquakes beneath the summit increased from 10 to 20 per day to 40 to 50 per day. That unrest prompted Hawaii Volcanoes National Park to close the summit backcountry until further notice, it reported.
"Hawaiian lava flows have rarely caused human fatalities, but they can cause extensive damage by covering, burning, and crushing anything in their paths, or starting secondary fires," according to the agency, which adds that interactions between water and lava "can also sometimes be explosive in coastal environments."
Mauna Loa, which takes up more than half of the Big Island in Hawaii, and rises 13,679 feet (4,169 meters) above the Pacific Ocean, last erupted in March and April of 1984, sending a flow of lava within 5 miles (8.05 km) of the city of Hilo.