The world鈥檚 largest active volcano spewed some ash and lava Monday and officials warned residents of Hawaii鈥檚 Big Island to prepare for a possible larger eruption.
The U.S. Geological Survey warned the island鈥檚 200,000 residents that an eruption of Mauna Loa 鈥渃an be very dynamic, and the location and advance of lava flows can change rapidly.鈥�
The eruption began late Sunday night in the volcano on the Big Island following a series of closely spaced, fairly large earthquakes, said Ken Hon, the scientist-in-charge at the Hawaiian Volcanos Observatory. Magma moved to the surface, although lava flows were contained within the summit area and weren鈥檛 threatening nearby communities.
There鈥檚 been a surge of development on the Big Island in recent decades 鈥� its population has more than doubled to 200,000 today from 92,000 in 1980 鈥� and many newer residents weren鈥檛 around when Mauna Loa last erupted 38 years ago.
Most of the people on the island live in the city of Kailua-Kona to the west of the volcano, which has about 23,000 people, and Hilo to the east, with about 45,000. Officials were most worried about several subdivisions about 30 miles to the south of the volcano, which are home to about 5,000 people.
A time-lapse video of the eruption from overnight showed lava lighting up one area, moving across it like waves on the ocean.
The eruption migrated from the summit to the northeast rift zone, a notice from the U.S. Geological Survey said. A rift zone is where the mountain is splitting apart and the rock is cracked and relatively weak - making it easier for magma to emerge.
The eruption Monday was feeding several lava flows, which were not threatening any downslope communities. All indications pointed to the eruption staying in the northeast hazard zone, the USGS statement said.
An eruption from the northeast rift zone could send lava toward the county seat of Hilo or other towns in East Hawaii. It could take lava weeks or months to reach populated areas on this side of the mountain.
鈥淲e don鈥檛 want to try and second guess the volcano,鈥� Hon said. 鈥淲e have to let it actually show us what it鈥檚 going to do and then we inform people of what is happening ASAP.鈥�
Hawaii County Civil Defense announced it has opened shelters in Kailua-Kona and Pahala because it has reports of people self-evacuating along the coast.
The average Mauna Loa eruption is not typically prolonged, lasting a couple of weeks, Hon said.
鈥淭ypically, Mauna Loa eruptions start off with the heaviest volume first,鈥� Hon said. 鈥淎fter a few days, it starts to calm down a little bit.鈥�
The USGS warned residents at risk from Mauna Loa lava flows to review their eruption preparations. Scientists had been on alert because of a recent spike in earthquakes at the summit of the volcano, which last erupted in 1984.
鈥淎t this time, it鈥檚 not a time to be alarmed,鈥� Big Island Mayor Mitch Roth said.
Portions of the Big Island were under an ashfall advisory issued by the National Weather Service in Honolulu, which said up to a quarter-inch (0.6 centimeters) of ash could accumulate in some areas.
Mauna Loa is one of five volcanoes that together make up the Big Island of Hawaii, which is the southernmost island in the Hawaiian archipelago.
Mauna Loa, rising 13,679 feet (4,169 meters) above sea level, is the much larger neighbor of Kilauea, which erupted in a residential neighborhood and destroyed 700 homes in 2018. Some of its slopes are much steeper than Kilauea鈥檚, so lava can flow much faster when it erupts.
During a 1950 eruption, the mountain鈥檚 lava traveled 15 miles (24 kilometers) to the ocean in fewer than three hours.
Tourism is Hawaii鈥檚 economic engine but Roth predicted few problems for those on vacation during the eruption.
鈥淚t will be spectacular where it is, but the chances of it really interrupting the visitor industry 鈥� very, very slim,鈥� he said.
For some, the eruption might cut down on some travel time, even if there is more vog, or volcanic smog caused by higher sulfur dioxide emissions.
鈥淏ut the good thing is you don鈥檛 have to drive from Kona over to Hawaii Volcanoes National Park to see an eruption anymore,鈥� Roth said. 鈥淵ou can just look out your window at night and you鈥檒l be able to see Mauna Loa erupting.鈥�
Julia Neal, owner of Pahala Plantation Cottages, said the eruption brings some relief after many preparedness meetings, and much wondering about what the volcano will do.
鈥淚t鈥檚 exciting,鈥� she said. 鈥淚t鈥檚 kind of a relief that it鈥檚 happening and we鈥檙e not waiting for it to happen.鈥�
News that the eruption migrated from the summit to the northeast rift zone and that lava isn鈥檛 threatening any downslope communities also brings relief, she said.
A few future guests from the U.S. mainland called Neal 鈥渁sking me to make a prediction, which I can鈥檛,鈥� she said. 鈥淪o I said, just stand by.鈥�
鈥擟aleb Jones, The Associated Press
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