The world’s largest active volcano was erupting Monday and wasn’t immediately threatening communities on Hawaii’s Big Island, but officials warned residents to be ready for worse. Many current residents weren’t living there when Mauna Loa last erupted 38 years ago. The US Geological Survey warned the roughly 200,000 people on the Big Island that an eruption “can be very dynamic, and the location and advance of lava flows can change rapidly.”
The eruption began late Sunday night following a series of fairly large earthquakes, said Ken Hon, the scientist-in-charge at the Hawaiian Volcano Observatory.
There’s been a surge of development on the Big Island in recent decades – its population has more than doubled, from 92,000 in 1980.
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 US Geological Survey said that the eruption had migrated to a rift zone – a place where the mountain rock is cracked and relatively weak – making it easier for magma to emerge.
An eruption from the zone could send lava toward the county seat of Hilo or other towns in East Hawaii but it could take the lava weeks or months to reach populated areas.
“We don’t want to try and second-guess the volcano,” Hon said. “We have to let it actually show us what it’s going to do and then we inform people of what is happening ASAP.”
Hawaii County Civil Defense announced that it had opened shelters because it had reports of people evacuating from along the coast on their own initiative.
The average Mauna Loa eruption is not typically prolonged, lasting a couple of weeks, Hon said.
“Typically, Mauna Loa eruptions start off with the heaviest volume first. After a few days, it starts to calm down a little bit.”
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.
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’s, so lava can flow much faster when it erupts.
Tourism is Hawaii’s economic engine but Roth predicted few problems for those on vacation during the eruption.
“It will be spectacular where it is, but the chances of it really interrupting the visitor industry -very, very slim,” he said.
Meanwhile here is a Q&A that answers any questions about travel to Hawai’i at this time.
Q: Should travel plans to the Hawaiian Islands be postponed or cancelled?
A: There is no need to change travel plans to any of the Hawaiian Islands at this time. Mauna Loa is located on Hawai‘i Island, the southernmost island of the main island chain. Travel to the other islands – Kaua‘i, O‘ahu, Maui, Moloka‘i and Lāna‘i – is unaffected by the eruption.
Q: Should travel plans to Hawai‘i Island be re-routed to the other islands?
A: There is no need to change travel plans to Hawaiʻi Island at this time. The eruption of lava is currently contained within the summit caldera at the top of Mauna Loa. While the eruption has caused Mauna Loa’s Aviation Color Code to be elevated to red – which means a hazardous eruption is imminent, underway or suspected – Hawai‘i Island’s two major airports in Hilo and Kona are currently open and the eruption is not expected to affect their ability to handle the regularly scheduled flights that arrive and depart each day. It’s a good idea to check with your airline for the status of your flight.
Q: Is this eruption a danger to people on Hawai‘i Island?
A: While all lava being emitted is currently contained within the summit caldera at the top of Mauna Loa, volcanic eruptions are dynamic and conditions can change quickly. Residents and visitors staying in communities downslope of Mauna Loa should have emergency preparedness plans ready in the event an evacuation becomes necessary. Visitors staying in short-term vacation rentals should contact their hosts for more information. The major resort areas of Kailua-Kona, the Kohala Coast, and Hilo are not immediately downslope of the eruption.
Q: Is there a danger to people with breathing problems from the ash emitted by the eruption?
A: People who suffer from asthma, emphysema, COPD, or other types of breathing problems should take precautions to avoid the ash and vog (a form of volcanic smog) that are characteristic of volcanic eruptions. This would include either staying indoors or monitoring how the wind is blowing so as not to be caught in an area where ash and vog are heavy and could impair the ability to breathe normally.
Q: Is this eruption of Mauna Loa unusual?
A: While Hawai‘i Island is the youngest and most active of the Hawaiian Islands in terms of volcanic activity, eruptions are rare. The last time Mauna Loa erupted was 38 years ago in 1984. The island’s most recent eruption took place in 2018 when Kīlauea Volcano erupted and lava flowed for several months.
Q: Where can people find the latest information and updates on the eruption?
A: Official channels are the best sources for the latest updates about the Mauna Loa eruption, including the following:
• Hawaiian Volcano Observatory: https://www.usgs.gov/observatories/hvo
• Hawai‘i Emergency Management Agency: https://dod.hawaii.gov/hiema/
• Hawai‘i County Civil Defense: https://www.hawaiicounty.gov/departments/civil-defense