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).
The eruption in Hawaii Volcanoes National Park is not threatening downhill communities or flights to the Island of Hawaii, the Hawaii Tourism Authority tweeted Monday morning. Still, a “trace to less than one quarter inch” of ashfall could accumulate on parts of the island, the National Weather Service in Honolulu said, as winds may carry fine ash and volcanic gas downwind.
Reports of lava overflowing into the southwest portion of the volcano’s caldera, or crater, have come in to the Hawaii Volcano Observatory, the Hawaii Emergency Management Agency tweeted late Monday morning.
There is no indication of a threat to nearby communities, and no evacuation orders have been issued, the agency tweeted. As a precaution, two shelters have opened, even as “roughly half” of recorded Mauna Loa eruptions remained in the summit area without threatening populated areas, according to another agency tweet.
“People with respiratory illnesses should remain indoors to avoid inhaling the ash particles and anyone outside should cover their mouth and nose with a mask or cloth,” the Honolulu office warned. “Possible harm to crops and animals. Minor equipment and infrastructure damage. Reduced visibility. Widespread clean-up may be necessary.”
Ashfall can damage vehicles and buildings, contaminate water supplies, disrupt sewage and electrical systems, and damage or kill vegetation, the weather service says, while abrasive volcanic ash can irritate eyes and lungs.
The observatory said earlier that lava flows do not threaten downslope communities.
“Based on past events, the early stages of a Mauna Loa eruption can be very dynamic and the location and advance of lava flows can change rapidly,” the observatory said, adding, “If the eruption remains in Moku’āweoweo, lava flows will most likely be confined within the caldera walls.
“However, if the eruptive vents migrate outside its walls, lava flows may move rapidly downslope.”
Red hues from the eruption illuminated Monday’s predawn sky, according to footage captured at the Kailua Bay & Pier by Matthew Liano, a resident of Kailua-Kona, along the Big Island’s west coast.
“The glow is like nothing I’ve seen here living in Kona for most of my life,” Liano told CNN.
The eruption began in Moku’āweoweo, the summit caldera of Mauna Loa, on Sunday around 11:30 p.m. HST (4:30 a.m. ET Monday), according to the observatory.
Volcano is near Kilauea, which erupted in 2018
Mauna Loa, which covers half the island of Hawaii, has erupted 33 times since 1843, the volcano’s first “well-documented historical eruption” according to the US Geological Survey. It last erupted in 1984, making this prolonged quiet period the volcano’s longest in recorded history.
Mauna Loa’s summit crater sits about 21 miles west of Kilauea, a smaller volcano whose eruption over months in 2018 spewed lava into the Leilani Estates neighborhood, destroying more than 700 homes and displacing residents.
Mauna Loa has been in a heightened state of unrest, per the agency, which pointed in an update late last month to elevated seismic activity and increased earthquake rates.
Earthquake activity increased from five to 10 earthquakes a day since June 2022 to some 10 to 20 earthquakes a day in July and August, according to the US Geological Survey. Peak numbers of more than 100 earthquakes a day were recorded on September 23 and September 29, CNN has reported.
The increased activity prompted Hawaii Volcanoes National Park in October to close the Mauna Loa summit to all backcountry hikers until further notice, though the US National Park Service said the main section of the park has remained open.
Important Facts You Should Know About Mauna Loa
Here are important facts about Mauna Loa, one of the volcanoes that make up the island of Hawaii.
Is Mauna Loa The Only Volcano On Hawaii Island?
The Island of Hawaii is the largest in the Hawaiian island chain and is made up of five volcanoes: Hualalai, Kilauea, Kohala, Mauna Kea, and Mauna Loa. Thanks to these five sisters, the island is highly volatile. Mauna Loa is the largest volcano on earth, while Kilauea is the most active. The volcanic activity of the island means that lava is frequently ejected and cools in the surrounding ocean, effectively expanding the area of the island over time. Talk about a hot spot.
How Old Is Mauna Loa?
Some scientists have calculated the age of Mauna Loa is between 700,000 and a million years old. This means Mauna Loa has been expanding slowly for thousands of years. Molten rock inside the earth’s core, called magma, is forced to the surface by seismic shifting deep inside the earth. The volcano continually grows by spewing this magma out of various cracks in the surface as hot lava that eventually cools when it reaches the sea. The lava hardens and slowly increases the size of the volcano and the island by gradually creating new land. It’s a slow process, but the age of Mauna Loa means that it has had a lot of time to grow. This explains why its high activity has led to it being the largest volcano.
How Big Is Mauna Loa?
The name Mauna Loa translates to Long Mountain in English. Mauna Loa is a true sleeping giant. It’s so large that the sea floor under the mountain has sunk by several kilometers under the weight of this rumbling behemoth. The peak extends 4 kilometers above sea level, another 5 kilometers down to the sea floor, and a further 8 kilometers from the seafloor that has buckled under its weight. That’s a whopping 12 kilometers or 56,000 feet of active monster volcano. In terms of area, it’s bigger than all the other Hawaiian islands combined.
What Lives On Mauna Loa?
An active volcano might sound like an inhospitable place for life to flourish, but that is not the case on Mauna Loa. There are as many vegetation zones on this volcano as there are on the entirety of the Island of Hawaii. As one ascends the mountain below 1,000 feet, the land is characterized by lowland shrubs; between 2,500 feet and 10,000 feet, there are a variety of forest types, and above 10,000 feet, the mountain becomes an alpine stone desert. Mauna Loa is also part of the Mauna Loa-Kilauea Forests Important Bird Area. An array of birds which rely on the volcano’s various vegetation zones as part of their life cycles.
Is It Possible To Hike Mauna Loa?
Perhaps surprisingly, Mauna Loa is usually open to hikers. It’s part of Volcanoes National Park, which also includes the Kilauea Volcano. Mauna Loa is a much harder hike, with high altitudes, difficult terrain, and dangerous conditions. Only expert hikers should attempt the hike. Because this is an active volcano, hikers need to keep abreast of all warnings and advisories on the mountain. The views at the summit and the experience of one of the unique places on earth are well worth the trek.
How Active Is Mauna Loa?
Over the past 3,000 years, on average, Mauna Loa has erupted about once every six years. However, since the 1800s, that sleeping giant has erupted every five years. The last eruption happened in the Spring of 1984. In 2022, Mauna Loa is experiencing a period of unrest, including swarms of earthquakes and physical changes indicative of a possible eruption. It’s quite difficult for geologists to distinguish between a period of heightened activity and precursors of a major eruption because these indicators look pretty much the same when even under the best scientific analysis.
