Scientists monitoring the unsettled geological activity on Hawaii’s biggest island say that while an eruption of the volcano that dominates the landscape isn’t yet imminent, Mauna Loa’s long nap may be coming to an end.
The Big Island of Hawaii is really a collection of five volcanoes poking out of the Pacific Ocean, including one of the world’s most active – Kilauea – and the world’s largest: Mauna Loa, making up about half the island’s land mass.
Kilauea has been in the throes of a fiery, dramatic and sometimes destructive eruptive period for decades now. And while the smaller shield volcano on Mauna Loa’s eastern slope garners international attention for its tantrums, its big sibling has been slumbering since it last erupted in 1984.
But over the past week, the Hawaii Volcano Observatory recorded over 200 small magnitude earthquakes below Mauna Loa. These and other observations of increased activity in recent weeks all point to an increased flow of magma into the volcano’s shallow storage system, according to the HVO.
In other words, Mauna Loa is slowly waking up.
While scientists emphasize that an eruption isn’t necessarily going to happen today or tomorrow, this week the HVO put out a release urging that “now is the time to revisit personal eruption plans.”
Particularly vulnerable are areas on the island’s western shore, just south of the main tourism center of Kailua-Kona, where lava flows could reach the ocean and populated areas such as Captain Cook, in a matter of hours.
The most recent eruption of Mauna Loa in 1984 saw lava reach the outskirts of Hilo on the other side of the island – home to the University of Hawaii – but with several weeks warning.
“Nowadays, people pack “go” bags containing essential items in case you have to leave your house under an evacuation order,” reads a statement from the HVO. “You may want to include important documents, like your birth certificate, deeds, legal papers, and medications.”
An eruption does not necessarily mean a threat to people or property though, as half of the eruptions recorded from Mauna Loa have remained contained to the remote summit area. That said, several eruptions have sent lava flowing all the way to the ocean in a matter of mere hours. It’s just hard to predict ahead of time.
Lava eruptions from Kilauea in 2018, which typically produces a lower volume of material compared to Mauna Loa, still managed to destroy a number of homes and other infrastructure.
Aside from lava, eruptions can also produce toxic gases. So in the event of an eruption, be sure to stay up to date with local information from the HVO and Hawaii County Civil Defense to stay safe.