Mauna Loa, the world’s largest volcano, may be waking up

PAHOA, HI - MAY 24: Kate Lilly (L) and Will Divine watch as lava erupts from a fissure in Kilauea volcano in Leilani Estates, Hawaii

Mauna Loa stirs. This week, other “swarms” of small earthquakes rocked the Hawaiian peak, following increased seismic activity at the summit for months. These earthquakes may mean the world’s largest volcano is waking up, which could mean Mauna Loa’s first eruption since 1984.

Now you might be thinking, “Hey, didn’t the Hawaii volcano have a major eruption just a few years ago?” Isn’t it erupting, sort of now? And yes, you are right, Kīlauea is currently in an active eruption and has been for many decades. And there was a huge eruption in 2018 (pictured) that razed an entire residential neighborhood and displaced 2,000 people while adding more than 800 acres of land to the Big Island. But Kīlauea is not the same as Mauna Loa.

The Big Island of Hawaii is made up of five separate volcanoes: Kīlauea, Mauna Loa, Mauna Kea, Hualālai and Kohala. Kohala is extinct and Mauna Kea is classified as dormant and has not erupted for several thousand years, but the rest of the volcanoes are still active, including a sixth volcano still underwater, Lō Seamount ‘ihi.

Kilauea is the most active volcano in the world and was home to a continuous eruption at Puʻu ʻŌʻō crater from 1983 to 2018. On the other hand, Mauna Loa, which is half of the big island, is the largest mountain of the world. and the largest active volcano. It has erupted 33 times since 1843 but has not seen any eruption or active lava flow from the summit crater, known as Moku’āweoweo Caldera, since 1984.

All of this activity, and indeed the entire existence of the Hawaiian Island Chain, is due to the Pacific plate of the Earth’s crust slowly drifting through a hotspot in the Earth’s mantle by a few inches per year, which is about 32 miles per million years. Magma rising from the hot spot pushes up and out of Hawaii’s shield-type volcanoes, constantly expanding the islands. As the magma and gases beneath the volcanoes rise and release, it moves the earth. So more earthquakes are an indicator of another possible eruption. Before the previous eruptions, there were large seismic peaks.

The Mauna Loa eruption in 1984 was massive and intense, with lava flows threatening the Big Island’s largest population center, the city of Hilo. The lava stopped just 7 miles from town which was lucky. Now that Mauna Loa is stirring again, the USGS Hawaiian Volcano Observatory reminds residents that “now is the time to review personal eruption plans. Similar to preparing for hurricane season, having a blowout plan in advance helps in an emergency. “

And depending on where and how an eruption on Mauna Loa occurs, there is a big difference in how quickly lava flows could reach different areas, as shown in this map from the USGS.

Color map of lava flow response timesNow, the seismic activity on Mauna Loa at this time is nothing compared to 1984, or other eruptions… yet. But with these volcanoes, it’s really a matter of “when” and not “if” they will erupt again, given the continued activity on Mauna Loa, as well as other Hawaiian volcanoes.

It’s worth noting that we can’t even be sure where a lava flow might have come from. The lava flows from the Kilauea eruption in 2018 did not come from the famous crater but from dozens of cracks that opened in a residential area. Scientists can hope to predict and prepare for these eruptions and warn people to stay alert, but there is a saying in Hawaii about the volcano goddess that was shared with me by a friend who has studied volcanoes there. below: “Pele goes where she wants.” When Pele starts to move, all we can do is step aside and hope she gives a warning.

(via: Maui Now, Image: Mario Tama / Getty Images)

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