In pics: World’s biggest active volcano erupts after 38 years

The U.S. Geological Survey’s Hawaiian Volcano Observatory increased the alert level for volcanic activity to “warning”, which is of the highest magnitude.
Deena Theresa
Lava fountains along a fissure on Mauna Loa's Northeast Rift Zone at approximately 9:30 am HST on November 28, 2022.
Lava fountains along a fissure on Mauna Loa's Northeast Rift Zone at approximately 9:30 am HST on November 28, 2022.

K. Lynn/USGS 

When Mauna Loa, the world's largest active volcano, erupted in 1984, not many people were living on Hawaii's Big Island. 

Almost 40 years later, on Sunday, November 27, 2022, around 11:30 pm local time (09:30 GMT Monday) Mauna Loa began erupting, spewing lava and smoky ash, casting a fiery red glow over Hawaiian skies. This time, to the roughly 200,000 people on the Big Island — more than double since 1980 — the U.S. Geological Survey (USGS) warned that eruption "can be very dynamic, and the location and advance of lava flows can change rapidly".

In pics: World’s biggest active volcano erupts after 38 years
Aerial photos taken at 7:15 AM local time (HST) from Civil Air Patrol flight. Northeast rift zone eruption of Mauna Loa.

The USGS's Hawaiian Volcano Observatory (HVO) increased the alert level for volcanic activity to the highest "warning", from "advisory". HVO also stepped up the aviation threat level from "yellow" to "red" to highlight the presence of airborne gases, ash particles, and "Pele's hair" volcanic glass fibers, as per a statement.

Though no property is at risk currently, a gas plume from the erupting fissure fountains and lava flows is visible, with the plume primarily being blown to the Northwest.

Mauna Loa has erupted 33 times

Since 1843, which was Mauna Loa's first well-documented historical eruption, the volcano has erupted 33 times. The massive volcano rises 13,679 feet (4,169 meters) above the Pacific Ocean and is part of the many volcanoes that formed the islands of Hawaii - it forms 51 percent of the island of Hawaii, according to the U.S. National Park Service.

When it erupted in March and April of 1984, the eruption lasted for 22 days and sent a flow of lava within five miles (8.05 km) of Hilo, the island's largest city, Reuters reported.

The latest eruption was not unprecedented - it comes after weeks of frequent earthquakes at the summit of the volcano, and seismic activity that was reported in September. Such harbingers had prompted officials to ask residents to prepare for an evacuation, reported Hawaii News Now

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In pics: World’s biggest active volcano erupts after 38 years
Mauna Loa eruption as viewed from Waikoloa at about 1:25am local time (HST). The eruption is occurring from the summit of the volcano, though lava has overflowed the caldera.

Lava flows mostly contained within the summit's caldera

A USGS webcam on Mauna Loa summit's north rim revealed long bright eruptive fissures within the volcanic crater, contrasted against the dark of night.

This time, lava flows were mostly contained within the summit's massive caldera and an advisory for ashfall was issued for the surrounding area overnight. It has since been lifted.

In pics: World’s biggest active volcano erupts after 38 years
Image from Mauna Loa summit webcam acquired at 11:46 PM HST.

"These lava flows rarely present a risk to life, but they can be extremely destructive to infrastructure," Dr. Jessica Johnson, a British volcano geophysicist who has worked at the Hawaiian Volcano Observatory, told BBC News.

If magma begins to pour out of the so-called rift zones along the volcano's flanks, it would pose a large threat.

Johnson added that the lava flows could pose a risk to Hilo and Kona, creating breathing problems for the local population.

In terms of carbon emissions, according to USGS data, Mauna Loa released around 15,000 tons of carbon dioxide during its last eruption. Nevertheless, scientists said that all of Earth's volcanoes combined emit less than one percent of the carbon dioxide produced by humans every year.