Mauna Loa, the largest volcano on Earth. erupts in Hawaii

(US Geological Survey http://bit.ly/3EPUQAb)
After almost 40 years of silence, the largest active volcano on Earth, Mauna Loa, began to erupt.

The first lava fountains were ejected inside the summit caldera on November 27. Then, the center of the eruption moved to a fissure zone on the northeastern slope of the volcano.

The volcanic Hawaiian Islands create intense intraplate magmatism in the hotspot region over which the Pacific Plate moves.

Moving along with the plate to the northwest, the island-volcanoes "move out" from the stationary hot spot, stop growing and gradually collapse.

Their remains stretch in the form of an underwater ridge to the edge of the Aleutian Trench.

Above the area of ​​active magmatism is the southeastern part of the island of Hawaii (the youngest in the archipelago) and a section of the ocean floor next to it.

The underwater volcano Kamaehuacanaloa grows here, and in the southeast of the island there is the extremely active Kilauea and the largest active volcano on Earth: Mauna Loa.

This giant is a flat profile volcanic shield edifice typical of the Hawaiian Islands with a maximum steepness of 12 degrees, formed by low-viscosity basaltic lavas.

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MAUNA LOA
The surface part of Mauna Loa occupies 5100 square kilometers, that is, about half of the island of Hawaii

The volcano rises to 4169 meters above sea level, and together with the underwater part, its height exceeds nine kilometers.

The age of the volcano is from 0.6 to 1 million years, and during this time it has accumulated about 75 thousand cubic kilometers of solid products.

The top of the Mauna Loa lava shield is crowned by a collapse caldera called Mokuaveoweo, measuring 6.2×2.5 kilometers and up to 180 meters deep.

From it, in the northeast and southwest directions, systems of cracks descend, through which lava often poured out.

The last eruption of Mauna Loa occurred in 1984.

It lasted three weeks and proceeded according to a typical scenario for this volcano:

• first, the flowing lava filled the caldera
• then the activity shifted to the slope, into the fissure system

During the 1984 eruption, the volume of ejected material was 0.22 cubic kilometers; and the lava covered an area of ​​48 square kilometers.

After that, Mauna Loa remained calm for a relatively long time and only in 2002 showed the first signs of another awakening: vertical displacements of the surface and an increase in seismic activity.

These phenomena have recurred several times and have intensified since the end of September 2022.

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THE NEW ERUPTION
On November 27 at 11:30 p.m. Hawaiian-Aleutian Standard Time, the webcams of the Hawaiian Volcanic Observatory recorded how lava began to gush from cracks that opened in Mokuaveoweo and spread along the caldera floor.

The eruption was assigned a red (highest) alert level on the aviation color code scale.

The risk for aircraft is associated with the ingress into the atmosphere of filamentous fibers of volcanic glass, as well as with possible ash and gas emissions.

These emissions can disable aircraft jet engines.

The NOAA GOES-West geostationary satellite captured a thermal anomaly and a release of sulfur dioxide from the Mokuaveoweo caldera.

According to the Volcanic Ash Advisory Center in Washington, the height of the eruptive cloud reached 13.7 kilometers.

The eruption developed in a mode characteristic of Mauna Loa.

During the night, lava continued to fill the caldera, and already at 06:30 in the morning, the center of the eruption had migrated from the summit to the northeastern fissure zone.

Lava flows flowed down the slopes in its upper part, slightly higher than the location of the weather observatory (located at an altitude of 3397 meters, about 6 kms from the caldera).

Initially, three fissures actively erupted lava, but as of 13:30 on November 28, only the lowest one, at an altitude of about 3000 meters, remained active.

It ejects lava on average to a height of several meters, but individual fountains reach 60 meters.

The lava flows in an easterly direction while the gas plume drifts to the northwest.

Currently, none of the settlements near Mauna Loa is in immediate danger.

However, according to volcanologists, the possibility of opening new cracks is not ruled out.

And in this case, the lava can go down the northern slope and reach the highway, from which it is now separated by about 18 kilometers.

Sources:

• USGS: https://www.usgs.gov/volcanoes/mauna-loa/mauna-loa-eruption-webpage
• BBC: https://www.bbc.com/news/world-us-canada-63783633

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