Hi I’m Ali Sealander with UTD GeoNews and today we’re exploring the latest
eruption on the big island of Hawaii.
Our biggest fans might remember our coverage of the eastern rift zone eruption of Kilauea back in
2018. But this time it was Mauna Loa’s turn. This time it was Mauna Loa’s turn.
Native Hawaiians are no stranger to eruptions in the Hawaiian
island chain. There is a deep-rooted spirituality linked to these volcanoes,
and this latest eruption has many thinking that Pele is once again making her presence known
The eruption started November 27, 2022 and was a significant one.
Volcanic activity is common in Hawaii, Mauna Loa alone has erupted 33 times since 1893,
but the last time it erupted was back in 1984.
Mauna Loa is the world’s largest subaerial volcano in terms of mass and volume. And it’s pretty
tall too, it rises 13,679 feet from sea level and a whopping 30,000 feet from the seafloor.
Far below the island of Hawaii the temperatures in the upper mantle are particularly hot.
That’s because there’s an upwelling of hot material from the deep mantle that
geoscientists appropriately call a “hot spot”.
When this upwelling reaches the
lower pressures closer to the surface, the mantle rock begins to melt and form magma.
When the magma reaches the surface, it erupts as a lava. Great build ups of lava in the deep
ocean sometimes rise above sea level and this is how the Hawaiian islands were created.
These islands form a chain with older, more eroded volcanoes farther away from
the active volcanoes of the Big Island. This is because although the mantle hot
spot is stationary the Pacific Plate that lies above it is not.
Imagine holding a lighter underneath a piece of paper that’s moving above it.
The burn marks from the lighter would create a line on the surface of the page.
The big island of Hawaii lies above where the hotspot is now and is made up of 5
major volcanoes, named Kilauea, Mauna Loa, Mauna Kea, Hualalai, and Kohala.
Scientists were clued into the possibility of an eruption back in October when the
rising magma caused a significant increase in small earthquakes underneath Mauna Loa.
Mauna Loa’s 3 mile wide central caldera – Moku‘āweoweo - has two long rift zones emanating
from it to the northeast and southwest. Often the eruptions are confined to this bowl-shaped area,
but other times this lava emerges from one of the two rift zones. This time the lava erupted through
fissures, or cracks, of the northeast rift zone. Some volcanoes erupt explosively and are dangerous
but this eruption, while spectacular, is relatively harmless. The eruption was vigorous
but not explosive because the lava was runny and fairly fluid. This is due to the lava’s
low silica content and high temperatures, which reach 1200 degrees Centigrade or 2000
degrees Fahrenheit. This lava moves fast when it first erupts but slows dramatically as it cools.
The current eruption flowed onto the relatively gentle northeast slopes of the shield volcano and
the nearby town of Hilo was still many miles away. It poses less danger to humans on the island than
if the lava came out of the Southwest rift zone. The slopes on the southwest side of Mauna Loa are
much steeper and could quickly direct lava into the nearby populated Ka‘ū and South Kona areas.
Thankfully this eruption was relatively harmless. The US Geological Survey states that Mauna Loa is
no longer erupting. We don't know what the future has in store for us, but they don't expect Mauna
Loa to erupt again anytime soon. Mauna Loa's eruption was a majestic and awe-inspiring event
and is an incredible example of the natural power that lies just beneath the surface.
I'm Ali sealander with UTD Geo News and I'll see you next time!