Volcanic pyrotechnics: Mauna Loa is back

 

It’s been a while since the night sky over the highest parts of Hawai’i Island were lit bright orange by something other than the sun.

(The image above, an aerial USGS photo taken early Dec. 6 by L. Gallant, displays fountains at Mauna Loa Fissue 3. The fountains are running at 40 meters on average, with bursts to 100 meters.)

The new eruption of Mauna Loa is filling those skies—and the internet—with stunning shots of blazing fountains, glowing clouds and sinewy Halloween-colored lava flows.

Mauna Loa took a pause after its two-volcano show with Kīlauea in 1984. It was a long pause by Mauna Loa standards. The big volcano—the biggest one in the world—has erupted every five years or so since the early 1800s, and once every 6 years over the last few millennia. So a 38-year quiet is quite something.

There used to be arguments among volcano folks about whether the underground plumbing made it even possible for Mauna Loa and Kīlauea to erupt at the same time. They did in 1984, and again now, so that’s settled. They generally do not erupt together, but they can.

The new mystery is whether it’s possible for Mauna Loa, Kīlauea AND the younger volcano Kama’ehuakanaloa to erupt at once. As far as we know, that has not yet happened.

Kama’ehuakanaloa, formerly known as Lō’ihi, lies in the waters 20+ miles east of Nā’alehu. It is not currently erupting, although occasional swarms of earthquakes show that there’s magma moving under that seamount. We’ll see.

And might it be possible for concurrent eruptions of those three plus Hualalālai, which last erupted in 1801, and isn’t done yet. Mauna Kea and Haleakalā eruptions are also possibilities, but all three seem to be geologically napping at this time.

Mauna Loa’s eruptive phases tend to be big shows, but short ones. They range from a few days or weeks to as much as a year. That’s short compared to Kīlauea’s, which can go on for decades, but which produce far less lava.

Mauna Loa’s flows can run to the sea very quickly down sloping ground, depending on the direction they take. During the past two centuries they have reached the shoreline in North Kona, South Kona and Ka’ū, and made it to the outskirts of Hilo. Mauna Loa flows have reached from the eruption site to the coast, tens of miles away, in as little as a few hours.

That’s not happening right now, largely because the 2022 eruption is currently flowing into the flattish lands of the saddle between Mauna Loa and Mauna Kea, but if the eruption continues, and the lava spills out into steeper slopes, it could get moving pretty quickly.

As this is written, the hot lava is less than two miles from the old Saddle Road, now the Daniel K. Inouye Highway. If that cross-island artery is cut, disruptions for residents will be significant.

Mauna Loa’s lava production has been estimated at an estimated 100 cubic meters per second. (By my calculations, that would fill an average Hawai’i house every couple of seconds, an average apartment building every couple of minutes.)

 If you’re interested in this eruption, the National Park Service has an information site here, and it includes lots of links to other sources of information. 

© Jan TenBruggencate 2022