Mauna Loa (USGS)
Copyright © 2022
by Ralph F. Couey
It was a relatively quiet Sunday evening. There was no weather to speak of, no other event on-going, though we had been monitoring the earthquake activity at Mauna Loa. About 10:30 PM, the monitor we have for the California Integrated Seismic Network sounded it's familiar alarm. CISN monitors earthquake activity around the world, and sends us alerts, which happens several times during a watch. Most people don't know what a restless planet we live on. If an earthquake larger than magnitude 6.5 occurs anywhere within the Pacific Basin, we go to a higher alert posture until the Pacific Tsunami Warning Center evaluates the incident in case a tsunami was generated.
Local earthquakes are a different matter. The Big Island, Hawai'i, is home to no less than four active volcanoes. Mauna Kea, where all the expensive telescopes are, Hualalai, Kilauea, and Mauna Loa. There is also an active volcano on Maui, called Haleakala, and one offshore of the Big Island, Loihi. This one is an undersea volcano which will break the sea surface in about 100,000 years. All of the activity has been on the Big Island. Kilauea has been erupting since September 29th of last year, the effused lava confined to the summit caldera.
But the Big Island is a special case. A strong enough earthquake might break loose the southeast flank of the island and send the Manhattan-sized mass sliding into the ocean, generating a tsunami. So, anything north of magnitude 3.5 gets our attention. On the night in question, the first quake, a magnitude 4.5 came in at about 10:55 PM. PTWC assessed almost immediately that there was no tsunami threat. Then about an hour later, another earthquake rumbled, this one a magnitude 4.1. Shortly after that, we received a telephone call from the island's Civil Defense, reporting that Mauna Loa was erupting.
Although my watch team was due to leave at midnight, we stayed to help the midnight crew handle things. It was a long night, as we didn't leave until things finally calmed to a manageable level at 4:45 AM. The state Emergency Operations Center, an old artillery bunker in Diamond Head crater, went to full activation, which is where we've been since. Sunday will mark two weeks since the eruption started. At first, the eruption was confined to the summit caldera. The next day, the eruption moved into the northeast rift zone, probably the safest direction.
Since then, the volcano has remained active, the fountains seen on the USGS YouTube site are spectacular, especially during the day when the vivid red of the erupting magma is visible. Lava flowed downhill towards the Daniel K. Inouye Highway, a vital link for Big Island residents. There was a concern that the lava could cover and block the road, but in the past two days, a breakout flow occurred further uphill, and that seems to have taken the steam out of the threatening flow, stalling 1.7 miles from the highway.
Park Service and law enforcement have been busy trying to keep people, mainly tourists, out of danger. Several arrests have taken place. There are also those who have been desecrating the mountain, which is a sacred site for native Hawai'ians. Three people were busted after throwing marshmallows into the lava flow.
There hasn't been a lot of ash, but what there has been was something called Pele's hair. This is actually fine strands of volcanic glass that wafts out of the volcano and travels great distances on the winds.
National Park Service
While it looks pretty, its dangerous if inhaled. Touching it can result in getting small glass slivers in your skin. Authorities have recommended masks for those in the affected areas.
Aside from the obvious awe factor, watching this volcano erupting reminds one of the power of nature, and how minimal humans are when compared. Most people don't know, but Mauna Loa is the tallest volcano on the planet, but there's more to this than meets the eye. The summit rises to 13,679 feet from the surface of the ocean. But there's five miles of the volcano between the ocean surface and the floor. And if that wasn't enough, the enormous weight of the mountain has pushed itself five more miles below the ocean floor. From there to the top, it's about 55,000 feet, the tallest by a fair margin.
The eruption continues, and as no communities are in danger, it has become the biggest attraction. This is an unusual time, because Mauna Loa's neighbor Kilauea, is also erupting, something that last occurred in 1984.
Nobody knows how long this will last, but it will be a hot ticket here as long as it does.
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