HVO: Mauna Loa flow is similar to 1984 eruption; Long-term forecast discussed
Update: 2:18 p.m., Nov. 28, 2022
Experts from the Hawaiʻi Volcano Observatory, Hawaiʻi Emergency Management Agency, and government leaders discussed the short- and long-term forecast for the Mauna Loa eruption during an afternoon press briefing hosted by Governor David Ige on Monday.
The eruption started at 11:30 p.m. on Sunday, Nov. 27, and had advanced toward the Northeast Rift Zone by daybreak with three fissures opening up by noon.
Ken Hon, Hawaiʻi Volcano Observatory Scientist in Charge said lava covered almost the entire floor of the summit caldera with a fissure running from the north to the south end. The fissure left the “big caldera,” but stayed in what scientists consider the “summit area” this morning and produced lava flows that were visible from Kona last night. According to Hon, the lava appeared to be headed to the south and west, but only made it a couple of kilometers from the caldera.
At around 5 a.m. the HVO started to pick up lava flows moving to the northeast in an area of seismic activity which also was reported in that area. “We confirmed at 6:30 this morning from overflights that lava flows were moving from fissures that had opened up on the Northeast Rift Zone,” said Hon.
“What this means is the volcanic activity progressed from a summit eruption to a rift zone eruption, and Mauna Loa chose the Northeast Rift Zone to be the locus of eruptive activity. This means, as far as we know in any historic precedence, that there has never been an eruption of Mauna Loa that has activated both rift zones at the same time or during the same eruption. So we presume at this point that all of the future activity will be on the Northeast Rift Zone of Mauna Loa, and not on the Southwest Rift Zone.”
-Ken Hon, Hawaiʻi Volcano Observatory Scientist in Charge
Currently, because the Northeast Rift Zone empties into the Saddle area, Hon said there’s no real risk to habitation up there. He said the Pohakuloa Training Area is outside of where scientists consider any initial lava flows will go. The Mauna Loa Weather Observatory is not directly threatened, but Hon said there is a chance that its road could be cut by these lava flows.
Hon addressed potential long-term impacts as well.
ARTICLE CONTINUES BELOW AD“Eventually, this kind of lava flow is very similar to what happened in 1984, and could potentially threaten populated areas around Hilo. But we’re looking at somewhere around a week before we expect lava to get anywhere near that direction. We’re hoping that it will parallel the 1984 eruption and become more viscous as time goes on… hitting flatter slopes around the Saddle that slow it down.”
–Ken Hon, HVO Scientist in Charge
“Historically this has been the case. Only a couple of eruptions have made it into the outskirts of what is current Hilo,” said Hon. “We’re hoping that this lava flow, while it will be a big spectacular event, it occupies a fairly small proportion of the island, and hopefully it will have relatively minor effects on the residents and visitors to the island.”
HVO scientists also described the fissures saying the eruption has taken place from three different fissures as of noon today. “They are offset a little bit from north to south as we go down the rift zone. They extend from about three quarters of the way toward the summit to about half way to the summit on the rift zone, and they go for somewhere between one and two miles… The fountaining is relatively low–between 100-200 feet along the fissures, and they are putting out gas but not much ash,” said Hon.
Hawaiʻi County Mayor Rich Roth said there are no homes at the current area where the lava flows are at. The 1984 eruption advanced near the Kaumana sub-development, which hasn’t expanded greatly on the upper west side of Hilo, according to emergency management officials.
Talmadge Magno, County of Hawaiʻi Civil Defense Administrator directed the public to the agency’s website for further information and updates.
Luke Meyers, administrator with the Hawaiʻi Emergency Management Agency said, “Weʻre fortunate at this point in time that the lava has went in a bit of a better direction for impacts to people and property.”
He continued saying, “We all must understand that this type of incident can be very dynamic and things can change. We challenge the public over there on the Big Island–visitors and those that live there–to keep their guard up as we move through the rest of this incident.”
“There is pretty heavy SO2 moving north from the volcano, and I know that some of the modeling done shows that plume hitting Maui. That’s going to be a fact of life,” said Hon. “Typically these eruptions last for a one to two weeks–someplace in there–so we’re probably going to have a deterioration of air quality during that time period.”
Hon said the timeline of two weeks is based on historical record and the average of previous events, and is a “best guess.” Out of the 33 documented eruptions at Mauna Loa, the longest has lasted more than a year, and the shortest, just a couple of days, according to experts.
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