Hawai'i Volcano Blog

Mauna Loa Eruption Day 12: Threat to Daniel K. Inouye Highway over for now

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The leading edge of the Mauna Loa eruption has stalled and is currently no longer a threat to Daniel K. Inouye Highway.

The inactive main flow front remains stalled about 1.7 miles from the highway, also known as Saddle Road. As of 7 a.m., activity at the fissure 3 vent significantly reduced producing low fountains that feed lava flows extending only 1.2 miles from the vent. The channels below this point appear drained of lava and probably no longer feed the main flow front.

Image of fissure 3 from live video stream of Mauna Loa eruption Friday, Dec. 9, 2022.

On Thursday, the inactive main flow front inched northward slowly about 7 feet per hour as it settled.

Mauna Loa’s volcanic activity changed drastically over the course of Wednesday night, with expert observers reporting fountains of lava reaching unprecedented heights hundreds of feet in the air. Hawaiʻi Volcano Observatory Scientist-in-Charge Ken Hon said during a press conference this morning, the fountaining dropped Thursday but was still oscillating. As of this morning, lava was only reaching fountain heights of 30 feet.


Hon said the Mauna Loa eruptions can either slow and come to an end or wind down to a sustained low effusion rate. Hon added it is unclear which path Mauna Loa will take at this time.

Tim Orr, geologist with USGS U.S. Geological Survey, said the flow from fissure 3 shifted two nights ago. While it was focused on the western half of the vent, it moved to east end. The flow ultimately shifted back at a much lower discharge rate.

Tremors continue beneath the currently active fissure. According to USGS, this indicates that magma is still being supplied to the fissure, and activity is likely to continue as long as we see this signal.


“The significance of the reduced supply of lava is not yet clear; it is common for eruptions to wax and wane or pause completely,” according to the USGS Friday morning update. “A return to high levels of lava discharge could occur and the Hawaiian Volcano Observatory continues to closely monitor this activity.”

The public parking area to view the lava remains open and will now allow 15-passenger tour vans through the mitigation route on Old Saddle Road starting Saturday.

While the USGS reports indicating a slowing of the flow, Hawai‘i County Civil Defense administrator Talmadge Magno said the county will continue to monitor the area as public interest is still high.


“This is still an active eruption,” Magno added.

Sulfur dioxide (SO2) emission rates were also reduced to approximately 30,000 tonnes per day (t/d) as measured on Thursday. The Hawaii Interagency Vog Information Dashboard has detailed information about vog: https://vog.ivhhn.org/. Forecasts for the dispersion of vog can be found on the VMAP Vog Forecast Dashboard: http://weather.hawaii.edu/vmap/new/.

There is no active lava within Moku’āweoweo caldera nor the Southwest Rift Zone. Experts do not expect any eruptive activity outside the Northeast Rift Zone. No communities are threatened at this time.

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