Kīlauea's latest summit eruption ended last weekend after 6 days, lasting from September 10 to 16, 2023. In that short time it covered nearly 500 acres within the caldera, including a large part of the down-dropped block formed in the 2018 collapse, the eastern rim of the inner crater which now lies buried, and the majority of the inner crater floor.
In a special addition this week, we interview USGS Hawaiian Volcano Observatory Scientist-In-Charge Dr. Ken Hon to discuss the recent eruption.
Gas emissions have plummetted to background levels of 240 tonnes per day, bringing relief to vog-stricken areas in the south and west parts of Hawaiʻi Island, reducing the main threat currently posed by its volcanoes. Even at background levels, volcanic emissions can have significant impacts on sensitive individuals and nearby communities, commonly exceeding industrial standards designed to keep people safe. Still, without lava erupting, gas emissions should remain at the lower end of their range for the near future.
Similar to the previous eruption in June, Kīlauea's main vents erupted lava above the crater floor that then cascaded in, allowing spatter cones to form around the most productive outlets. In June, the 12-day eruption created a cone against the southwest wall of the crater, ponded in the southwest, and covered most of the southwestern down-dropped block. In September, the 6-day eruption left a main cluster of seven large spatter cones with another seven or eight smaller cones scattered upslope, ponded in the east, and covered most of the eastern down-dropped block.
While the volume of lava erupted has not yet been reported for the September eruption, we do know that the southwest sector of the crater floor also rose about 33 feet or 10 meters due to injection of magma below the crust, which must also be accounted for. For comparison, the June eruption resulted in 36 feet or 11 meters of accumulation in the southwest, and was calculated to have output 4.2 billion gallons or 16 million cubic kilometers of lava.
Earthquake and ground deformation rates remain low following the eruption, fitting the common pattern as the volcano recharges quietly underground.
Maunaloa shows no significant change from the expected pattern following its 2022 eruption, refilling its large magma reservoirs and still issuing sporadic deep earthquakes from its feeder conduits. There appear to be no long-term effects from Kīlauea's short eruption on Maunaloa's monitoring streams.
As usual, our live presentation reviews the recent changes using monitoring data, imagery and reports courtesy of the USGS Hawaiian Volcano Observatory. We annotate the presentation on-screen and discuss live viewer questions as we go.
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