Kaʻū News Briefs, Thursday, Dec. 15, 2022

Aerial view of the lava flows on the northeast flank of Mauna Loa, taken during a morning overflight on November 29. These lava flows came to within 2 miles (3 km) of the Daniel K. Inouye Highway (Saddle Road) before the eruption ended. USGS photo by M. Patrick

   Prior to November 27, 2022, staff at HVO and Island of Hawai'i residents and visitors alike wondered when and where the next eruption of Mauna Loa would be. Now, with the first eruption in 38 years of Earth's largest active volcano behind us, what have we learned?
   Volcano Awareness Month programs will address this question and others. Join us at one of the events being offered in Hilo, Kailua-Kona, Ocean View, Pu'uhonua o Hōnaunau National Historic Park, and Hawai'i Volcanoes National Park. Or take some time during the month of January to personally reflect on how volcanic activity in Hawai'i can impact you.
   Mauna Loa's recent eruption has reminded Island of Hawai'i residents and visitors that emergency preparedness cannot be overemphasized. An important aspect of preparedness is being aware of the hazards that can impact you where you live but also where you work and your commute. 

   The Mauna Loa eruption threatened the Danial K. Inouye Highway (Saddle Road), a major thoroughfare connecting the east and west sides of the Island of Hawai'i. From the Highway, views of the eruption were spectacular and a stark reminder of how life on the Island of Hawai'i can be impacted very quickly by volcanic activity.

   Fortunately, the lava flow-front stalled, and the Northeast Rift Zone eruption of Mauna Loa ended before the highway was impacted. But consider how your life might have changed had the eruption continued and covered the road. It's important to remember that Mauna Loa's slopes cover more than half of the Island of Hawai'i and future eruptions have the potential to directly impact almost every district on the island. 

The Northeast Rift Zone eruption of Mauna Loa that began the evening of November 27 is considered ended as of December 13. The lava flows came to within 2 miles (3 km) of the Daniel K. Inouye Highway (Saddle Road) before the eruption ended. Map from USGS

   This Mauna Loa eruption accompanied an eruption within Halema'uma'u crater at the summit of Kīlauea. While there were signs that the Kīlauea eruption was waning before the Mauna Loa eruption began, lava supply appears to have ceased for both eruptions within about a day. What does that mean for future volcanic activity?
   We know that the two volcanoes have separate shallow magma systems but it's possible that they influence one another through stresses associated with their eruptions—essentially, when one volcano expands or contracts, it puts pressure on or off the other volcano.
   Though lava supply to Halema'uma'u appears to have paused, passive overturns of the lava lake surface continue as the dense cool crust sinks beneath the hot and buoyant magma below. During these overturns, the molten material beneath Halema'uma'u crater floor is temporarily exposed, making it appear that the eruption has resumed.
   Now, HVO staff and residents are wondering what will happen next? Will Mauna Loa will take another long break or enter a phase of more frequent eruptions? Will the lava lake at Kīlauea summit start to grow again? We'll be monitoring the volcanoes closely for clues and keep you informed.

   We hope to see you at a Volcano Awareness Month program this January. The schedule is forthcoming and will be posted at usgs.gov/hvo, where you can also read volcano updates, view monitoring data, learn geologic histories, see photos and videos, and much more. 

West vent in Halema'uma'u crater and lava lake from a webcam on the northwest rim of the caldera, looking south. USGS photo

Volcano Activity Updates
   Mauna Loa is not erupting. Its USGS Volcano Alert Level is at ADVISORY. Mauna Loa updates are issued weekly on Thursdays.
   Webcam imagery shows residual incandescence and no lava movement in the fissure 3 vent on the Northeast Rift Zone. The inactive main flow front still glows at a few spots at night and may inch northward very slowly as it continues to settle. Sulfur dioxide (SO2) emission rates are at background levels. Summit and Northeast Rift Zone inflation is slowing. For Mauna Loa monitoring data, see: usgs.gov/volcanoes/mauna-loa.
   Kīlauea is not erupting. Its USGS Volcano Alert level is at ADVISORY. Kīlauea updates are issued weekly on Tuesdays.
   Lava supply to the Halema'uma'u lava lake in Hawai'i Volcanoes National Park ceased on December 9. Sulfur dioxide emission rates have decreased to near pre-eruption background levels and were last measured at approximately 200 tonnes per day (t/d) on Dec. 14. Seismicity is elevated but stable, with few earthquakes. Over the past week, summit tiltmeters recorded several deflation-inflation (DI) events. For Kīlauea monitoring data, see usgs.gov/volcanoes/kilauea. 

Map of route for the Discovery Harbour Holiday Parade of Lights this Saturday.

   There was one earthquake with 3 or more felt reports in the Hawaiian Islands during the past week: a M3.3 event 11 km (7 mi) E of Pāhala at 34 km (21 mi) depth on Dec. 14 at 11:45 a.m. HST.
   HVO continues to closely monitor the ongoing eruptions at Kīlauea and Mauna Loa.
   Visit HVO's website for past Volcano Watch articles, Kīlauea and Mauna Loa updates, volcano photos, maps, recent earthquake info, and more. Email questions to askHVO@usgs.gov.