Hawaiʻi Volcanoes National park – Eruptive Activity Update (September 17, 2025)
An ongoing eruption within a closed area of Hawaiʻi Volcanoes National Park is producing high levels of volcanic gas and volcanic fragments, prompting alerts from the U.S. Geological Survey (USGS). The eruption began recently and, as of September 17, 2025, continues at Kīlauea‘s summit.
The primary hazards are volcanic gas emissions – water vapor (H2O),carbon dioxide (CO2),and sulfur dioxide (SO2) – which create vog (volcanic smog) downwind of Kīlauea. SO2 can cause respiratory problems and other health issues at high concentrations. Details on vog is available at https://vog.ivhhn.org/.
Fallout of Pele’s hair and other volcanic fragments also poses a risk. Pele’s hair, strands of volcanic glass, can be carried over 10 miles (15 kilometers) from the vent. Other glassy volcanic fragments (tephra) – including volcanic ash, pumice, scoria, and reticulite – can fall within 1-3 miles (1-5 kilometers) of the vent, with the highest concentrations promptly downwind. These fragments have previously fallen on Highway 11 west of the park. Pele’s hair can cause skin and eye irritation and contaminate catchment water supplies. further information can be found at https://www.usgs.gov/observatories/hvo/news/volcano-watch-recent-lava-fountains-highlight-peles-hair-hazards and FAQs at https://vog.ivhhn.org/sites/default/files/PelesHair_FAQs_v2.pdf.
Lava flows have been confined to Halemaʻumaʻu crater and the southwest side of Kaluapele, Kīlauea’s summit caldera.
Additional hazards include instability of the Halemaʻumaʻu crater wall, ground cracking, and rockfalls, potentially exacerbated by earthquakes. The Kīlauea caldera rim surrounding Halemaʻumaʻu crater has been closed to the public since late 2007 due to these dangers.
Visitors should consult the Hawaiʻi volcanoes National Park website for current conditions and closures: https://www.nps.gov/havo/index.htm. residents and visitors are advised to minimize exposure to volcanic gas and fragments.
