Activity Summary: Increased seismicity and ground deformation near Makaopuhi Crater in Hawai'i Volcanoes National Park indicate an ongoing magmatic intrusion in this portion of the middle East Rift Zone (MERZ) since September 14. A very small eruption occurred in the area yesterday evening, September 15, and unrest currently continues. Because these signals have not dissipated following last night's eruption, renewed episodes of intense unrest or eruption are possible and could occur with little warning. For this reason, the Volcano Alert Level/Aviation Color Code will remain at WATCH/ORANGE for the present time. All current and recent activity is within Hawaiʻi Volcanoes National Park; no changes have been detected in the lower East Rift Zone or Southwest Rift Zone.
About 80 earthquakes were detected in the MERZ since this morning's update at 9 AM. Weak tremor that was detected on MERZ seismometers beginning yesterday afternoon is also on-going.
Rates of deformation have been steady through the day with about the same modest amount of tilt measured today as yesterday. However, daily position solutions from GPS instruments have shown displacements of over 20 cm (8 inches) for several stations in the MERZ. The largest displacement is for station MKAI, just downslope of Makaopuhi, which experienced 54 cm (1.8 feet) of south-southwest motion since September 14. The combination of large GPS displacements and modest tilt rates suggests that much of the deformation is the result of magma entering a storage region several kilometers (1-2 miles) below the surface.
HVO is continuing to closely monitor the middle East Rift Zone and is in contact with Hawai'i Volcanoes National Park and the Hawai'i County Civil Defense Agency. Temporary closures have been implemented as a result of this elevated activity; please see the Hawaiʻi Volcanoes National Park website for visitor information: https://www.nps.gov/havo/index.htm.
Eruption Summary: Kīlauea volcano erupted briefly last night, September 15, 2024, on a remote section of the middle East Rift Zone in Hawaiʻi Volcanoes National Park, just west of Nāpau Crater. This eruption, which is now over, likely occurred between approximately 9 PM and 10 PM HST, when infrasound instruments detected a strong signal typical of gas or steam venting.
A helicopter overflight this morning revealed that small lava pads erupted from two fissure segments extending 480 meters (525 yards). The lava reached about 90 meters (100 yards) away from the fissure vents, covering approximately 2 hectares (4 acres) in total. The total volume erupted is estimated to be about 20,000 cubic meters (25,000 cubic yards), which is roughly equivalent to 8 Olympic-sized swimming pools. Vegetation in the immediate eruption area was burned and sulfur dioxide continues to degas from the vents. The eruption did not pose a threat to human life or infrastructure, however it occurred in close proximity to the Nāpau Trail and cultural resources nearby.
Degassing of sulfur dioxide from the fissure system has continued since the eruption, with a rate of 300 +/- 50 tonnes/day measured by field crews between 11:30 AM and 1:30 PM HST today. It is likely that rates were higher during the eruption and immediately after, but it is not possible at this time to estimate by how much. At higher levels, gas emissions can pose a hazard to humans downwind of the eruption site. Chain of Craters Road, which is closed, is located downslope and downwind of the new fissures.
A reference map of the middle East Rift Zone, with past lava flow extents, is available here: https://www.usgs.gov/maps/kilauea-middle-east-rift-zone-reference-map.
For more information about the meaning of volcano alert levels and aviation color codes, see https://www.usgs.gov/programs/VHP/volcanic-alert-levels-characterize-conditions-us-volcanoes.