Kaʻū News Briefs Friday, Sept. 15, 2023

USGS RELEASED THIS UPDATE FOR ONGOING ERUPTION AT HALEMA‘UMA‘U ON FRIDAY: 

    Activity Summary: The Kīlauea summit eruption that began on September 10th continues Friday morning. Eruptive activity is confined to the downdropped block and Halemaʻumaʻu crater within Kīlauea’s summit caldera. No unusual activity has been noted along Kīlauea’s East Rift Zone or Southwest Rift Zone.
    Summit Eruption Observations: Several roughly east-west oriented vents continue to erupt on the western side of the down-dropped block within Kīlauea’s summit caldera and are generating lava flows

A row of scones in Halema‘uma‘u are actively ejecting spatter, which helps build the height of each structure. Cone heights of 20 meters (66 feet) have been measured by field teams. Of the line of vents spanning 0.8 miles (1.4 km) that were observed active during the initial phases of the eruption, only six remain active as of September 14, 2023. USGS photo by L. Gallant

onto Halema‘uma‘u crater floor. Effusion rates continue to decrease, but remain significant.

• Vigorous spattering is restricted to the westernmost large spatter cone with fountains 10-15 meters. Minor spattering is occurring within the next cone to the east, but the fountains remain mostly below the rim of its cone. Lava continues to flow from these and potentially several of the other cones.
• Pāhoehoe lava flows continue to travel in north and west directions from the vents, around elevated ground from the 1982 eruption, and onto Halema‘uma‘u crater floor. Overnight on Thursday, webcam imagery shows that the area of active lava remains restricted to the western part of the downdropped block and the northeastern parts of Halema‘uma‘u. This area of active lava does not appear to have changed significantly in size over the past 24 hours. Numerous oozeouts of lava were visible over other parts of Halema‘uma‘u crater floor overnight.
• Field crews Thursday reported that lava fountain heights at the vents reached up to about 10-15 meters (32-50 feet) and the horseshoe-shaped spatter ramparts that have accumulated on the south/downwind side of the vents remain 20 meters (66 feet) high.

Much of the plume from Kīlauea’s current eruption is sulfur dioxide (SO2). HVO’s gas monitoring station HRSDH has measured up to 12 ppm of SO2 at its location, nearly 2 miles (3 km) southwest, downwind of the eruption. According to the International Volcanic Health Hazard Network (IVHHN), prolonged exposure to SO2 in these concentrations is toxic. Even brief exposure to concentrations less than that will cause a respiratory response (airway resistance) and eye irritation. Concentrations more than that cause paralysis or death with extended exposure. SO2 mixes with air as it moves away from the vent and is less of a hazard for people keeping a safe distance. While the trade winds transport plumes in a southwest direction most of the time, conditions can change rapidly, especially in areas closer to the vent that remain closed to the public. USGS photo by M. Patrick

• The laser rangefinder is aimed at a western portion of Halema‘uma‘u, not near the new eruptive activity, and recorded about 10 meters (33 feet) of uplift to this locality since the eruption started. This demonstrates that a significant amount of lava has intruded beneath the pre-existing crust within Halema‘uma‘u.
• Volcanic gas emissions in the eruption area are elevated; winds yesterday, September 14, prevented measurements of a suflur dioxide (SO2) emission rate. The most recent SO2 emission rate of 20,000 tonnes per day was measured the afternoon of September 13. This is down significantly from the 190,000 tonnes per day measured just after the onset of the eruption on Sunday, September 10th.
• A live-stream video of the eruption is available (here).
• More eruption information is available (here).

    Summit Observations: Summit tilt has remained mildly deflationary over the past 24 hours. Summit seismic activity is dominated by eruptive tremors (a signal associated with fluid movement) with very few volcano-tectonic earthquakes.
    Rift Zone Observations: No unusual activity has been noted along the East Rift Zone or Southwest
Rift Zone; steady rates of ground deformation and seismicity continue along both. Measurements from continuous gas monitoring stations downwind of Puʻuʻōʻō in the middle East Rift Zone—the site of 1983–2018 eruptive activity—remain below detection limits for SO2, indicating that SO2 emissions from Puʻuʻōʻō are negligible.
    Hazard Analysis: Eruptive activity is occurring on the down-dropped block and Halemaʻumaʻu crater, within Kīlauea’s summit caldera and in the closed area of Hawaiʻi Volcanoes National Park. During Kīlauea summit eruptions, the high level of volcanic gases—primarily water vapor (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2)— and fine volcanic particles are the primary hazards of concern, as these hazards can have far-reaching effects downwind.

    As SO2 is released from the summit, it reacts in the atmosphere to create the visible haze known as vog (volcanic smog) that has been observed downwind of Kīlauea. Vog creates the potential for airborne health hazards to residents and visitors, damages agricultural crops and other plants, and affects livestock. For more information on gas hazards at the summit of Kīlauea, please see (this link). Vog information can be found (here).
    Strong winds may waft fine rock particles to areas downwind of erupting vents. People should minimize their exposure to these fine volcanic particles, which can cause skin and eye irritation.  Reports from Hawaiian Volcano Observatory field crews indicate that fine particles of Pele’s Hair and other tephra are being deposited in the area near the Keanakāko‘i Overlook, which is approximately half a mile (about 1 km) from the eruption site. Hawaiʻi Volcanoes National Park has closed the Keanakāko‘i Overlook to the public at this time.
    Other significant hazards also remain around Kīlauea’s summit from Halemaʻumaʻu crater wall instability, ground cracking, and rockfalls that can be enhanced by earthquakes within the area closed to the public. This underscores the extremely hazardous nature of the rim surrounding Halemaʻumaʻu crater, an area that has been closed to the public since early 2008.