Kaʻū News Briefs, Saturday, June 10, 2023

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THIS WEEK'S VOLCANO WATCH article and activity update by U.S. Geological Survey Hawaiian Volcano Observatory scientists and affiliates is headlined Reflections of Recent Eruptions:

  Kīlauea volcano began erupting within Halema‘uma‘u crater at the summit during the early morning of June 7. The eruption marks another in a series of recent eruptions that the Hawaiian Volcano Observatory has been able to successfully forecast!

Lava quickly flooded Halema'uma'u crater floor after the eruption began the morning of June 7, 2023. This photo was taken around 5 a.m., shortly after the eruption started. HVO geologists were in position on the crater rim at Kīlauea volcano's summit, waiting to observe the eruption start. USGS image

    For days to months leading up to all eruptions at Kīlauea since 2018, as well as Mauna Loa in 2022, increased earthquake activity and ground inflation suggested that the magma storage systems below were under stress.
    HVO scientists have noted these periods of “increased unrest,” and they closely monitor the data streams for signals that an eruption may be imminent. In most recent cases, the signs of an imminent eruption become evident only about an hour before the eruption occurs.
    The clearest signals before these recent eruptions are rapidly occurring earthquakes—most not large enough to be felt—as rocks beneath the surface break, along with an increasing rate of inflationary ground motion as pressure builds.
    These signals indicate that magma is creating a pathway towards the surface. Eventually, fountains of lava burst from the ground and a conduit is established; volcanic tremor—a signal indicating fluid movement, like the hum of water moving through a garden hose—begins to replace the earthquakes, slowly becoming the dominant signal. Ground motion then begins to deflate, indicating the release of pressure within the magma system.
    An outlier is the onset of the January 2023 eruption at the summit of Kīlauea. This eruption occurred mere weeks after the previous one had ended in December 2022. Rapid earthquake activity occurred for about 30 minutes, followed by an hour of relative seismic silence before lava broke the surface with eruptive tremor. One hypothesis for why this occurred is the large amount of molten material stored beneath the surface of Halema‘uma‘u crater floor, in combination with the short timeframe following the previous eruption.

Data recorded on June 7, 2023 by five seismometers located in Kīlauea summit region. The data is shown as spectrograms, which display the energy of seismic events (vertical axis) occurring over time (horizontal axis). Distinct earthquake events are the vertical red spikes in the left side of the plots whereas volcanic tremor is the horizontal red band in the right side of the plots. USGS plot

    With close attention to the data on June 7, HVO scientists were able to identify the precursory activity that closely mirrored previous recent eruptions. Kīlauea’s alert level and aviation color code were elevated to WATCH/ORANGE at 3:14 a.m. HST, indicating that an eruption was imminent. HVO field staff were notified and they hurried to the crater rim; just before 4:45 a.m. HST, lava fountains illuminated webcam views and the eruption began. This dynamic activity is confined to Halema‘uma‘u crater within Hawai‘i Volcanoes National Park. If you can’t view it in person, check out the eruption livestream at https://www.youtube.com/usgs/live.
    Volcano Activity Updates: Kīlauea volcano is erupting. Eruptive activity is confined to Halemaʻumaʻu crater within Kīlauea's summit caldera. No unusual activity has been noted along Kīlauea’s East Rift Zone or Southwest Rift Zone.

Tracking SO2 and other Gases from Kilauea Volcano Hawaiian Volcano Observatory scientists use an FTIR to measure volcanic  gas at the Halemaʻumaʻu crater eruption site. The FTIR is aimed at the hot,  glowing lava and the volcanic gas between the lava and the FTIR can be measured. The data is processed to calculate important gas ratios which can give us information about how magma and volatiles are transported in the volcanic plumbing system. For more information on FTIR, see: Volcano Watch  — Infrared (IR) measurements help HVO scientists unravel Kīlauea’s gas chemistry | U.S. Geological Survey (usgs.gov).

     Halemaʻumaʻu Lava Lake Observations: Multiple minor fountains remain active on the western Halema‘uma‘u crater floor and the vent on the southwest wall of the caldera continues to feed lava onto the westernmost part of the crater floor. Lava fountain heights have decreased since the eruption onset, but remain up to about 9 meters (30 feet) high. Active lava and vents cover much of the west half of Halemaʻumaʻu crater in a broad horseshoe around a central uplifted area. An active lava lake is centered within the uplifted area and is fed by a vent in its northeast corner. This feature is the "western lava lake" from prior eruptions that has been reactivated along with a smaller circular pool just southeast of the lake. A much smaller area of lava also remained active in the eastern portion of the crater floor overnight. A live-stream video of the crater is available at https://www.youtube.com/usgs/live.
    Summit Observations: Summit tilt has remained deflationary over the past 24 hours. Summit seismic activity is dominated by eruptive tremor (a signal associated with fluid movement). Volcanic gas emissions in the eruption area are elevated; a sulfur dioxide (SO2) emission rate of approximately 11,000 tonnes per day was measured yesterday, June 9, 2023.
    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 in the middle East Rift Zone—the site of 1983–2018 eruptive activity—remain below detection limits for SO2.

A helicopter overflight on June 8, 2023, allowed for aerial visual and thermal  imagery to be collected of Halema‘uma‘u crater at the summit of Kīlauea.  The eruptive activity has consisted of lava fountaining and lava lake  activity, confined within the crater. The scale of the thermal map ranges  from blue to red, with blue colors indicative of cooler temperatures and  red colors indicative of warmer temperatures. USGS image

    Hazard Analysis: The eruption at Kīlauea’s summit is occurring within a closed area of Hawai'i Volcanoes National Park. High levels of volcanic gas—primarily water vapor (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2)—are the primary hazard of concern, as this hazard can have far-reaching effects down-wind. As SO2 is continuously released from the summit during the eruption, it will react in the atmosphere to create the visible haze known as vog (volcanic smog) downwind of Kīlauea. Vog information can be found at https://vog.ivhhn.org/. 
    Additional hazards include Pele's hair and other lightweight volcanic glass fragments from the lava fountains that will fall downwind of the fissure vents and dust the ground within a few hundred meters (yards) of the vent (s). Strong winds may waft lighter particles to greater distances. Residents and visitors should minimize exposure to these volcanic particles, which can cause skin and eye irritation. 
    Other significant hazards also remain around Kīlauea caldera 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 Kīlauea caldera rim surrounding Halemaʻumaʻu crater, an area that has been closed to the public since late 2007. 

    Mauna Loa is not erupting. Its USGS Volcano Alert Level is at NORMAL. Webcams show no signs of activity on Mauna Loa. Seismicity remains low. Summit ground deformation rates show inflation above background levels, but this is not uncommon following eruptions. SO2 emission rates are at background levels.
    There were four earthquakes with 3 or more felt reports in the Hawaiian Islands during the week ending on Thursday: a M3.3 earthquake 5 km (3 mi) WSW of Volcano at 0 km (0 mi) depth on June 7 at 4:43 a.m. HST, a M3.4 earthquake 4 km (2 mi) SW of Volcano at 1 km (0 mi) depth on June 7 at 2:35 a.m. HST, a M2.6 earthquake 2 km (1 mi) SSE of Volcano at 1 km (0 mi) depth on June 3 at 12:36 p.m. HST, and a M3.0 earthquake 13 km (8 mi) S of Volcano at 6 km (4 mi) depth on June 2 at 10:15 a.m. HST.
    HVO continues to closely monitor Kīlauea and Mauna Loa. Visit HVO’s website for past Volcano Watch articles, Kīlauea and Mauna Loa updates, volcano photos, maps, recent earthquake information, and more. Email questions to askHVO@usgs.gov.