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Sulfur Dioxide Emission Rates Below Detection Limits

December 5, 2018, 11:17 AM HST (Updated December 5, 2018, 11:17 AM)
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The U.S. Geological Survey released the Hawai‘i Volcano Observatory Weekly Update on Tuesday, Dec. 4, 2018.

This photo shows the widest portion of the Fissure 8 channel, at roughly 425 meters across. Click to enlarge. PC: USGS

Kīlauea Volcano is not erupting. Rates of seismicity, deformation, and gas release have not changed significantly over the past week. Deformation signals are consistent with refilling of the middle East Rift Zone.

Observations: HVO monitoring during the past week shows low rates of seismicity at the summit and East Rift Zone (ERZ). Earthquakes continue to occur primarily at Kīlauea’s summit and south flank areas.

In the ERZ, tiltmeters reveal little change over the last week, with GPS indicating some inflation downrift from Puʻu ʻŌʻō. At the summit, tiltmeters recorded a small DI (deflation-inflation) sequence over the weekend; the current trend is minor deflation.

Sulfur dioxide emission rates have been below detection limits in the LERZ since early September, though minor amounts of volcanic gas are still present. Last week, sulfur dioxide emission rates measured ~35 t/d at the summit as well as ~35 t/d in the ERZ. These most recent measurements are consistent with the extremely low emissions from Kīlauea over the past few months.

Sept. 4 was the last time active lava was observed along the LERZ; Dec. 5 will mark three months with no eruptive activity at the surface. According to the Smithsonian Institution’s Global Volcanism Program, volcanoes with no eruptive activity over a three-month period are no longer classified as having a “continuing” eruption. Based on this Global Volcanism Program criterion, the LERZ eruption could be considered to be over. However, there is one known example (Mauna Ulu, 1969-74) in which Kīlauea’s rift zone activity resumed after more than three months had passed. Although this phase of Kīlauea’s activity has now reached this three-month threshold, it is important to note that it is still an active volcano that could erupt in the near future and associated hazards have not changed. Magma is being supplied to Kīlauea and geophysical datasets continue to show evidence for movement of material through the magma system, including the refilling of the ERZ.

Hazards are still present in the LERZ eruption area and at the Kīlauea summit. Residents and visitors near recently active fissures and lava flows should stay informed, heed Hawai‘i County Civil Defense and National Park warnings, and be prepared, if necessary, to self-evacuate in the unlikely event of renewed activity. Note that Hawai‘i County maintains a closure of the entire flow field and the vents and prohibits access to the area unless authorized through Civil Defense.

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The Hawaiian Volcano Observatory (HVO) continues to closely monitor Kīlauea’s seismicity, deformation, and gas emissions for any sign of reactivation, and maintains visual surveillance of the summit and the East Rift Zone. HVO will continue to issue a weekly update (every Tuesday) and additional messages as warranted by changing activity.

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