August 24, 2021: Kilauea Volcano stirs.
August 30, 2021: Volcanologists get technical (note: this video is over an hour long. Here is some background.)
September 2, 2021: Per the Hawaiian Volcano Observatory:
Based on the above sequence of events the U.S. Geological Survey’s Hawaiian Volcano Observatory (HVO) issued a Volcano Observatory Notification for Aviation (VONA) and Volcano Activity Notice (VAN) on August 24, changing the aviation color code and volcano alert-level from Yellow/Advisory to Orange/Watch. Was the volcano going to erupt? Symptomatically, all the signs consistent with magma movement were observed, including increased seismicity and ground deformation. We took a “wait and see” approach, while we continued to closely monitor the situation. All the geologists were primed to go to the field at a moment’s notice!
Over the next 36 hours, the earthquake counts diminished, and tilt rates decreased—implying that an eruption was less likely. Based on the observed decline in activity, HVO issued a second VONA and VAN on August 26, changing the status of the volcano from Orange/Watch back to Yellow/Advisory. Making the call on whether or not a volcano is going to erupt is not easy, and Pele still seemed primed for action.
Subsequently, on the evening of August 26, at 6:00 p.m., tilt west of the caldera ramped up, and was followed by an increase in seismicity at 8:30 p.m. The increase in earthquakes and in deformation suggested the intrusion was still being supplied with magma. Characteristically, all the elements that contribute to an eruption were present. But notably, seismicity remained at deeper levels within the volcano, and movement of magma toward the surface was not detected.
How do we as volcanologists deal with the uncertainties of whether or not the volcano will erupt? One way is to look at past eruptive behavior. Last week’s Volcano Watch reviewed examples of past volcanic activity. Intrusions happened in the 1960s, 1970s, early 1980s, and more recently in 2006 and 2015. The only time an eruption occurred, following the many intrusions, was in 1974.
All the events of the past week had volcanologists on high alert, ready to respond as our data indicated magma was on the move. Was the volcano going to erupt? We had no idea how the story would end. We are only able to closely monitor the situation, and watch as things unfold. This time we observed an intrusion. For residents, visitors, and geologists hoping to see red rock, the intrusion was a failed eruption.
Featured image: View through webcam on August 25, 2021.