Description: From Orr and others, 2023: "In 2019, Pavlof Volcano showed signs of weak activity that caused AVO to raise the Aviation Color Code and Volcano Alert Level to YELLOW and ADVISORY three times...The first change was made on May 15, 2019, in response to an increase in seismic tremor and webcam images of robust summit degassing. The Aviation Color Code and Volcano Alert Level were lowered back to GREEN and NORMAL on June 12, after activity declined...
"A total of 90 earthquakes were located within 20 km of Pavlof Volcano during 2019. Of these events, 44 were classified as volcano-tectonic (VT) earthquakes, with a collective depth range of −2.85 to 31.5 km and a local magnitude (ML) range of −0.41 to 1.65. The other 46 were classified as LP earthquakes, with a depth range of 8 to 34 km and a ML range of −0.36 to 1.65. Of the 46 LP events, 21 were located ~5 km northeast of Pavlof Volcano beneath Pavlof Sister, a pattern also seen in the seismicity of previous years (Power and others, 2004b). AVO recorded several tremor episodes at Pavlof Volcano in 2019. There is no obvious temporal relationship between the tremor and the earthquake activity...The activity in 2019 started with weak, intermittent tremor on May 15-19. Two brief tremor signals (~3 minutes each) were then observed on May 29, followed by several brief tremor bursts on May 31...
"The annual number of earthquakes located at Pavlof Volcano increased between 2017 and 2019. This trend is probably influenced by improvements made to Pavlof Volcano’s seismic network in the summer of 2017, but the fact that AVO located significantly fewer events in 2019 than 2018 suggests a change in activity level unrelated to the network improvements."