Augustine unrest 2016
Start: February 2016 [1]
Event Type: Not an eruption
Description: From Cameron and others, 2020: "Minor unrest occurred at Augustine Volcano in 2016 in the form of a seismic swarm that began in February and continued intermittently into 2017. This swarm was similar to precursory seismicity observed at Augustine Volcano before previous eruptions, prompting increased surveillance on the Augustine data streams. The unrest did not result in eruption, and the Aviation Color Code and Volcano Alert Level remained GREEN and NORMAL, respectively, throughout the year.
"In 2016, there was a fivefold increase in the number of located earthquakes, totaling 836 for the year. The earthquakes were all located under the summit at shallow depths, 0–3 km (1–2 mi). Following a period of relative quiescence after the 2005–06 eruption, seismicity at Augustine Volcano increased slightly in 2012 when AVO located 54 earthquakes (fig. 8; Herrick and others, 2014). This activity continued to increase in 2013, 2014, and 2015 with 101, 127, and 162 earthquakes, respectively. The Augustine Volcano 2016 earthquake swarm began in February and continued at a high rate through the summer. A decrease in seismicity occurred during the fall and winter. Although the seismic activity looked much like precursory seismicity observed prior to the 1976, 1986, and 2005–06 eruptions, no eruption has yet ensued. No deformation or anomalous gas levels were noted in 2016.
"On January 24, the magnitude 7.1 Iniskin earthquake occurred at 10:30 UTC (1:30 AM AKST), between Augustine and Iliamna Volcanoes, and was the result of tectonic plate motions. This earthquake’s epicenter was about 27 km (17 mi) north of Augustine Volcano and 50 km (31 mi) south of Iliamna Volcano, at a depth of 122 km (76 mi). AVO did not detect any changes at either Augustine or Iliamna Volcano related to the earthquake."
Anomalous seismicity continued in 2017. From Dixon and others (2020): "The number of earthquakes located at Augustine Volcano in 2017 was abnormally high but was less than half (367) the number located in the previous year (836). The high level of seismicity was monitored closely and was determined not indicative of a pending eruption. A gas overflight in April was unable to make measurements of the plume, but on-ground measurements in July indicated that degassing activity remained at low levels. The Aviation Color Code and Volcano Alert Level at Augustine Volcano remained at GREEN and NORMAL, respectively, throughout the year."
"In 2016, there was a fivefold increase in the number of located earthquakes, totaling 836 for the year. The earthquakes were all located under the summit at shallow depths, 0–3 km (1–2 mi). Following a period of relative quiescence after the 2005–06 eruption, seismicity at Augustine Volcano increased slightly in 2012 when AVO located 54 earthquakes (fig. 8; Herrick and others, 2014). This activity continued to increase in 2013, 2014, and 2015 with 101, 127, and 162 earthquakes, respectively. The Augustine Volcano 2016 earthquake swarm began in February and continued at a high rate through the summer. A decrease in seismicity occurred during the fall and winter. Although the seismic activity looked much like precursory seismicity observed prior to the 1976, 1986, and 2005–06 eruptions, no eruption has yet ensued. No deformation or anomalous gas levels were noted in 2016.
"On January 24, the magnitude 7.1 Iniskin earthquake occurred at 10:30 UTC (1:30 AM AKST), between Augustine and Iliamna Volcanoes, and was the result of tectonic plate motions. This earthquake’s epicenter was about 27 km (17 mi) north of Augustine Volcano and 50 km (31 mi) south of Iliamna Volcano, at a depth of 122 km (76 mi). AVO did not detect any changes at either Augustine or Iliamna Volcano related to the earthquake."
Anomalous seismicity continued in 2017. From Dixon and others (2020): "The number of earthquakes located at Augustine Volcano in 2017 was abnormally high but was less than half (367) the number located in the previous year (836). The high level of seismicity was monitored closely and was determined not indicative of a pending eruption. A gas overflight in April was unable to make measurements of the plume, but on-ground measurements in July indicated that degassing activity remained at low levels. The Aviation Color Code and Volcano Alert Level at Augustine Volcano remained at GREEN and NORMAL, respectively, throughout the year."
References Cited
[1] 2016 Volcanic activity in Alaska - Summary of events and response of the Alaska Volcano Observatory, 2020
Cameron, C.E., Dixon, J.P., Waythomas, C.F., Iezzi, A.M., Wallace, K.L., McGimsey, R.G., and Bull, K.F., 2020, 2016 Volcanic activity in Alaska-Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2020-5125, 63 p., https://doi.org/10.3133/sir20205125.
[2] 2017 Volcanic activity in Alaska-Summary of events and response of the Alaska Volcano Observatory, 2020
Dixon, J.P., Cameron, C.E., Iezzi, A.M., Power, J.A., Wallace, K., and Waythomas, C.F., 2020, 2017 Volcanic activity in Alaska-Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2020-5102, 61 p., https://doi.org/10.3133/sir20205102.Complete Eruption References
2016 Volcanic activity in Alaska - Summary of events and response of the Alaska Volcano Observatory, 2020
Cameron, C.E., Dixon, J.P., Waythomas, C.F., Iezzi, A.M., Wallace, K.L., McGimsey, R.G., and Bull, K.F., 2020, 2016 Volcanic activity in Alaska-Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2020-5125, 63 p., https://doi.org/10.3133/sir20205125.
2017 Volcanic activity in Alaska-Summary of events and response of the Alaska Volcano Observatory, 2020
Dixon, J.P., Cameron, C.E., Iezzi, A.M., Power, J.A., Wallace, K., and Waythomas, C.F., 2020, 2017 Volcanic activity in Alaska-Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2020-5102, 61 p., https://doi.org/10.3133/sir20205102.