Overview of the seismic unrest in early March 2023 at Tanaga Island, which includes Takawangha and Tanaga volcanoes. The seismic data highlights the timing and amplitude of the largest earthquakes in the sequence. Thousands of earthquakes occurred during the time shown in the figure, but most were small and are not visible at the scale of the figure. Elevated earthquake activity under the volcanoes began in the fall of 2022 but increased dramatically on 8 March 2023. Earthquake locations during the swarm migrated from beneath Takawangha to beneath Tanaga and shallowed, increasing the likelihood that the activity could lead to an eruption and prompting AVO to increase the Aviation Color Code/Alert Level to ORANGE/WATCH. Earthquake rate and magnitude remained elevated through 12 March 2023 and then began to decline slowly. No signs of unrest were detected in other data streams. The decline in earthquake activity and lack of additional signs of unrest decreased the potential for an eruption so AVO lowered the Aviation Color Code/Alert Level to YELLOW/ADVISORY on 16 March.
Volcano(es): Takawangha Tanaga
Photographer: Lyons, John
URL: avo.alaska.edu/image/view/194165
Tanaga unrest 2023
On Tuesday, March, 7, 2023, AVO elevated the Aviation Color Code and Volcano Alert Level at Tanaga to YELLOW/ADVISORY, stating "earthquake activity beneath Tanaga Volcano began to increase slowly starting at about 1:30 pm AKST today. At roughly 8:45 pm AKST this evening, the activity escalated with earthquakes occurring as often as 2 or 3 each minute. Initial locations of these earthquakes place them at shallow depths beneath the summit of Tanaga Volcano, and the largest of these earthquakes have magnitudes between 2 and 3."
On Thursday, March 9, 2023, AVO elevated Tanaga again to ORANGE/WATCH, stating "Over the past 24 hours, earthquake activity near Tanaga Volcano has been elevated and continues. This sustained activity indicates an increased potential for eruption at the volcano.*** Seismic activity is also elevated at Takawangha volcano, which is about 8 km (5 mi) east of Tanaga on Tanaga Island. If an eruption were to occur, it is uncertain at this stage if it would come from Tanaga or Takawangha."
Please cite the photographer and the Alaska Volcano Observatory / U.S. Geological Survey when using this image.
Full Resolution.