A lava dome-like feature formed in the summit crater of Great Sitkin volcano, Alaska, suggesting magma is rising near the surface. As a result, the Alaska Volcano Observatory (AVO) has raised the Aviation Color Code to ORANGE and the Volcano Alert Level to WATCH.
A satellite radar image captured at 05:32 UTC on July 23, 2021, shows a small approximately 50 m (150 feet) diameter area of uplift in the center of the crater at Great Sitkin.
Seismicity has been at relatively low levels this week compared to last week, making AVO suggest that the lava dome-like feature was emplaced last week.
Moderately elevated surface temperatures consistent with this feature were observed in satellite data on July 22. Unfortunately, cloudy conditions have obscured views of the volcano by satellite most of the past week.
AVO said it will continue to closely monitor this new uplift feature, adding that the prognosis for eruptive activity is uncertain.
“Continued growth of the lava dome feature, additional explosive events, or a return to non-eruptive behaviors are all possible.”
The first significant explosion at Great Sitkin since 1974 took place on May 26, 2021. The resulting ash cloud rose up to 4.5 km (15 000 feet) above sea level and drifted east.