Evolution of the 2021 lava dome at Great Sitkin Volcano, Aleutian Islands - analyzed by multi-sensor remote sensing data

Integration of remote sensing datasets provides critical information for monitoring, hazard assessment, and scientific investigation of eruptions at remote volcanoes. The 2021 eruption of Great Sitkin offers an ideal test case for multi-sensor analysis of effusive and explosive activity that has impacted regional aviation and threatened nearby communities. After an initial vulcanian eruption on May 25, 2021, a new lava dome began growing in the center of the crater of Great Sitkin Volcano in the central Aleutian Islands sometime between July 14 and 22, 2021. In order to study the spatio-temporal evolution of this newly formed lava dome, we have been jointly analyzing multi-sensor remote sensing (thermal, optical and radar sensor) data of different spatial and temporal resolution. The new lava dome was first detected on July 22, 2021 using weather-independent very high spatial resolution (VHR) synthetic aperture radar (SAR) imagery of the TerraSAR-X mission. Maxar VHR optical imagery in the following days showed rapid growth of the lava dome compared to the initial TerraSAR-X imagery. Observations from VHR optical and SAR data have been analyzed to track dome morphology (diameter, height, flow textures) at low temporal resolution (days). In order to get a denser time series, multi-sensor thermal imagery (MODIS/VIIRS/Sentinel-3) with several observations per day have been analyzed to study the evolution of the lava dome and estimate its volumetric change. Based on the most recent observations (August 3, 2021) the lava dome had a diameter of about 180 m and an estimated total volume of ~10^6 m³. The time series of lava dome dimensions is modeled to invert for lava rheology and compared to geochemical and geophysical datasets for assessment of eruption evolution and hazard.