The Nature of Deformations of the Western Slope of Shiveluch Volcano after the Eruption on April 11, 2023, Identified by SAR Interferometry

Abstract

Using the images of the Sentinel-1A satellite, taken from May 1 to September 22, 2023, and the differential interferometry method (DInSAR) we calculated successive displacement fields in time, which clearly show a dome-shaped uplift on the western slope of Shiveluch volcano, 8‒8.5 km west of its active crater. The uplift grew especially intensely at the satellite acquisition intervals of May 1‒13, 2023; May 13‒25, 2023; and May 25‒June 6, 2023. To confirm the hypothesis on the formation of the displacement region due to magma intrusion beneath the western slope of the volcano, numerical modeling was carried out and the parameters of the sill-like magma body, which forms the displacements on the surface that best match the displacement observed from satellite radar interferometry data, were determined. It is assumed that, after the eruption on April 11, 2023, magma rose from a depth of 20‒25 km through a fissure formed under the western slope of the volcano and intruded horizontally beneath the slope at a depth of 1‒2 km in the north-northwesterly direction. Within the precision of data on slope displacements, the size of the magma body varies from 6.0 × 3.0 km at 1 km depth to 5.25 × 1.4 km at 2 km depth, while its height ranges from 0.5 to 1.75 m and its volume, from 0.009 to 0.0129 km³. Thus, based on radar interferometry data together with the data on the distribution of seismic activity accompanying the movement of magma, the model of the magma body that intruded beneath the western slope of Shiveluch volcano in the postparoxysmal phase of the eruption on April 11, 2023, was constructed. The formation of a new extrusive dome on the western slope of Shiveluch volcano at the end of April 2024 confirms the hypothesis about the intrusion of magmatic material beneath the western slope of the volcano and allows estimating the rate of magma rise to the surface.