Subsidence of the Tolbachik (Kamchatka) Lava Field Constrained by SAR Interferometry

The Tolbachik fissure eruption that emitted more than 0.5 km³ of basaltic lava occurred in the area of the Klyuchevskoy group of volcanoes located in the northern part of the Central Kamchatka depression in the period 27.11.2012-15.09.2013. The lava field includes three lava flows of the total area about 46 km². To estimate the displacements of the surface of the Tolbachik lava fields, a time series of SAR images was processed using the SBAS method of the SARscape software. We collected 35 Sentinel-1A images in the Interferometric Wide Swath mode from the 60D track covering the snowless period of 2017-2019.

Surface of the lava field mostly subsided except small uplifting areas. The amplitude of subsidence was up to 280 mm/year which considerably exceeds our numerical estimates of the thermal subsidence in result of lava cooling. The down-hill flow of the lava viscous inner core and possible post-eruption lava downward retreat within the fissure successfully explains observed residuals.

This study supported by the Megagrant from the Ministry of Science and Education of the Russian Federation under project # 14.W03.31.0033.