V021-0019
Subsidence of the Tolbachik (Kamchatka) Lava Field Constrained by SAR Interferometry

Thursday, 10 December 2020
Poster
Valentine O Mikhailov1, Elena P. Timoshkina1, Maria S. Volkova1, Nikolai M Shapiro2,3 and Pavel N. Dmitriev1, (1)Schmidt Institute of Physics of the Earth RAS, Moscow, Russia, (2)Institut des Sciences de la Terre, Université Grenoble Alpes, CNRS (UMR5275), Grenoble, France, (3)Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia
Abstract:
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.

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