Recent acceleration of a rock glacier complex, Ádjet, Norway, documented by 62 years of remote sensing observations

Abstract

Recent acceleration of rock glaciers is well recognized in the European Alps, but similar behavior is hardly documented elsewhere. Also, the controlling factors are not fully understood. Here we provide evidence for acceleration of a rock glacier complex in northern Norway, from 62 years of remote sensing data. Average annual horizontal velocity measured by aerial feature tracking increased from ~0.5 myr<Sup>-1</sup> (1954–1977) to ~3.6 myr^-1 (2006–2014). Measured by satellite synthetic aperture radar offset-tracking, averages increased from ~4.9 to ~9.8 myr^-1 (2009–2016) and maximum velocities from ~12 to ~69 myr<sup>-1</sup . Kinematic analysis reveals different spatial-temporal trends in the upper and the lower parts of the rock glacier complex, suggesting progressive detachment of the faster front. We suggest that permafrost warming, topographic controls, and increased water access to deeper permafrost layers and internal shear zones can explain the kinematic behavior.