Slope creep in East Iceland observed by satellite radar interferometry

Numerous unconsolidated deposits can be found on slopes in East Iceland that exhibit characteristics of slope movement. While a few of these slopes have been known to be actively? creeping in the past decades, no information has been available about the current activity. In this study I surveyed a large part of East Iceland for possible ongoing slope creep using satellite radar interferomagnetic imaging. A total of 44 radar interferograms were processed using data from the European radar satellites ERS-1, ERS-2, and Envisat, spanning different time-periods during 1993-1999 and 2004-2005. At one site, pofi in Seydisfjordur, ground cracks were discovered in 2000 and GPS measurements in 2001-2002 revealed that these deposits were moving at rates of up to 33 cm/year. No suitable ERS radar data exist from 2001-2002, but interferograms from 1998 and 1999 show up to 10 cm/year displacement-rate in this area, while interferograms from 1995-1997 and 2004-2005 exhibit no signs of displacement. This shows that the pofi deposits started creeping two years before surface cracks were discovered and that the movement is episodic. In search for other active slope displacements in East Iceland I found more than ten locations of previously unknown slope creep. The most prominent displacements were discovered in Vopnafjordur where the deposit creep shows variations in both displacement rate (up to 1 m/year) and areal event during the observation period, which further demonstrates the episodic behavior of unstable slopes in East Iceland.