## 1 Introduction  
In recent decades, aerial photos or satellite optical images have been the most common tools used to generate regional inventories of rock glaciers [1; 2; 3; 4]. Nowadays, the advent of SAR-based satellites and the use of interferometric techniques enable the objective identification of active rock glaciers and quantification of their movement [5; 6; 7; 8]. This is a complementary and powerful tool to improve the reliability of the existing inventories [5]. This work aims to demonstrate the potential of the relatively new Sentinel-1 SAR constellation for this purpose. In particular, Sentinel-1 interferometry is used in the Dry Andes region to obtain a regional inventory of active rock glaciers. Several regional inventories based on optical data [1; 2; 3; 4] can be found for the Dry Andes region. Such inventories have two main limitations. First, the presence of clouds, shadow areas, and snow represents an important constraint for both the completeness and the reliability of the inventory [5]. Second, assessment of the degree of activity in these types of inventories is usually based on geomorphological criteria. This approach is qualitative, subjective, and, as can be seen in the papers of [PERSON] and [PERSON] and in the Master's thesis of [PERSON] [9; 10], has a greater relevance in the discrimination between active rock glaciers and relict rock glaciers than in discerning between active and inactive. These limitations can be partially resolved by the Synthetic Aperture Radar Differential Interferometry (DInSAR) technique, which has been widely used in different regions to identify and quantify movements of these periglacial environment landforms [5; 6; 7; 8]. It provides objective information on the existence of movement, which is one of the main potentialities of the technique. Moreover, the DInSAR technique allows the detection of slow superficial movements that define the limit between active and inactive rock glaciers [9]. In this work, we have considered 2.2 cm/year as a threshold to discriminate between active and non-active rock glaciers. A more detailed classification of landforms as a function of movement rates applied in the Swiss Alps is described in [11]. The phase difference between two backscattered SAR echoes of the same area on the ground taken at slightly different view angles can be used to detect small surface changes in the order of a few centimeters [12]. This technique is known as differential SAR interferometry (DInSAR) and has been shown to successfully detect surface displacements in the radar line-of-sight caused by mass movements in alpine terrain [13]. Some studies on rock glacier deformation suggest that the technique could also be promising for relatively small objects in mountainous terrain [14; 15; 16]. The DInSAR technique has been used previously to detect active rock glaciers in different regions. [PERSON] et al. [5] used SAR interferometry and optical data to map and quantify the movement of 261 rock glaciers in the northern Tien Shan of China. [PERSON] et al. [11] provided a set of recommendations for the use of DInSAR in mountainous areas. They also provided an extensive landform inventory of the western Swiss Alps, including rock glaciers, landslides, and push-moraines. Another example is the work by [PERSON] et al. [17], who used a detailed inventory of landforms related to permafrost (rock glaciers and stable ice-cored moraines) to define the past and present limits in altitude of the alpine permafrost. In this case, DInSAR was used to validate the classification of active landforms by means of geomorphological analysis. In [PERSON] et al. [8], the InSAR technique was used to map 59 rock glaciers in Sierra Nevada, California. Finally, several studies have focused directly on the dynamics of one or several rock- glaciers [12; 15; 18; 19].