## 3 Results  
### SAR Observations  
The results obtained by analyzing the descending orbit SAR images show the details of the emerging craters and migrating crater chains. The sequence of the georeferenced descending SAR amplitude images is presented in Figure 4.  
Prior to the 2021 eruption, the data allowed to locate an old (Holocene) eruption crater open to the NW. Day 1 of the eruption was 19 September 2021, where a localized eruption vent appeared at the northern flank of this crater. On Day 7 of the eruption (25 September 2021), the presence of new craters could still not be identified in our SAR amplitude images, although the presence of an extensive cone was evident by a moderate and smooth appearance implying predominantly fine-grained tephra deposits (Figure 4a). SAR amplitude images imply that the initial eruption was fed from a single point-like vent and was not associated with a buildup of large craters or fissures. On Day 11 of the eruption (29 September 2021), the SAR image showed five new craters (Figure 4b). Four were in the NW part of a newly evolving cone and one on the SE flank at the southern rim of the pre-existing Holocene crater. In this image, the craters of the main cone are very well-defined by the bright (high reflectivity) upper rim of the crater walls, while the deepest parts and one of the inner crater walls are shown in shadow (low reflectivity). Onthe other side, the southeastern crater has only one visible brighter rim, but its location can be confirmed by the intensity profile and in the optical images. Furthermore, it can be seen in the SAR amplitude images that the location of the new craters is almost perfectly linear, and the shape of the craters is round (Figure 4b). In the following SAR images, linearity is still observed, but the number of craters varies. First, fewer craters are visible, which may be attributed to intense coverage and obscuration by tephra fall. On Day 23 (11 October 2021), the SAR image shows that a new open crater evolved on the NW continuation of the crater row associated with a crater wall collapse. In addition, other craters formed both to the NW and SE of the main cone (Figure 4f). Likewise, the volcanic edifice appeared more circular (in map view) after 11 October (day 23 of the eruption). Until Day 27 (15 October 2021), the craters maintained a circular outline and were NW-SE aligned; thus, they evolved following a stable linear trend for approximately 20 days (Figure 4g). On Day 39 of the eruption (27 October 2021), we see that new craters began to develop in the SE, where two new parallel craters emerge (Figure 4h). This generates two concentrations of craters: a linear one to the NW and a more disaggregated one in the SE sector of this structure. On Day 43 of the eruption (31 October 2021), we observe the appearance of a new crater between the concentration of craters in the NW and the SE (Figure 4i). In the subsequent two weeks (captured by SAR images on 3, 4, and 12 November 2021), we see a small variation in the number of visible craters while they maintained their linear distribution to the NW and were more disaggregated to the SE. On Day 71 (28 November 2021), we observe an outbreak of craters on the northern flank and in the southern part of the volcanic edifice (Figure 4m). This date is associated with major structural changes, as we observed the appearance of other craters, some only half visible in a crescent form, which are located mostly on the NW and SE flanks of the cone. This change from a linear crater evolution to a more distributed cluster continues afterward, especially in the last phase of the eruption, which was declared over on Day 85 (13 December 2021). Looking at the general distribution of the craters seen in the SAR amplitude images, we can visualize three phases: The first one (Phase 1), lasting from the beginning of the eruption until 15 October 2021 (day 27 of the eruption), is expressed by a clear alignment of all craters (Figure 4a-g).