## 4 The Sencelles Bedrock Fault Scarp at the Sta. Eugenia Segment  
Lichenometric analyses of the bedrock fault scarp was carried out at two different sites, both located less than 400 m away from the trench site excavated in the year 2002 [23] and from the Sta. Eugenia Cemetery (Figure 3). A total of 47 thallus measurements were taken, 32 specimens in site 1 (destroyed house site; H in Figure 3) and 15 specimens in site 2 (stone fence site; F in Figure 3) adjacent to the trench site (T in Figure 3). The best-represented lichen species was _Aspicilia calcarea_ with 35 measurements, whilst for _Aspicilia radiosa_ we only identified 13 specimens suitable for measurement. The fault scarp profile displayed in Figure 8 was extracted from the detailed 3D digital terrain model and a topographic map(centimeter scale) performed in the zone by [PERSON] et al. in the year 2001 [20]. The position and relative size of the analyzed thallus of both species, taken on the two analyzed sites, are projected in this profile. The westernmost 840 m of the Sta. Eugenia fault segment features the development of differentially weathered ribbons characterized by the colonization of diverse lichen species and different lichen sizes. Lichen colonization clearly decreases from the top to the base of  
Figure 8: Morphometric and lichenometric features of the bedrock fault scarp at the Sta. Eugenia Fault Segment. (**A**) 3D Digital elevation model (5 cm pixel) of the fault produced by GPS topographic measurements in the zone of the excavated trench in 2002 and Site 1 (Stone Fence; F in Figure 3). (**B**) Synthetic profile of the Sencelles bedrock fault scarp in Site 2 (Destroyed House; H in Figure 3) illustrating the different lichen ribbons analyzed in this paper. Measured Lichen species are plotted to attend to their position in the fault plane, with equivalent sizes (larger or smaller circles). Mean angles of the fault plane bands and ribbons, the position of lichen ribbons above the present ground surface (cm), theoretical width of removed materials by biochemical weathering and mean computed ages (age 2 in Tables 2 and 3) from the obtained LGR functions for the three lower ribbons are displayed. the scrap-free face, which is nearly free of lichens. Considering the intensity of weathering onto the exposed fault plane, two prominent bands, one above the other, are preserved in the near-planar surface of well-cemented calcarenites. These are interpreted as fresh and ancient fault scarps (Figure 8), displaying yellowish and greenish colors, respectively (Figure 4). The basal band displayed a slightly rugged 1.29 m wide surface (fault plane) with a dip angle decreasing from the base to the top of the free face from 87\({}^{\circ}\) to 77\({}^{\circ}\) degrees. This younger band is differentially colonized by the studied lichen species (_A. calcarea_ and _A. radiosa_), with upwards-increasing density and downwards-decreasing size, but arranged in three different ribbons (Figure 8). The basal ribbon B1 (7 cm wide) only presented a few small patches of lichens less than 20 mm in size (Figures 4 and 8). On the contrary, the upper ribbon B3 was densely colonized and lichens coated more than 40 percent of the surface (Figure 4). The intermediate ribbon B2 displayed an intermediate stage of colonization, with less than 25 percent coated by lichens. This intermediate B2 band has been tentatively linked to the 1851 CE Palma earthquake (VII EMS) by previous studies [10,20]. In contrast, the upper band of the scrap showed evidence of long-term exposure produced by earlier fault displacements. This band is very rough, and significantly pockmarked by solution pits. It is colonized by coalescent colonies of _Aspicila_, but mainly of the crustose orange lichen _Xantoria calcicola_ and unidentified _\"foliacea\"_ black lichens. Curiously, this band presented lesser lichen coating (density) than the upper part of the basal band (Figure 4), which can be explained by the exfoliation effect of weathering and flaking of the exposed rocky surface mentioned above [31].