## 6 Secondary Earthquake Environmental Effects
### Slope Failures
#### 6.1.2 Slope Failures along the Southern Coastal Part of Vathy Bay  
The sites affected by slope failures along the northern regional road of Samos from Vathy town to Avlakia village as well as in the coastal area of Kokkari village (Figures 18 and 20) present similar features in their geology, lithology, active tectonics, and geomorphology and, therefore, they will be presented in the same section. Figure 19: Earthquake-induced slope failures and affected sites in the Potami coastal area (**a**). The area is affected by the active Karlovasi-Kallithea fault, which formed morphological discontinuities (**a**) corresponding to coastal fault scarps on marbles of the Kerketeas unit (**b,c**). (**d**) Unstable marble blocks were detached from the upper parts of the slopes and rolled down to the lower parts of the slope but without affecting the nearby coastal road. Red arrows point to the freshly detached surfaces (**d,e**) and the yellow arrow to the fallen fragments (**e**). Slope failures in this area were generated in the northeastern part of the Mytilinii basin, which is the eastern Neogene basin of Samos [4] (Figures 18 and 20). It is built by formations of the upper series of the Mytilinii basin. In particular, it is composed of lacustrine limestones, traverting, and, in some places, a marly matrix with layers of loose marls, clays, and tufritic bodies with disperse pebbles, while pure conglomeratic breccia are also present in intercalations [4]. These formations are of Pliocene age and their total thickness reaches 250 m.  
The beds of the above formation dip towards the NE with the dip ranging from 10\({}^{\circ}\) to 55\({}^{\circ}\). More specifically, the beds dip towards the NE with 15\({}^{\circ}\) at the Kedros site, 40\({}^{\circ}\) at the Kokkari site, 55\({}^{\circ}\) at the Lemonakia site, 50\({}^{\circ}\) at the Avlakia site, and 30\({}^{\circ}\) at the Tambou beach. It is of importance that at all sites the dip of beds is nearly the same as the dip in the slope, which is a factor that favors the generation of slope failures, especially during strong ground motion such as that caused by the large 2020 earthquake, the epicenter of which is relatively close to the landslide-prone sites. The epicentral distance of these sites ranges from 14 km for the Tsampou beach at minimum to 20 km for Kedros at maximum. From the neotectonic point of view, the area is dissected by NW-SE-striking and NE-dipping normal faults arranged parallel to the shoreline [4; 7]. These faults affect the aforementioned formations and define the almost linear coastline, which has a similar average NW-SE trend. Moreover, they also form high and steep slopes, especially at the Avlakia and Kokkari coastal sites (Figure 20). The 8-km-long, NW-SE-striking and NE-dipping Kokkari-Vathy normal fault dominates the area of the aforementioned slope movements in the southern coastal part of Vathy bay. It defines the southern margin of the structure of Vathy bay. Moreover, it caused tilting of the Pliocene limestones in the area. This tilting constitutes an indication of recent  
Figure 20: Slope failures triggered by the 30 October 2020, Mw = 7.0, Samos earthquake at several sites of the eastern part of the island. (**a–f**) Rockfalls and landslides in the northeastern part of Samos: (**a**) Kedros, (**b**) Kokkari, (**c**) Lemonakia, and (**d–f**) Avlakia. The largest effects were generated at the Avlakia site, resulting in a temporary traffic disruption. Due to reactivation during the aftershock sequence, a barrier made of large concrete blocks was created along the base of the affected slope in order to protect the road and passengers from further slope failures and surface deformation. tectonic activity. Based on the available geological and seismological data, it has been characterized as probably an active fault [7]. The slopes at the Avlakia site, situated almost 100 m from the shoreline, have a height varying from 180 to 200 m and coincide with a steep coastal scarp of a normal fault (Figure 20).