## 7 Secondary Environmental Effects Induced by the 1953 Ionian Sea Earthquakes
### Secondary Effects Induced by the 12 August 1953 Ionian Sea Earthquake in Cephalonia Island
#### 7.3.8 Effects on Vegetation  
In the aforementioned area of Markopoulo village (Figure 11), effects on vegetation were also observed [20]. The root systems of shrubs and trees were destroyed, resulting in their drying. Environmental Effects Induced by the 12 August 1953 Ionian Sea Earthquake on the Ithaki and Zakynthos Islands  
In Ithaki Island, the earthquake-induced effects included slope failures, tsunami and ground cracks (Figure 11; TAXYDROMOS, 13.08.1953, 16.08.1953; TA NEA, 13.08.1953; NEOLOGS PATRON, 13.08.1953; PELOPONNIOSOS, 13.08.1953; EMPROS, 14.08.1953; ELEFTHERIA, 15.08.1953; I MERA, 16.08.1953). The 12 August 1953 earthquake triggered slope failures in coastal areas of Ithaki Island (Figure 11; TAXYDROMOS, 16.08.1953; NEOLOGS PATRON, 13.08.1953; TA NEA, 13.08.1953; I I MERA, 16.08.1953). The slope failures were mainly comprised of rockfalls and slides. The volume of the mobilized material was so large, in some sites, that their morphology was altered. In particular, several coasts at the base of affected slopes disappeared under large volumes of mobilized materials (TA NEA, 13.08.1953). Slope failures were triggered along high and abrupt coastal slopes. In some sites, the mobilized material created dust clouds and fell into the sea resulting in local roughness (NEOLOGS PATRON, 13.08.1953). The synergy of the dust clouds and the sea roughness gave the impression that large areas were submerged (NEOLOGS PATRON, 13.08.1953). Further information on the exact location of these effects and the volume of the mobilized material were not available in the studied sources. Moreover, failures were generated along slopes over Frikes, Lefki and Ayios Ioannis villages (Figure 11; I IMERA, 16.08.1953). The mobilized material accumulated on the adjacent roads and contributed to the complete destruction of heavily affected buildings within the villages (I IMERA, 16.08.1953). The earthquake triggered tsunami, which affected mainly Vathi in Ithaki Island (Figure 11; EMPROS, 13.08.1953; TAXYDROMOS, 13.08.1953; TA NEA, 13.08.1953; NEOLOGS PATRON, 14.08.1953). The waves inundated the coast and moved further inland, up to the squares of Vathi (NEOLOGS PATRON, 14.08.1953). Water marks of small seaweed pieces were left on streets of the town, indicating the extended inundation of the coastal area (TA NEA, 13.08.1953). Some people, found along its course were swept away, but no casualties were reported (NEOLOGS PATRON, 14.08.1953). Ground cracks formed in several sites of the road network in Ithaki Island (Figure 11; TAXYDROMOS, 16.08.1953; NEOLOGS PATRON, 13.08.1953, 14.08.1953; EMPROS, 14.08.1953; I IIMERA, 16.08.1953). In particular, they were observed along the road connecting Vathi with the rest of the island (NEOLOGS PATRON, 13.08.1953) and, more specifically, leading from Vathi to Stavros (EMPROS, 14.08.1953). They were also formed along the pier in Vathi (ELEFITHERIA, 15.08.1953). They were also observed in several sites of northern Ithaki. The 12 August 1953 triggered environmental effects in Ithaki and Zakynthos Islands (Figures 11 and 12) located northeast and south of the most earthquake-affected Cephalonia respectively. Such effects were not observed in Lefkada, located north of Cephalonia. In Zakynthos, the 12 August 1953 induced secondary environmental effects including ground cracks, subsidence, lateral spreading and liquefaction phenomena, hydrological anomalies, slope failures and hydrocarbon-related phenomena (Figure 12). Ground cracks were observed in several sites of Zakynthos town (Figure 12). Its coastal part was intensively deformed by ground cracks, subsidence up to half meter in several sites and submarine landslides resulting in changes in seabed morphology and variation in depth (NEOLOGS PATRON, 13.08.1953 14.08.1953; I MERA, 13.08.1953, 14.08.1953; PELOPONNIOS, 16.08.1953; TAXYDROMOS, 16.08.1953). Ground cracks were also observed in sites affected by slope failures, for example in Kokkinos Vrachos (Red Cliff in English) site (Figure 12).