Geomorphological mapping and lithological heterogeneity as tools for the assessment of liquefaction likelihood: Piniada Valley case study (central Greece)

Assessment of liquefaction susceptibility of Holocene sediments in alluvial plains is one of the first step for regional planning, hazard mitigation, and land use management in seismically active regions. Subtle geomorphological features resulting from recent depositional processes can significantly improve mapping liquefaction likelihood since they also express the lithology and distribution of Holocene sediments. Widespread liquefaction phenomena were triggered by the 2021 Mw 6.,3, Damasi, Larisa earthquake over Piniada Valley (Ganas, et al., 2021; Papathanassiou, et al., 2022), a narrow section of Pinios river course in central Thessaly (Figure 1). As we compiled a detailed geomorphological/geological map for the purposes of this investigation and correlated it to the spatial distribution of the earthquake-induced liquefaction phenomena, we observed that liquefaction surface occurrences (ejecta, craters. ground fissures, lateral spreading) are highly correlated to point bars and abandoned river channels formed during the last century. Both geomorphological units consist of mainly sand, with the common occurrence of a thin clayey cap layer if abandoned.