GEOPHYSICAL INVESTIGATIONS OF TERRESTRIAL TSUNAMI DEPOSITS AT CAESAREA MARITIMA, ISRAEL

A growing body of geoarchaeological evidence indicates the eastern Mediterranean has experienced destructive tsunamis in the past, and is at risk from similar disasters in the future. Historical records suggest between the Roman and Early Islamic periods at least five major tsunamis impacted the eastern Mediterranean coast. Tsunamis have been strongly implicated in the degradation and eventual submergence of a Roman megaharbor - Caesarea Maritima - on the north-central Israeli coast, where distinctive sedimentary packages indicative of tsunami activity have been identified through archaeological and geological research. These sediments constitute the first geological corroboration of numerous tsunami accounts in the Mediterranean historical record. The majority of these studies have been performed offshore; terrestrial counterparts have been interpreted through the review of previous archaeological reports, as many of the primary coastal areas have been excavated to the earliest periods and the overlying sediments removed. Therefore, in situ tsunami deposits on land are poorly documented.

Our 2018 fieldwork sought to advance current understanding of the spatial distribution, architecture, and stratigraphic relationships of sedimentary units as related to tsunami events at Caesarea Maritima. The team employed ground-penetrating radar (GPR) and frequency domain electromagnetic (FDEM) techniques to elucidate the subsurface architecture. GPR has increasingly become a favored tool in research on past tsunami activity, due to its capacity for visualization of deposits both in terms of internal structure and lateral extent. FDEM is a useful complement to GPR, providing rapid characterization of sediment composition over a landscape, and allowing for differentiation between types of sedimentary deposits. During our field campaign, we generated GPR and FDEM profiles for coastal areas to the north, south, and inland of Caesarea, targeting areas with high potential for preservation of tsunami deposits such as the Herodian hippodrome and agricultural plots. Here we present initial interpretations of the geophysical data, and integrate the results with the previously conducted research to improve understanding of potential tsunami inundation history and deposit preservation in archaeological contexts.