Seismic velocity model and near‐surface geology at Mycenaean Tiryns, Argive Basin, Peloponnese, Greece

Abstract

A near‐surface seismic refraction tomography survey was completed in the surroundings of the Mycenaean citadel of Tiryns in the Argive Basin, Peloponnese, Greece. The survey encompassed 11 hectares at the Tiryns citadel, an archaeological site listed by the United Nations Educational, Scientific and Cultural Organization as world heritage with over 120 years of excavation history. Site characterization of the shallow subsurface was performed using two‐dimensional seismic refraction tomography of compressional (P) and horizontally polarized shear (SH) wave data along 12 and 9 profiles, respectively. The interpretation of the seismic refraction results is complemented by available archaeological stratigraphy, stratigraphic logs, and new structural data of the exposed bedrock. The tomograms show a transition from unconsolidated fine alluvium at the surface to consolidated clays and silts to hard limestone bedrock. The soil–bedrock boundary dips away from the citadel, influencing the geometry of overlying soils into wedges. Based on twodimensional tomograms of P‐and SH‐wave velocities, the Poisson ratio, shear modulus, Young’s modulus, and bulk modulus were estimated for a four‐layer geotechnical model, which will be used to study seismic site effects. The rock mass quality index of the bedrock at Tiryns is classified as fair to very poor.

Subsurface Geological Characterization of the Late Neogene–Quaternary Argive Basin, Peloponnese, Greece Using Transient Electromagnetic Data and Vintage Stratigraphic Logs

“…The resulting electrical resistivity values ≥300 Ωm for the interpreted bedrock are of basin-scale proportions. The measured narrow low-resistivity range is explained by high porosity levels caused by diagenetic processes, episodes of brittle faulting and fracturing (see Hinojosa-Prieto and Hinzen [25]), a shallow water table (Karastathis et al [23,24]), and highly conductive fluids (brines and leachates) that affect the porous bedrock of sedimentary origin.…”

“…The transition from cohesive (fine-grained) to granular (coarse-grained) Quaternary soils is abrupt (Figure 1). The surface soils of the AB are in angular unconformity with the bedrock (Hinojosa-Prieto and Hinzen [25]). Triassic-Upper Cretaceous strongly-weathered, highly-fractured karstic limestones thrusted against Paleogene flysch deposits during the Alpine orogeny comprise the bedrock (Papastamatiou et al [19]; Tataris et al [20]).…”

“…Although the surficial geology of the AB is well-understood (Papastamatiou et al [19]; Tataris et al [20]), its subsurface geology remains poorly known. Most of the current knowledge comes directly from shallow drill holes (Zangger [21]), a detailed geotechnical engineering soil assessment (Apostolidis and Koutsouveli [22]), and shallow geophysical surveys (i.e., gravity and seismic) within confined areas (Karastathis et al [23,24]; Hinojosa-Prieto and Hinzen [25]; Hinzen et al [26,27].) While this information comes from areas along the coastline and the greater area of Nafplion City, information is scarce for more inland locations.…”

Combined use of refraction seismic, MASW, and ambient noise array measurements to determine the near-surface velocity structure in the Selinunte Archaeological Park, SW Sicily

“…An important step in the modeling of ancient ground motions is the determination of seismic site effects at the time of the earthquake. Hinzen and Weiner (2009), Hinojosa-Prieto and Hinzen (2015), and Hinzen et al (2016) have given examples of site effect evaluation in archaeoseismological context. For further investigations on the potential sources of the two earthquakes that affected Selinunte (Guidoboni et al 2002;Bottari et al 2009) the determination of site effects, which is the purpose if this paper, is an important step.…”