Deep Vs structure under the city of PATRAS, Greece – Application of the SASW method utilising earthquake recordings at pairs of accelerograph stations

• Published in: Soil dynamics and earthquake engineering (1984) 2023-06, Vol.169, p.107820, Article 107820
• Main Authors: Pelekis, P.C., Batilas, A.V., Athanasopoulos, G.A.
• Format: Article
• Language: English
• Subjects: Deep Vs structure; Surface wave methods; Urban accelerographic network; Vs30
• ISSN: 0267-7261; 1879-341X
• DOI: 10.1016/j.soildyn.2023.107820

Earthquake recordings (vertical component of motion) by the dense urban accelerographs stations of the UPAN network (Patras, Greece) were utilized for estimation of the deep (∼10 km) Vs structure under the city, utilizing the dispersion of surface waves. Multiple pairs of accelerographs of the network were selected (with interstation distances varying from 0.7 km to 6.3 km) that recorded seismic events with epicenters surrounding the city and located on the extrapolation of the straight line defined by the particular pair of accelerographs. The recordings were processed by applying the SASW method and estimating the inverted 1D Vs-depth profiles at the midpoints of the interstation distance. A total of 28 1D Vs-depth profiles were estimated in this way at different locations of the urban area; a deep (∼10 km) 3D model was then derived using a 2D interpolation technique. The resolution of the derived 3D Vs-depth model for shallow depths (∼80 m) was enhanced by embedding a shallow model derived from MASW and ReMi measurements. The new Vs-depth model for the city of Patras (PATRAS-VS) was compared to a number of published Vs models derived for the urban area of Patras and for the broader vicinity of the city. The comparisons indicated an impressive agreement with published models pertaining to the Patras areas, and a general good agreement with models developed for the areas of Rio-Antirrio Straight and the western Corinth Gulf. The new 3D Vs-depth model for the city of Patras developed in the present study is expected to be a useful tool for: (i) retrieving the physical properties of shallow subsurface with adequate resolution, (ii) site characterization and classification as well as for seismic hazard analyses for the Patras area, (iii) mapping the depth to the “seismic” and “geologic” bedrock of the urban area and associated site periods, and (iv) performing seismic response analyses for deep soil profiles. •Surface wave utilization using earthquake recordings by an urban accelerographic network.•Combination of SASW, MASW, and ReMi measurements for generating dispersion curves.•Deep 3-D Vs model for the city of Patras, Greece up to 10 km depth.•Comparison of derived Vs profiles to published related literature.