SPT and CPT application for liquefaction evaluation in Greece

This research aims to calculate the potential of soil liquefaction due to earthquakes in the coastal area of the gulf of Patras in Greece. For this purpose, the coastal area of the gulf of Patras and its sub-regions, where liquefaction had occurred after an earthquake of M w = 6.4 that struck Greece in 2008, has been selected as the study area. Liquefaction analysis was performed based on geotechnical in-situ tests of standard penetration test (SPT) and cone penetration test (CPT). The results obtained from SPT and CPT were used for the calculation of the safety factor (FS) and the Liquefaction Potential Index (LPI). Then the values of LPI inserted in geographical information systems (GIS) for the production of a liquefaction hazard map, with the Kriging and IDW interpolation methods. The assessment of soil liquefaction was evaluated for three earthquake scenarios: (I) hypothetical earthquake with M w = 7.5 and a max = 0.24 g, (II) hypothetical earthquake with M w = 6.5 and a max = 0.24g, and (III) real earthquake that struck the same area on 8 June 2008 with M w = 6.4 and a max = 0.18 g. Interpretation of liquefaction hazard maps for the three different earthquake scenarios in the research area shows that (a) the first scenario (I) extracted high to very high LPI values in the sub-regions Niforeika-Kato Achaia-Alisos-Vrachneika, (b) the second scenario (II) extracted moderate to high LPI values in the sub-regions Niforeika-Kato Achaia-Alisos and moderate LPI values in the sub-region Vrachneiika, and (c) the third scenario (III) predicted with accuracy some sparse zones where the liquefaction event occurred after the 2008 earthquake. More specifically, it predicted moderate LPI values in the sub-region Vrachneiika, which in general is not prone to liquefaction for this scenario. It may be concluded that the production of preliminary liquefaction hazard maps for different earthquake scenarios, predicts zones where liquefaction may occur after an earthquake event. The most probable scenario in the research area is an earthquake event with M w = 6.5 and a max = 0.24 g (scenario II), which could cause severe damages to the existing buildings and infrastructures.