Geology seismotectonics and soil liquefaction susceptibility of Ilgın (west-central part of Turkey) residential area

In this study, soil liquefaction susceptibility of the Ilgın residential area, that is located in the first-degree earthquake zone in the central part of Turkey, was investigated. Safety factors of soil liquefaction were calculated by using standard penetration test (SPT) blow counts, which are determined in different levels of 45 boreholes, measured groundwater level data and fines content (FC) of soil which is determined through laboratory tests. Soil liquefaction safety factors were calculated by using earthquake magnitude (ML=6) and different earthquake peak lateral ground accelerations (PGA) such as 0.1, 0.2, 0.3 and 0.4 g. In the soil, up to 12 m depth, if liquefaction is likely to occur for 0.1, 0.2, 0.3 or 0.4 g of earthquake lateral peak ground acceleration, soil liquefaction susceptibility is classified as “very high”, “high”, “medium” or “low”, respectively. If liquefaction does not occur in the soil for 0.4 g of PGA, then soil liquefaction susceptibility is classified as “very low” or “non-liquefiable soil”. Based on this classification, soil liquefaction susceptibility maps of Ilgın residential area are prepared for depths of 2, 4, 6, 8, 10 and 12 m. The cumulative liquefaction susceptibility ratio of soil (the number of analyses is determined/the total number of analyses) below the groundwater table is determined to be 63%, 87%, 80%, 80%, 64% and 56% for depths of 2, 4, 6, 8, 10 and 12 m, respectively. Significant liquefaction can be expected in the soils having the same characteristics in the Ilgın residential area and its surroundings in case of an earthquake with magnitude of 6-6.5. Much property may happen in case of an earthquake as a result of this soil liquefaction. Therefore, precautions must be taken in order to prevent losses in Ilgın and its vicinity.