Ground liquefaction has been reported to occur for shallow earthquakes with a moment magnitude greater than 4.6. The first author of this study has collected many boiled soil samples from various liquefied since 1992. This study is concerned with the grain size distribution, physical and the shear strength properties, permeability/hydraulic conductivity of liquefied granular soils, relative density through laboratory tests and some interrelations are explored. It is shown that every granular geo-material may liquefy if the necessary conditions are satisfied. Large earthquakes may cause even the liquefaction of silty/clayey and/or gravelly soils. Empirical methods purely based on SPT values or its CPT /Vs varieties are not appropriate while the method proposed by Aydan-Kumsar is more appropriate as it can count the most fundamental parameters such as permeability and shear strength of various grounds. If the samples are subjected to pressure under confined state, it is possible to evaluate the characteristics of soils prone to liquefaction at any depth.

During the last decades, liquefaction damages induced by earthquakes have underlined the importance of identifying effective soil improvement techniques for mitigation purposes. Vibratory methods, such as rammed aggregate piers, are commonly used to densify sands and silty sands, erroneously neglecting the influence of the lateral stress. This paper presents the results of a series of liquefaction mitigation case studies carried out using rammed aggregate piers in Christchurch (New Zealand), Boca de Briceno (Ecuador), and Bondeno (Italy) following the 2010-2011 Canterbury seismic sequence, the 2016 Muisne earthquake, and the 2012 Emilia seismic sequence, respectively. The availability of coupled piezocone and seismic dilatometer tests before and after treatment enabled a geotechnical characterization of the three sandy sites to be made, along with estimating the at-rest lateral earth pressure coefficient, and comparing the effectiveness of the treatment at the trial sites. Finally, the paper proposes an updated procedure for liquefaction assessment that takes into account both the increase in soil density and lateral stress produced by ground improvement.

On February 6th 2023 two major earthquakes struck southeast Turkey, M7.7 Kahramanmaras and M7.6 Elbistan, respectively. Unfortunately, due to the impact of these catastrophic events more than 50 000 casualties and 35 000 collapsed buildings have been reported since then. The aim of the study is to demonstrate preliminary site response analysis and assessment of re -liquefaction potential of sites which have been affected by the earthquakes - especially the cities of Iskenderun and Golbasi. Both site -specific areas have clear evidences of liquefaction and lateral spreading events which imply the focus of the presented paper. A series of geophysical MASW and microtremor tests have been performed in order to determine shear wave velocities up to depth of 30 m as well as the fundamental natural frequency of the soil deposits. Moreover, samples have been collected from sand and silt ejecta in order to evaluate some basic physical properties - grain -size curves, specific gravity and plasticity parameters. On the basis of the obtained data seismic classification of the investigated sites according to current design codes has been made and in-depth distance to relatively stiff layer has been assumed. For the sake of evaluating risk of re -liquefaction the widely -used simplified stress -based approach to triggering assessment has been adopted considering some rules of the thumb (e.g., sieve analysis and plasticity properties evaluation). Lastly, post -liquefaction reconsolidation settlement and lateral displacement have been determined in terms of future earthquakes.