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Significant and widespread liquefaction occurred in İskenderun during the 2023 moment magnitude (Mw) 7.8 Kahramanmaraş earthquake. Liquefaction effects on buildings were observed in several areas of İskenderun, predominantly in areas of reclaimed land and near historic shorelines. Liquefaction-induced building settlements were particularly concentrated in the Çay District, which is almost entirely reclaimed land. Liquefaction-induced ground and building settlements were either marginal or not apparent in areas away from the historical shorelines. Building settlement and ground deformation were documented at 26 buildings in İskenderun through lidar scans and laser-level hand measurements. Liquefaction-induced building settlements ranged from 0 to 740 mm. Building-ground interactions were evident from hogging ground deformations, including cases where buildings deformed nearby ground and damaged nearby buildings, and sagging buildings. Historic land development affected the spatial extent of observed liquefaction-induced building damage. Representative liquefaction-induced building settlement and building interaction case histories are discussed and key insights are shared. [ABSTRACT FROM AUTHOR]

Tools for characterizing thin layering and groundwater table conditions are evaluated at silty soil sites being assessed for liquefaction. Thin interlayered stratigraphy and groundwater table fluctuation are two potential causes for inconsistencies observed during the Canterbury earthquake sequence, wherein liquefaction did not manifest at several silty soil sites, despite simplified liquefaction assessment procedures indicating severe manifestations would be expected. Site investigations should capture these features to allow for improved assessment of liquefaction potential at silty soil sites. Cone penetration tests (CPTs), mini-CPTs, and sonic borings do not adequately capture thin layering. However, detailed logging of high-quality samples captures the actual in situ layering that may help explain the limitations of simplified liquefaction assessment procedures at these sites, revealing the need to understand underlying limitations in current site investigation techniques. Piezometers, sonic borings, high-quality sampling, crosshole testing, and regional groundwater maps are evaluated to assess their ability to capture complex groundwater conditions. Multiple groundwater measurement methods are typically required to characterize groundwater fluctuations. An approach to using enhanced site characterization tools is recommended for liquefaction assessments at silty soil sites with thin layering and groundwater fluctuations. Key words: site characterization, thin layering, silty soils, groundwater, liquefaction. Les outils de caracterisation des couches minces et de l'etat de la nappe phreatique sont evalues sur des sites de sols limoneux en cours d'evaluation pour la liquefaction. La stratigraphie a couches minces intercalees et la fluctuation de la nappe phreatique sont deux causes possibles d'incoherences observees pendant la sequence du seisme de Canterbury, ou la liquefaction ne s'est pas manifestee sur plusieurs sites de sols limoneux, malgre des procedures simplifiees d'evaluation de liquefaction indiquant que des manifestations graves seraient a prevoir. Les etudes sur le terrain devraient tenir compte de ces caracteristiques afin de permettre une meilleure evaluation du potentiel de liquefaction sur les sols limoneux. Les essais de penetration au cone (CPT), mini-CPT et forages soniques ne capturent pas correctement les couches minces. Toutefois, la realisation de coupe detaillee d'echantillons de haute qualite permet de saisir les couches in situ reelles qui peuvent aider a expliquer les limites des procedures simplifiees d'evaluation de la liquefaction sur ces sites, ce qui revele la necessite de comprendre les limites sousjacentes des techniques actuelles d'investigation des sites. Les piezometres, les forages soniques, l'echantillonnage de haute qualite, les essais en sondage transversal et les cartes regionales des eaux souterraines sont evalues pour evaluer leur capacite a capter les conditions complexes des eaux souterraines. De multiples methodes de mesurage des eaux souterraines sont generalement necessaires pour caracteriser les fluctuations des eaux souterraines. Il est recommande d'utiliser des outils ameliores de caracterisation des sites pour l'evaluation de la liquefaction des sols limoneux en couches minces et des fluctuations des eaux souterraines. [Traduit par la Redaction] Mots-cles: caracterisation du site, couches minces, sols limoneux, eaux souterraines, liquefaction., Introduction This paper investigates the geotechnical characterization of silty soil sites for liquefaction assessment. The study focuses on sites in Christchurch, New Zealand, where post-earthquake liquefaction manifestations were not observed [...]

The Mw 7.1 Duzce earthquake occurred on 12 November 1999 along the North Anatolian Fault in northwestern Turkey. This paper documents observations from a field reconnaissance team, addressing two principal aspects of this significant earthquake: the recorded ground motions and the distribution and severity of the earthquake effects on the built environment. In general, the recorded ground motions from this earthquake were smaller than predicted by ground motion predictive equations available at the time of the event. One anomalous recording is presented and potential causes for this irregular motion based on observations from field reconnaissance are discussed. The effects of rupture directivity on the near-fault recordings are assessed and the effects of soil conditions on the recorded ground motions are examined. The patterns of building damage based on post-earthquake reconnaissance are presented for the most strongly shaken cities in the near-fault region: Duzce, Kaynasli, and Bolu. Damage in Duzce was concentrated in the southern part of the city, which is underlain by softer sediments. Damage in Bolu was distributed evenly throughout the city; whereas damage was concentrated on more recent alluvial sediments in Kaynasli. No evidence of liquefaction or ground failure was observed in the populated areas surveyed after the earthquake.

Seismic compression is defined as the accrual of contractive volumetric strain in unsaturated soil during strong shaking by earthquakes. We document and analyze two case histories (denoted school site and site A) of ground deformation from seismic compression in canyon fills strongly shaken by the Northridge earthquake. Site A had ground settlements up to about 18 cm, which damaged a structure, while the school site had settlements up to about 6 cm. For each site, we perform decoupled analyses of shear and volumetric strain. Shear strain is calculated using one-dimensional and two-dimensional ground response analyses, while volumetric strain is evaluated from shear strain using material-specific models derived from simple shear laboratory testing that incorporates important effects of fines content and as-compacted density and saturation. Analyses are repeated using a logic tree approach in which weights are assigned to multiple possible realizations of uncertain model parameters. At the school site, predicted settlements appear to be unbiased. At site A, the analyses successfully predict the shape of the settlement profile along a section, but the weighted average predictions are biased slightly too low. We speculate that the apparent site A bias can be explained by limited resolution of the site stratigraphy, bias in laboratory-derived volumetric strain models, and/or uncertainty in the estimated earthquake-induced settlements.

Seismic compression is defined as the accrual of contractive volumetric strains in unsaturated compacted soil during earthquake shaking. Existing seismic compression analysis procedures are based on laboratory test results for clean uniform sands, and their applicability to compacted soils with fines is unclear. We evaluate seismic compression from cyclic simple shear laboratory testing of four compacted soils having fines contents that are sufficiently large that fines control the soil behavior, but possessing varying levels of fines plasticity. Each soil material is compacted to a range of formation dry densities and degrees-of-saturation. The test results show that seismic compression susceptibility decreases with increasing density and decreasing shear strain amplitude. Saturation is also found to be important for soils with moderately plastic fines (plasticity index, PI » 15), but relatively unimportant for soils with low plasticity fines (PI » 2) across the range of saturations tested (³54 %). The saturation effect appears to be linked to the presence or lack of presence of a clod structure in the soil, the clod structure being most pronounced in plastic soils compacted dry of the line-of-optimums or at low densities. Comparisons of test results for soils with and without low- to moderately-plastic fines suggest that fines can decrease the seismic compression potential relative to clean sands.

Ground failure in Adapazari, Turkey during the 1999 Kocaeli earthquake was severe. Hundreds of structures settled, slid, tilted, and collapsed due in part to liquefaction and ground softening. Ground failure was more severe adjacent to and under buildings. The soils that led to severe building damage were generally low plasticity silts. In this paper, the results of a comprehensive investigation of the soils of Adapazari, which included cone penetration test (CPT) profiles followed by borings with standard penetration tests (SPTs) and soil index tests, are presented. The effects of subsurface conditions on the occurrence of ground failure and its resulting effect on building performance are explored through representative case histories. CPT- and SPT-based liquefaction triggering procedures adequately identified soils that liquefied if the clay-size criterion of the Chinese criteria was disregarded. The CPT was able to identify thin seams of loose liquefiable silt, and the SPT (with retrieved samples) allowed for reliable evaluation of the liquefaction susceptibility of fine-grained soils. A well-documented database of in situ and index testing is now available for incorporating in future CPT- and SPT-based liquefaction triggering correlations.

Permanent ground deformations in unsaturated, compacted hillside fills under seismic loading conditions are discussed, with emphasis given to fill performance during the 1994 Northridge earthquake. These movements represent a significant yet often unrecognized hazard to developed hillside areas, as relatively modest deformations induced widespread damage totaling hundreds of millions of dollars during the Northridge event. The development of grading standards in the Los Angeles area is reviewed to place the seismic fill deformation problem in context with other issues that have shaped design and construction practices for hillside fills. Field observational data on fill performance during the Northridge earthquake is presented, and typical ground distress patterns are found to include cracking near cut/fill contacts, lateral extension and settlement of fill pads, and bulging of fill slope faces. For most sites, the prevalent mechanism of permanent ground deformation responsible for the fill movements is contractive volumetric strain accumulation within the unsaturated fill soils during strong earthquake shaking (that is, seismic compression).