The long-term settlement of the ground after the Niigataken Chuetsu-oki Earthquake in 2007 was observed at Shinbashi in Kashiwazaki city. To study the seismic deformation mechanism and long-term post-earthquake settlement, this study carried out ground investigations such as drilling survey on the observation site and indoor element tests for sampled soil. The results showed that the sampled soil was very soft, strongly compressible, and relatively highly-structured. Subsequently, the ground subsidence behavior was simulated through soil-water coupling elastoplastic finite element (FE) analysis using the Transformation Stress-Cyclic Mobility (TS-CM) constitutive model developed by Zhang et al. (2007). The FE simulation results were in good agreement with the on-site site subsidence observation data and the subsequent settlement was predicted forward. Based on the simulation results, sensitivity analysis was conducted on two key parameters λ and κ, and it was concluded that λ is more sensitive to the subsidence amount. In addition, the impact of parameter uncertainty on model uncertainty was also discussed and it was concluded that both λ and κ are moderately conservative and nearly low dispersion for subsidence results, but the dispersion of parameter λ was relatively lower than κ, although parameter λ was more sensitive to the subsidence.

The 2016 M 7.8 Kaikōura earthquake in New Zealand caused severe damage to transport infrastructure across the northeastern South Island from coseismic landslides, debris flows, rock falls, failure of retaining walls, and slumping of embankments. Over 200 km of the road and rail networks were affected, with coseismic landslides blocking the coastal rail and road corridors through Kaikōura for 10 months and 13 months, respectively, causing severe disruption to a nationally important transport route. Compilation of a detailed inventory of over 2,300 slope failures along the transport corridors and back-analysis of selected failed slopes highlights the importance of slope geometry and geological controls on the characteristic failure mechanisms and the consequent impacts on infrastructure. The principal landslide types that caused the most disruption to the transport infrastructure were shallow-seated disaggregated rock avalanches in highly fractured Mesozoic greywacke bedrock and deep-seated structurally controlled slides in greywacke and Tertiary sedimentary rocks. These landslides produced the longest outage time for earthmoving to clear debris and then implementation of engineered risk mitigation measures. Extensive damage to earth fill embankments was also caused by the strong ground shaking, which resulted in difficult access for the initial emergency response and often required lengthy outage for repair of the failed sections. Progressive thickening of the fills for road realignment without geotechnical engineering design, a lack of geogrid reinforcement or subsoil drainage measures, and inclusion of unsuitable soils within the fill materials were all contributing factors to the poor performance of these slopes. The damage caused by cut and fill slope failures in the Kaikōura earthquake highlights the need to understand the key mechanisms driving slope failure, assess the response of slopes to strong ground shaking and the consider the consequences of failure and use a resilience-based framework for slope design, which are lacking from commonly-used design approaches. The findings from this research have been used to develop recommendations for resilient design of slopes and proactive management of landslide hazards along infrastructure corridors.

On February 6, 2023, the Kahramanmaraş earthquakes struck eastern Turkiye, causing significant loss of life and serious damage to infrastructure and buildings. Two main events struck on the same day, both on the East Anatolian Fault. The first was of Mw 7.7 and the second, striking about nine hours later, of Mw 7.6. An extensive area spanning eleven provinces was affected. In March 2023, the UK-based Earthquake Engineering Field Investigation Team (EEFIT) organised a mission that included virtual remote-sensing and field reconnaissance teams. Remote-sensing, with high resolution Maxar Open Data Program satellite imagery, identified areas severely affected by geotechnical hazards and associated failures prior to the field visit. Field reconnaissance then undertook detailed technical evaluation and data collection to assess the characteristics of the observed geotechnical hazards, the performance of structures and their foundations, and the effectiveness of associated design codes. In this paper, we present the major geotechnical observations from this mission. Our observations cover a multitude of geotechnical failures, including landslides and rockfalls, liquefaction and subsidence, lateral spreading, as well as fault surface rupture and interaction with buildings. General conclusions about specific design types and practices are given at the end of the paper.

The 2023 Kahramanmaras earthquake sequence produced extensive liquefaction-induced ground deformations along the infilled shoreline of the port city of Iskenderun, Turkiye. Observed liquefaction effects included ground settlement, seaward lateral spreading, and failures along a rubble mound seawall lining the coast. These effects, among other factors, likely contributed to ongoing flooding in Iskenderun during moderate storm and high tide events following the earthquakes. The Geotechnical Extreme Events Reconnaissance (GEER) team collected detailed observations and measurements of selected sites affected by liquefaction. This paper presents lateral spreading, ground settlement, and flooding observations in Iskenderun, which suggest widespread movements of the coastline relative to the current sea level. The Dogan restaurant case history is described in detail, where earthquake ground deformations and subsequent flooding damaged a dining patio, seawall, and nearby park facilities. Insights from these observations suggest a need to better understand multi-hazard liquefaction and flood consequences to enhance the resilience of coastal cities.

Geotechnical damage resulting from the 2023 Turkey-Syria earthquake reported here is summarized as follows: A landslide dam was formed in Islahiye because of the earthquake. In Tepehan, a landslide occurred on a relatively gentle limestone slope, possibly linked to fault movements in the area. Iskenderun experienced building collapses on soft ground, along with building tilts and ground subsidence. These phenomena were caused by the liquefaction of reclaimed coastal land. Golbasi witnessed significant damage due to liquefaction in structures with shallow foundations on soft ground. This damage involved the tilting and settling of buildings. Further investigation is necessary to accurately map the extent of liquefied soil layers in this region. These geotechnical damages underscore the diverse and complex impacts of the earthquake on various soil types and geological conditions across different areas. Comprehensive investigations are crucial for understanding the specific mechanisms and vulnerabilities that led to these damages, as well as for developing strategies to mitigate similar risks in the future.

On February 6, 2023 Eastern Türkiye was shaken by two consecutive catastrophic earthquakes of moment magnitudes 7.7. and 7.6, induced by a left-lateral strike-slip fault in Eastern Anatolian Fault Zone. The first earthquake with a moment magnitude 7.6 was felt at 4:17 local time in the morning, while, approximately nine hours later, the second earthquake with a moment magnitude 7.7 increased the massive damage that occurred in eleven provinces of Turkiye including Hatay, Kahramanmaras, Adiyaman, Malatya, Osmaniye, Gaziantep, Kilis, Sanliurfa, Diyarbakir, Adana and Elazig. In this paper, a specific focus is devoted to show the site effects observed in Antakya after the strong shakings as revealed by an extensive analysis of the collected ground motion records and geological and geotechnical data. It is shown that basin effects are associated with a higher level of damage compared to areas with the same level of ground shaking but without detrimental conditions of the local soils. The lessons learned from this seismic event highlight the key role played by the seismic response analysis and related tools of microzonation studies for the mitigation of the seismic risk.