When constructing a building on a site with a soft ground layer on top of a sloping bedrock (supporting layer), a pile foundation with mixed piles of different lengths is often used. In this paper, the seismic response of pile-supported buildings constructed on a sloping bedrock is analyzed by the shaking table model test. In the test, excitations in the sloping direction of the bedrock surface and in the direction perpendicular to the slope were conducted. Test results showed that for the specimen with sloping bedrock, the effect of the constraint condition at the pile tip became noticeable as the input amplitude increased and the ground became non-linear, and the bending moment at the pile tip increased for the short piles. In addition, it was shown that the characteristics of pile-soil springs are different from those of the parallel stratified ground due to the presence of bedrock near the tip of the short piles. Additionally, it was confirmed that the characteristics of the pile-soil springs depend on whether the excitation exists in the sloping direction or perpendicular to the slope, or whether the pile becomes the leading or the trailing pile.

The Geospatial Information Authority of Japan (GSI) developed the Seismic Ground Disaster Assessment System (SGDAS) in 2012 for the purpose of disaster response immediately after an earthquake, even at night, and it became officially operational in June 2019. SGDAS automatically estimates the area and scale of landslides and liquefaction after receiving seismic intensity distribution data, and generates a PDF report and sends emails to disaster response administrative officials. However, SGDAS was developed more than 10 years ago with data up to 2012, and subsequent disasters were not considered. Therefore, we are currently carrying out a five-year R&D project (FY 2021-25) to improve the estimation accuracy of the system. The project began with statistical comparison of damage maps of ground disasters and landslide/liquefaction estimation results to assess the current state and future directions. The results indicate needs for a new zoning of geological and geomorphological conditions based on the amount and type of landslides, additional information on seismic shaking, and a geomorphological map with better representation of small landforms in plains. We also conducted user questionnaires and interviews to understand user needs, which showed that oversight was more problematic than overestimation. We hope that our experiences will be useful to many other countries and institutions facing similar challenges.

The effect of crustal fluid was investigated for the spontaneous dynamic fault rupture simulation without giving a priori rupture starting area and rupture stopping area. We considered the crustal fluid that had higher pressure than the groundwater pressure on the fault plane. Under the condition, our dynamic fault rupture simulation was able to reproduce that the spontaneous initial rupture occurred, and after the rupture propagated along the fault plane, and then the spontaneous rupture stopped. It was shown that the rupture propagation velocity, slip displacement, slip velocity, etc. were consistent with the results obtained from the inversion analysis of actual inland crustal earthquakes. Using the dynamic fault rupture simulation, the authors showed that the crustal fluid had a significant effect on the fault rupture.

It is thought that the liquefaction resistance increases in the ground once liquefied because the ground becomes denser due to the drainage of pore water. However, it has been reported that re-liquefaction occurs in liquefied ground. In this study, liquefaction and re-liquefaction characteristics were evaluated using two kinds of undisturbed and its reconstituted samples collected from grounds filled with volcanic ash soil in Sapporo and Kitami Cities, Hokkaido, Japan. In addition, the change of stiffness due to liquefaction was investigated by the bender element test. Test results showed that; 1) In the reconstituted sample, the re-liquefaction strength increased slightly due to the density increase during liquefaction. On the other hand, the re-liquefaction strength of the undisturbed sample was lower than the first liquefaction strength. 2) The anisotropy of the sedimentary structure did not change before and after liquefaction in both the undisturbed and reconstructed samples. It wasthought that the contact force between particles decreased while the initial anisotropy was maintained.

Since 2001, the Dobutsu seismic intensity observation station has recorded strong ground motions with the intensity of ≥5 on the Japan Meteorological Agency (JMA) seismic intensity scale for 13 times. Moreover, weak to strong seismic motions have been recorded. In this study, the amplitude dependence of the site response was investigated using earthquake records at the Dobutsu station. First, boring and microtremor surveys were conducted. Then, seven strong motion records and ten weak motion records were analyzed. Finally, the horizontal-to-vertical spectral ratio of earthquake motion was used to confirm the amplitude dependence. Results showed that the peak frequency, F_p, during weak motions is 1.6 Hz but it becomes 1.4 Hz when the peak ground velocity is ~20 cm/s.

Monotonic and cyclic triaxial tests were performed on decomposed granite soil (Masado) sampled from Kagawa Prefecture. The effects of the degree of compaction (Dc) and hydrogen peroxide (H₂O₂) injection on the shearing properties of this soil were considered. The chemical weathering of Masado was simulated by reacting the soil with H₂O₂ to oxidize it. The present study was conducted to understand the effects of soil compressibility and chemical weathering on the monotonic and cyclic undrained shear behaviors of soils. In addition, a series of undrained cyclic triaxial tests, followed by monotonic loading, were conducted on the soil to evaluate the post-liquefaction behavior. The cyclic shear strength of Masado at Dc = 100 % tended to decrease with increasing H₂O₂ injection. For the postliquefaction characteristics of Masado at Dc = 100 %, as liquefaction resistance factor FL decreased, the stiffness in the small-stiffness region declined and strain in the low-stiffness region increased. The behavior after liquefaction was only slightly affected by chemical weathering.

In the 1995 Kobe Earthquake disaster, the roads and railway facilities in the Kobe area experienced severe damage. And, in the disaster emergency response and restoration process of these lifeline facilities, it has been reported that damage to roads and railways have interrelationship effect (interaction) to the damage in different type of lifelines, such as electricity, gas, water, sewers, telephones. Even now, about 30 years after the case in Kobe, it is easy to imagine that similar phenomenon will occur in case of a large earthquake disaster. The Lifeline Network Kansai (LiNK), which consists of lifeline related organizations and researchers in the Kansai region, examined the past damage and the current installed countermeasures, and the possible interaction of various types of lifeline systems.

The 1995 Hyogo-ken Nanbu earthquake caused extensive damage to various lifeline facilities. It has been reported that interconnected problems occurred among lifelines in disaster response and restoration. After nearly 30 years, a similar situation will occur if a large city was hit by a large earthquake. However, the way of the disaster may be different from the past cases. The Lifeline Network, Kansai (LiNK), which consists of lifeline operators and researchers in the Kansai region, re-examined the past damage and the current state of countermeasures. Also, the possible interconnected problems at present are discussed. This paper focuses on communication systems, and the important interconnected problems among lifelines are summarized.

Lifeline facilities were severely damaged in 1995 Kobe earthquake disaster. And it has been reported that the emergency response and restoration process of lifelines suffered from the interconnection problems. Even now, almost 30 years after the Kobe case, it is easy to imagine that a similar phenomenon will occur in an earthquake disaster. In this study, the experts, and researchers in Lifeline Network Kansai (LiNK), examined the past damage cases and the status of countermeasures in Kobe area. In this paper, we present the results of the study of interconnection problems on energy related lifelines such as electricity and gas.

In the 1995 Kobe Earthquake disaster, the water supply networks in the Kobe area experienced severe damage. And, in the disaster emergency response and restoration process of these lifeline facilities, it has been reported that damage to water supply networks have interrelationships effect to the damage in different type of lifelines, such as sewerage, roads, railroads, telephones, communication systems, electric power and gas. Even now, about 30 years after the 1995 Kobe Earthquake disaster, it is easy to imagine that similar phenomenon will occur in case of a large earthquake disaster. The Lifeline Network Kansai (LiNK), which consists of lifeline related organizations and researchers in the Kansai region, examined the past damage and the current installed countermeasures, and the possible interrelationship effect of various types of lifeline networks.

In the emergency response to the lifeline damage in 1995 Kobe Earthquake Disaster and restoration works of these damage to lifeline facilities after the earthquake, the interconnection problems of lifelines were reported. Even now, almost 30 years after the Kobe earthquake case, similar problems will occur in case of an earthquake. However, the details of the interconnection problems may be different from the past cases. From this viewpoint, the member of Lifeline Network, Kansai (LiNK) examined the past damage and the current status of countermeasures. In this paper, the results of the study on the past damage and possible interconnection problems in future on sewers and waste disposal operations are summarized.

In order to examine the possible source of microtremors, we investigated the variation of the ground acceleration levels at 47 points in Kanto area. Urbanization rate around the site, site amplification factors, distance from major roads were considered as the possible factor on the level of microtremor. In addition, seasonal change on the level of microtoremors, and the effect of the declaration of emergency states due to COVID-19 on the level of microtoremors, were investigated. However, there are no significant relationship between the level of microtremor and possible factors considered in the study, and there are quite small variations as the seasonal change and the effect of COVID-19 compared to the daily change and site difference.

Devastating earthquakes, such as those that recently affected Turkey and Morocco in 2023, are among the deadliest natural disasters. In addition, liquefaction-induced damage induced by strong shakings further exacerbates economic losses and elongates the repairing time for structures and infrastructures. Consequently, improving foundation soils and strengthening structural elements are possible ways to enhance the resilient capacity of a building to resist seismic forces. The main goal of this study is to numerically investigate the behaviour of innovative synthetic materials, made by a mixture of gravel and granulated rubber, used as geotechnical seismic isolation (GSI) systems relevant to the mitigation of seismic risk. To this aim, numerical simulations of a well-known and instrumented gravelly site affected by liquefaction during the 1995 Kobe earthquake are performed using a pore water pressure model implemented in one of the most popular nonlinear software adopted for dynamic analyses. The analyses were carried out with and without soil treatment made by a mixture of gravel and rubber, showing the efficacy of the proposed intervention. The result of the study contributes to expanding the knowledge about mixture-composite materials and assessing the gravel-rubber mixtures (GRMs) as an effective mitigation treatment of seismic risk.

This study looks at submarine landslides, which can cause tsunamis and coastal damage worldwide. While submarine landslides are less studied in Korea compared to landslides on land, they are increasingly important due to global tsunami risks. The Korean Peninsula's eastern region, including the Ulleung Basin, has steep terrain and frequent mid-sized earthquakes, making it prone to submarine landslides. Previous research has identified the topographical features and soil properties of these landslide-prone areas in the East Sea. This study focuses on selecting a representative cross-section and geological characteristics of the Ulleung Basin region to conduct dynamic model tests for better understanding and preparedness. The study area is the Ulleung Basin in the East Sea, where submarine landslides are likely to occur, especially along the southwestern border area. The topography here is steep, making it suitable for studying submarine landslides. The 12MAP-53 measurement line was chosen for analysis, as it exhibits significant steepness compared to its surroundings. Selecting the right cross-section to represent submarine landslides is crucial. Boring tests were conducted along this line to understand the seafloor topography. The area mainly consists of clay sediments, with some clay-sand mixture in the upper parts of the slope. For the model tests, kaolinite, a common clay mineral, was selected as the representative geology. Before conducting experiments, various tests were performed on the kaolinite soil, including specific gravity, Atterberg limit, sieve and hydrometer analysis, consolidation test, and direct shear test. These tests provided essential data for the experiments, ensuring that the chosen soil type was suitable for the study. Creating a model slope for dynamic testing involved shaping consolidated kaolin slurry. Silica sand was used for a stable base, and a load of 0.05 kg/cm2 was applied to achieve the desired strength. Natural frequency of the model slope, crucial for understanding its behavior during testing, was determined to be 36.6 Hz. While the study is ongoing, future experiments will involve dynamic testing using a shaking table to simulate real-world conditions.

The material attenuation characteristics of the ground, which are necessary for predicting the propagation of vibrations in the ground, were obtained through laboratory tests using cylindrical specimens. Shear waves were focused on as the vibration propagating in the ground, and multiple pulses of vibration were generated by electrical excitation, and the amplitude attenuation was evaluated by discrete Fourier transform of the vibration at both ends of the specimen. The frequency-independent material attenuation constant α₀=πη/V was measured from the wavenumber conversion of the propagation distance and amplitude ratio. As the ground material, dry silica sand No. 4, No. 8, and sample sand from a field conducted in Abira, Hokkaido, Japan, were used. The test results of the sample sand were compared with the results of vibration propagation field test.

Four decades after the introduction of the high frequency spectral decay parameter kappa (κ) to the scientific community, there has been relevant progress on our understanding of how it captures seismic attenuation and its multiple applications in stochastic modeling of ground motions, seismic hazard assessment, and site response analysis. Particularly, κ’s site-specific component, κ₀, has been used to characterize near-surface attenuation, which offers additional information to site response analysis and site-specific seismic hazard assessments beyond that provided by other site parameters such as the average shear wave velocity over the top 30 m of a site (V_s30). The Japanese database KiK-net is rich with a dense array of stations (at the ground surface and at depth) providing thousands of high-quality ground motions. However, the unclear underlying physics of κ and its associated variabilities pose challenges to its further application in site-specific seismic hazard assessments. Thus, the objective of this work is to identify the current limitations and challenges for near-surface attenuation characterizations with κ. The downhole array of KiK-net allows to study the response of soil mediums between surface and borehole sensors directly. The difference between surface and borehole individual κ estimates (what we referred to as Dκ₀), could capture the seismic attenuations contributed from the soil column between those two sensors. Larger borehole κ values (i.e., leading to negative Dκ₀) are the focus of this study because Dκ₀ is expected to be positive. With the assumptions that κ could serve as an attenuation parameter to characterize the dissipations of seismic wave energy, the negative Dκ₀ are lack of physical explanations. The observation of larger κ estimates at depth compared to their counterparts at the ground surface (i.e., negative Dκ₀) could result from multiple reasons. In this work, we specifically study the influences of ground motion directionality and site amplifications on Dκ₀ estimates. A single KiK-net station was selected for this case study to figure out the main challenges that remain in characterizing near-surface attenuation with κ.

Fragile geologic features have been previously identified as potentially useful for validating un-exceeded ground motions estimated from PSHA models. The two potential seismic sources in southern Israel (Negev Desert) are the Dead Sea Transform (DST), an active tectonic border, and the Sinai-Negev Shear Zone (SNSZ). For the DST, an M 7 with a return period of 500 years was proposed, and for the SNS, an upper bound of M 6.2 was suggested. Here we present a study of the dynamic fragility of a freestanding rock pillar in the Negev Desert to access the peak ground motion in the region. The Ramon pillar is 42 m high, with a 0.12 slenderness ratio, comprised of discontinuous, hard carbonate rock. The fragility age (OSL dating) of the pillar is 11,000 years. Free vibrations of the Ramon pillar were measured using a broadband seismometer placed on its top, with a simultaneous measurement on the parent cliff. The pillar was aerially scanned using UAV-born Lidar and photogrammetry to produce an accurate 3-D model. Rock mass stiffness was measured in-situ for the entire height of the pillar. Based on the scan and measurements, a Finite Element (FE) model of the pillar was developed. The model was validated by comparing FE modal analysis and free vibration measurements. Following validation, a dynamic analysis of selected M 7 and M 6.2 earthquakes was performed. It was found that an M 6.2 on the SNSZ (R_Rup < 10 km) would most probably lead to the collapse of the pillar, and therefore the occurrence of such an earthquake during the past 11,000 years is not probable.

Sedimentary materials enclosed in basins modify the ground motion by energy trapping, resonance and surface wave generation at the basin edge. In general, the effects of basin presence are approximated by aggravation factors (AGF), but the particular surface wave part of the ground motion is never explicitly measured. The current study assesses the impact of basin effects on the seismic damage of a nonlinear structure, representing a bridge column, using a complete time-analysis from the earthquake source to the structure. The numerical wave propagation simulation is performed with a coupled 3D SEM-FEM approach using the Domain Reduction Method (DRM), including non-linearities in the structure. Therefore, with this model, the coupled basin effects on the seismic hazard and on the structural demand are quantified and contrasted. The findings indicate that basins' effect on structural damage may be estimated in a simplified form using a combination of a structural behaviour predictor and AFs derived from the free-field ground motions. However, these factors should be correctly predicted, including both basin and source variability.

The economic and environment-friendly design of foundations without compensating the load-bearing capacity is an issue of concern for most geotechnical engineers worldwide. Ring Foundation is one such foundation that has been designed for supporting heavy or large structures such as silos, wind turbines, bridges, towers, etc, where the conventional shallow foundation is unable to provide the required support. Ring foundations are more economical to build since they use less material than other shallow foundations, which also reduces the carbon emissions caused by the production of cement. These types of foundations enable more even load distribution and improved lateral force and bending moment resistance, which leads to reduced settlement and increased stability. The numerical and experimental study of the bearing capacity of the ring foundations has been performed in the past but the settlement prediction of these foundations is still neglected. This paper focuses on the settlement prediction of the ring foundation on a homogenous cohesionless medium under dynamic loading using pseudo static analysis. A simple 3-Dimensional (3D) numerical model in ABAQUS Cae software is used for the analysis. The effect of variation of the seismic acceleration coefficients (k_h and k_v), the friction angle (Φ) of the soil, and the loading pattern on the settlement of the ring foundation have been studied.

Pre-ground improvement is an auxiliary method for shallow overburden tunnels in which the tunnel excavation is performed after improving the ground on top of the tunnel with/without sides by the replacement method and/or the cement mixing method. Although it has been confirmed in previous studies that pre-ground improvement enhances the tunnel face stability and reduces the settlement of the ground surface during the tunnel excavation, the seismic behavior of tunnels with pre-ground improvement has not been fully investigated. In this study, a two-dimensional elasto-plastic finite element analysis is performed on an actual reinforced concrete shallow overburden tunnel with a ground improvement. The damage of the reinforced concrete tunnel during earthquakes is discussed in detail.

This contribution presents a statistical analysis of the non-linear behavior that can be detected on strong motion recordings obtained on thick Japanese sedimentary sites from the KiK-net and K-NET networks, together with a comparison with other site types involving thinner deposits and/or higher fundamental frequencies. The non-linear effects are quantified by comparing various kinds of site-response characteristics (surface-to-borehole spectral ratios, H/V spectral ratios) for moderate to large motion to their weak motion counterparts. While a non-linear behavior can be detected on thick and thin sites as well, thick sites do not exhibit the peculiar high-frequency reduction predicted by most non-linear simulations because of increased damping. This inconsistency constitutes a warning on the use of classical non-linear degradation curves derived from measurements at limited confining pressures corresponding to depths not exceeding a hundred meters.

On 18 June 2018, an M_w 5.5 inland crustal earthquake occurred in the northern Osaka Prefecture, Japan. This event is one of the most disastrous earthquakes bringing large ground motions with a maximum observed intensity of 6-lower on the Japan Meteorological Agency scale in and around the metropolitan Osaka area. Strong ground motions with larger peak ground accelerations and velocities than those expected by the ground motion model were observed in the south-west direction from the source. In order to understand the strong motion generation process during this event, the source model was estimated on the basis of broadband strong-motion waveform modeling using the empirical Green’s function method. We assumed two fault planes with different fault types, according to both the relocated aftershock distribution and source mechanism solutions. The source model wasrepresented by two patch-shaped strong motion generation areas (SMGAs) to explain the observed ground motions in 0.4–10 Hz. First, the ‘SMGA1’ with reverse slip on the fault segment striking with N356°E was ruptured propagating northward from the hypocenter. Second, the ‘SMGA2’ with strike-slip on the fault segment striking with N49°E was ruptured propagating southwestward from the hypocenter with a delay time of 0.2 sec after starting the rupture on SMGA1. From the ground motion simulations considering these two SMGAs, we found the strong pulse observed in northern Osaka was caused by the forward rupture directivity effect generated on the SMGA2. The stress drops of SMGA1 and 2 were estimated 13.9 and 14.9 MPa, respectively, which are comparable to the average value of the SMGA model for past inland crustal earthquakes in Japan. It is also important to discuss the effect of ground motion amplification due to the Osaka sedimentary basin, for further understanding of large ground motions in northern Osaka caused by this earthquake.

With increased demand for urban space, there is a growing propensity to move urban lifeline systems like Metro systems, power, and water cables etc. to shallow, cut-and-cover tunnels. The seismic behaviour of such rectangular tunnels is important as these systems need to remain operational in the period after the earthquake for emergency rescue & recovery operations. Due to the large longitudinal extent of the tunnels, they pass through varying geological formations that can vary from loose, saturated sands to soft clay layers. In this paper, the main focus will be on determining the seismic response of shallow, rectangular tunnels that are passing through liquefiable, loose sand layers and very soft clay layers. The results from two separate centrifuge testing campaigns will be presented. The dynamic response of the tunnel will be compared to the input motion. The tunnel movement during seismic loading were obtained using high-resolution, high-speed imaging in combination with GeoPIV-RG software, as well as the linear variable differential transformers (LVDT). The uplift of the tunnel structure during the earthquake loading due to its high buoyancy relative to the soil body will be discussed. Finally, conclusions will be drawn on the effect of the soil strata through which the tunnel passes, based on the centrifuge data from loose, saturated sand, and soft clay tests.

The phenomena that occur inside the ground must be clearly understood and modeled to evaluate ground stability. However, it has been difficult to evaluate structural changes with the progression of destruction in the same specimen because it is necessary to physically cut open the specimen to understand the internal materials conditions. This study examined the formation mechanism of shear zones in the ground caused by external forces associated with earthquakes. We conducted a ring shear experiment to reproduce large deformations in a laboratory and used microfocus X-ray computed tomography (CT) to clearly and nondestructively visualize the interior of specimens. The microscopic structure of the shear zone was quantitatively evaluated by analyzing CT images. As shearing progressed, the porosity in the shear zone and its variability increased and the direction of the particles changed. The long axis of the particles shifted to the direction of shear in the horizontal cross section and to the horizontal direction in the vertical cross section. These results can contribute to the improvement of the stress strain models of geomaterials and provide important information for evaluating the stability of geomaterials against earthquakes.

Local soil conditions play an important role in regional seismic hazard assessments due to their influence on earthquake-induced ground shaking and deformation. The different levels of damage and site response at nearby locations correlate to site and geologic conditions variability, as has been reported after past earthquakes. Evaluating spatially variable ground motions (GMs) is key for earthquake reconnaissance efforts and regional seismic hazard assessments. This study focuses on the evaluation of spatial correlations in site parameters (e.g. time-averaged shear-wave velocity to a depth of 30 meters) at Kiban-Kyoshin Network (KiK-net), and their comparison to the observed spatial correlation of the residuals from ground motion intensity measures (IMs) from the Mw9.1 Tohoku earthquake. Current spatial correlation models treat site effects either as a fixed amplification factor or as randomized amplifications, but site effects are neither fixed nor random. Hence, geostatistical methods are used here to estimate spatial correlations between parameters that control site response and integrate their effects on resulting spatially variable ground motions. In this work, we evaluate the significance of the spatial correlation for different site parameters with respect to the GM amplification IMs residuals.

The paper summarises the main findings of a parametric numerical investigation focusing on the seismic response of the foundation soil below the Two Towers, the historic medieval symbol of Bologna (Italy), dated back to the XII century. The fine-grained strata were recently characterised by an experimental field campaign down to 40 m below the ground level (b.g.l.), providing a shear wave velocity profile not exceeding 400 m/s. The seismic geotechnical model was then extrapolated down to either 150 m or 230 m b.g.l., where the presence of a rigid bedrock was assumed on the basis of geological considerations, with modest effects on the final outcome though. Analyses were run in the frequency domain with the code MARTA, using an equivalent linear visco-elastic law for the soil, and in the time domain with the finite element code PLAXIS, using instead the hardening soil model with small strain stiffness. The seven selected seismic inputs were scaled to a peak ground acceleration equal to 0.191 g, in order to be representative of the earthquake reference hazard scenario of the site for a return period of 712 years. Results at the tower embedded foundation depth (i.e. 5 m b.g.l.) clearly indicate that, while the peak ground acceleration is approximately coincident with the input, a significant seismic amplification can be observed at the fundamental periods of the Two Towers (about 1.35 s for the Garisenda and 3.00 s for the Asinelli). Larger values of spectral accelerations and maximum shear strains, also exceeding 0.1% in the shallower layers, are typically predicted by PLAXIS, thus highlighting the importance of adopting a more advanced constitutive formulation in the context of strong earthquake excitations.

The area where tunnels crossing faults may suffer from severe damage during earthquakes. For fault-crossing tunnels, it is inevitable to be subjected to near-fault earthquake motions when the nearby faults rupture. However, current research rarely considers the impact of near-field motions in seismic analyses of fault-crossing tunnels. In this study, shaking table tests were conducted to investigate the seismic response of fault-crossing tunnels. Both near-fault motion and far-fault motion were adopted as input motions for a comparative analysis of fault site response and tunnel response. The findings reveal a discernible difference in the seismic responses of fault-crossing tunnels subjected to near-fault and far-fault motions. Given equivalent input peak ground acceleration (PGA), near-fault motion markedly amplifies both the acceleration amplification factor, the deformational response, and Arias intensity the fault-crossing tunnel. Furthermore, the origins of this amplification effect can be attributed to two elements: the richer low-frequency components inherent in near-fault motions and the higher PGV/PGA ratio.

Coastal zones are vital economic resources for many countries, with opportunities for tourism, fishing, transportation, and trade. However, the susceptibility of these areas to seismic hazards such as liquefaction and tsunamis exhibits a significant challenge to sustainable development and economic growth. Thus, identifying the geotechnical conditions that contribute to seismic vulnerability and the definition of high-risk areas are crucial steps for coastal infrastructure development planning. In Mexico, coastal areas along the Pacific Ocean are highly susceptible to seismic hazards, due to their proximity to active subduction zones, which have produced some of the most devastating earthquakes. Likewise, the presence of loose and saturated sediments, associated with the proximity of these coastal communities to the ocean, increases the risks of liquefaction and tsunami-induced ground deformation. In recent years, both phenomena have been observed after seismic events in several locations along this region. This paper examines the impact of the Mw 7.7 Michoacan earthquake that occurred on September 19, 2022, in Mexico, which triggered liquefaction in several coastal areas and activated a tsunami alert in four states on the Mexican Pacific Ocean coast. Key findings highlight crucial factors contributing to seismic hazards and provide insights for identifying vulnerable areas for future coastal infrastructure development. In addition, a five steps methodology for analyzing tsunami induced damage is described.

Seismic performance evaluation of on-ground structures can be significantly affected by their interaction with underground structures. This effect becomes more relevant in densely populated areas where transportation systems such as tunnel metro lines and stations are located nearby urban bridges, and buildings. This paper presents the findings of a numerical study carried out to conduct the seismic evaluation of a typical urban bridge-building-tunnel system, located in the high plasticity Mexico City clays. Through a series of three-dimensional finite difference numerical models developed with the software FLAC^3D, both detrimental and beneficial interactions effects among these structures are analyzed, establishing zones around each structure in which this interaction leads to ground motion variability, as well as the impact on both the building and bridge seismic performance. The parametric study was carried out considering both normal and subduction events for a return period of 250 years. Distances among each structure were varied to cover a wide range of scenarios and to narrow potential interaction effects. From the results gathered here, the effect of this interaction on the modification of building and bridge accelerations, and displacements, and, in turn, the seismic demand in on-ground structures due to underground structures, was established.