Tsunami Loads Research Articles

Experimental study of dam-break-like tsunami loads on vertical structures with overhanging horizontal slabs: Slab with air chamber

Tsunamis pose a significant threat to coastal engineering. A comprehensive physical experiment was conducted to examine the effect of air chambers on vertical structures with overhanging horizontal slabs under tsunami bores. This paper, serving as the second part of the series, contrasts with conditions without air chambers (flat slab as Part I) to underscore the chamber's effects. The experiment employed dam-break waves to simulate tsunamis, and the collected pressure data and experimental images were analyzed. Results show that the chambers restrict water flow, thereby enhancing the impact on the slab. This focusing effect greatly increases both maximum uplift and horizontal pressure (by almost 1.3 times). The uplift pressure rises with increasing chamber volume, while horizontal pressure escalates with greater beam volume. However, both pressures diminish as slab height increases. Water flowing into the chambers disperses air, generating numerous bubbles that accumulate above, forming an air layer that reduces pressure signal fluctuations. This phenomenon of entrained and trapped air is compared and analyzed with existing literature. The maximum pressure of the nearshore air chamber is greater than that of the offshore air chamber by 13% (3.68 kPa vs. 3.27 kPa), while the quasi-steady pressures of the two are almost equal. Differences in pressure between chambers result from the sequence of water flow impacts and reflections. New design envelope equations and conversion coefficients are proposed based on experimental data. The focusing coefficient, considering bore height, slab height, and chamber parameters, is summarized. Novel equations for estimating pressure on a flat slab with specific chambers are proposed, with validation results indicating high accuracy.

Experimental and numerical study on failure mechanism of steel cylindrical tanks subjected to earthquake-tsunami sequence

In coastal areas, earthquakes are very likely to cause deformation of the seafloor crust, which in turn triggers large-scale water displacement and forms tsunamis. Structural damage caused by an earthquake may diminish the resistance of steel cylindrical tanks to tsunami impact, resulting in more pronounced failure behavior. In this study, a sequential loading experimental program and corresponding Coupled Eulerian Lagrangian-based numerical model are developed to investigate the failure mechanism of steel cylindrical tanks subjected to earthquake-tsunami sequence. To be specific, failure characteristics of tank models under isolated tsunami loading are examined through experiments with different solitary wave heights and water velocities. The damage amplification effect of seismic pre-damage on subsequent tsunami impact is compared by subjecting earthquake-damaged tanks to tsunami loading. Results indicate that seismic-damaged tanks exhibit more significant failure behavior due to factors such as geometric deformation, residual stress, and wave breaking. Specifically, the protruding edges caused by seismic pre-damage induce concentrated stress, leading to higher maximum stresses and more pronounced displacement changes in the tank walls. Compared with considering the individual tsunami hazard only, peak displacement failure amplification exhibits fluctuations ranging from 17.1% to 94.5%, while peak stress amplification factors varied between 4.5% and 158.3%. This work lays the groundwork for overcoming the limitations of traditional single-hazard fragility analyses.

Tsunami Debris Damming Drag Forces And Associated Coefficients On Elevated Coastal Structure Columns

Tsunami overland flow induces hydrodynamic loads on coastal structures and may transport various objects located within the inundation zone, which could become debris and exacerbate hydrodynamic loading. In the process of adopting “the first national, consensus-based standard for tsunami resilience” (Chock, 2016) in the form of ASCE 7-16 Chapter 6: Tsunami Loads and Effects, emphasis was placed on evaluating debris transport and impact forces. This is evidenced by the robust body of literature regarding physical model experiments of these processes and thorough design procedures for both load considerations in current structural engineering standards (ASCE, 2022). Debris damming forces, resultant of debris being transported and accumulating against structures, are less thoroughly studied, having only recently begun to transition from steady flow experiments to transient flow conditions representative of coastal inundation events. A recent pair of experiments bridges this gap, comparing debris damming via steady-state, subcritical flow conditions to that caused by a dam-break style hydraulic bore (Stolle et al., 2018). That paper aimed to study debris dam formation, stability, and loading as well as runup of the flow onto idealized structural columns. Another study varied debris quantity, orientation, and arrangement to determine the effect had on damming and impact loads (Shekhar et al., 2020), however neither compared findings to current standards. The experimental work presented herein represents initial findings of a multi-year experimental campaign to better understand the mechanisms that lead to debris damming and increased structural loading. This work builds upon previous studies by using larger scale debris elements, more numerous debris fields, and more trials to better model such a stochastic process as debris damming. Three different incident wave conditions also led to varied hydrodynamics at the column specimen. In later phases, this campaign will also investigate the debris damming consequences of heterogeneous debris, which more accurately represent highly variable debris fields observed in post-event site surveys (Nistor et al., 2017). This paper aims to compare experimental debris dam loading parameters to those in the current ASCE 7-22 standard (ASCE, 2022). Namely, evaluating conservatism of ASCE 7-22 design values for: overall drag force on buildings, minimum closure ratios used in load determination, and empirical rectilinear structure drag coefficients during both debris accumulation and quasi-steady debris damming phases.

Experimental and numerical investigation of fairing countermeasure for tsunami forces on three different types of bridge superstructure

By extending Wu et al. (2023)'s research of reducing tsunami loads on bridge decks through fairings and openings, this study aims to optimize fairing designs for three typical bridge superstructures, i.e., T-girders, Single-box girders, and Multi-box girders, and assess the effectiveness of fairings in mitigating hydrodynamic forces from extreme waves. A comprehensive methodology including both experimental testing and numerical simulations is adopted and the load reduction capabilities of fairings for bridge girders is evaluated, where an active machine learning model is utilized to identify the optimal fairing configurations for each bridge type. Key findings include: (a) Well-designed fairings can substantially reduce both horizontal and vertical wave loads, simultaneously avoiding potential structural damages from openings; (b) Under the investigated tsunami bore wave conditions, as the incident tsunami bore wave height increases, the horizontal and vertical forces acting on the fairing structures significantly increase, highlighting the importance of considering these loads in the fairing design; and (c) For the studied three bridge deck structures with the same width and height dimensions, the observed variations in the optimal fairing configurations are minimal, indicating a feasible potential for the standardized implementation of fairing in practical engineering.

Damage Spectra of SDOF Structures Under Tsunami Actions Considering the Nonlinear Dynamic Analysis Method

This paper studies the damage spectra of single-degree-of-freedom (SDOF) systems for tsunami loading. The 2011 Tohoku tsunami wave traces are computed and obtained by adopting the Cornell Multi-grid Coupled Tsunami (COMCOT) model and are further verified by the Tohoku Tsunami Joint Survey (TTJS) data. The tsunami response analyses of SDOF systems are conducted taking into account the dynamic analysis method. The classical ductility damage is considered as the damage performance. The damage spectra are computed for five force reduction factors and 791 tsunami loadings. The effects of inundation depths, hysteretic model, post-yield stiffness ratio, [Formula: see text], viscous damping ratio, [Formula: see text], are explored and interpreted scientifically and statistically. The results demonstrate that the effect of the hysteretic model, force reduction factor, R, post-yield stiffness ratio, [Formula: see text], viscous damping ratio, [Formula: see text], on the damage of the structure is evident. Comparison with the static method and influence analysis of structural damping indicate the necessity for the application of the dynamic method. A simplified predictive formulation is developed for the evaluation of structural damage for tsunami loadings.

A numerical methodology for estimating site-specific cascading earthquake and tsunami dynamic loading on critical infrastructure

A numerical methodology for deriving cascading earthquake and tsunami loading patterns for use in critical infrastructure design is proposed. Earthquake source parameters are first used to generate synthetic ground motion acceleration time series at the site of a critical infrastructure using an open-source stochastic extended finite-source simulation algorithm. Using the same earthquake source information, the tsunami phases of generation, propagation, and inundation are modeled using a coupling approach for determining tsunami wave forces. The coupling approach combines (1) a code based on non-linear shallow water equations solved by the Finite Volume method, which is used to capture the tsunami flow characteristics from generation through the inundation phase until relatively close to the structure, coupled with (2) an open-source computational fluid simulation code, which relies on solving the Navier–Stokes equations using the Smoothed Particle Hydrodynamics method. An appendix presents the validation of the numerical methodology through correlation of the numerical simulations with field data recorded during the 2011 Japan Earthquake and Tsunami. The methodology is then employed to characterize the ground shaking and tsunami loading patterns at the site of the container terminal of the Sines deep-water seaport in Portugal, when subjected to the historic 1755 Great Lisbon Earthquake and Tsunami plausible scenarios. For the site, the generated ground motion acceleration time series show peak accelerations exceeding Eurocode 8 design values. Tsunami flow depths and velocities were computed in horizontal and vertical directions and could be used in the assessment of the existing infrastructure or the design of the future expansion of the port.

Design of Vertical Evacuation Building at Painan City Using Results From Tsunami Propagation Modeling

Fault under the Mentawai Islands has high potential to cause a large earthquake and triggering tsunami. Painan City, is located near the fault. With geographical condition on a bay surrounded by hills in the upstream area, a tsunami may cause a flow channeling effect and increase the inundation distance. An alternative of mitigation effort is to build a Vertical Evacuation Building (VEB) to help the community to reach a safe elevation within the evacuation time. Therefore, VEB should be designed to withstand tsunami impacts and to resist large earthquakes. This study conducts the design and analysis of the performance of multi-functional VEB structures at Painan City. The tsunami propagation simulation was carried out, and parameters obtained were used for structural design. Three VEB models were developed, i.e., (i) model with walls under tsunami and earthquake loads, (ii) model without walls under tsunami and earthquake loads, and (iii) model without walls under earthquake load only as the lateral load. Non-linear static pushover analyses were later conducted to evaluate the structural performances. The study revealed that debris force affects the most compared to other tsunami force components. Structural openings also affect the tsunami load received by the structure. Column moment force for models designed with tsunami load is greater than that of earthquake, while the difference is less significant for beam. The internal force differences occur along the tsunami inundated depth, thus influence the component design. From the pushover analysis, all models were found to meet the performance targets for earthquake.

SCOUR AMPLIFICATION CAUSED BY STRUCTURE PROXIMITY IN EXTREME FLOWS

Forensic engineering field surveys of recent tsunamis (Saatcioglu et al. 2005, Chock et al. 2013) highlighted the importance of scour-related damage to structures located in coastal communities. To date, only a limited number of studies have investigated the interaction of extreme hydrodynamic flows and groups of structures, and none have studied the scour around multiple structures interacting with each other. One field example discussed by Yeh et al. (2013) documented flow concentration in between two tsunami-resistant buildings, leading to a deep scour hole between them and infrastructure failures onshore of the gap between the two buildings. This field example shows that multiple buildings, often crammed, lead to complex flow-structure interactions, leading to flow and scour either amplification or reduction depending on the relative position of the buildings. Nouri et al. (2010) and Thomas et al. (2015) investigated the flow velocity amplification caused by structures proximity, which concentrated the flow onto a downstream monitored structure. Their results informed the ASCE7 Ch.6 “Tsunami Loads and Effect” standard on flow velocity amplification caused by nearby structures. However, in this standard, there is currently no link between flow velocity amplification factors and their effects on scour around structures.

TSUNAMI WAVE LOADING ON A STRUCTURAL ARRAY PARTIALLY SHELTERED BY A SEAWALL

In recent years tsunamis have been recognized as one of the most catastrophic natural disasters in the world, highlighted by the 2004 Indian Ocean tsunami and the 2011 Tohoku earthquake and tsunami. These countries affected by tsunamis like Indonesia, Thailand and Japan usually arm their coast with sea walls to provide protection for coastal urban regions; however, surveys have found during both tsunami events, several sections of breached sea walls had led to extensive damage in those coastal regions (Dalrymple and Kriebel, 2005; Sato, 2015). Previous studies have examined the sheltering effect by macroroughness to individual structures, but limited knowledge is available on the sheltering and flow concentration effect by a partially standing wall to a field of structural array. The result from this experiment will serve to provide a better understanding on the tsunami loading variation induced by different length of partial seawalls, and help prepare more accurate hazard maps for tsunami events.

TSUNAMI RUN-UP CONSIDERING TIME VARIATION OF DENSITY OF INUNDATION WATER

Aiming for the advancement of tsunami load, historical and/or prospective tsunami scale evaluations, practical empirical formulas for evaluating friction factor K of inundation flow and density ρ of inundation water over a movable bed, which can be applied to a tsunami run-up theory, are proposed using experimental data whose amount (range) is increased (expanded) by carrying out additional experiments on ρ and run-up of inundation flow with sediment, and verification data of the above theory under a uniformly sloping movable bed condition are provided. Series solutions with a higher universality to the run-up of tsunami inundation flow with sediment over a uniformly sloping movable bed, in which both K and ρ depend on time, are derived under the conditions depending on an incident bore height h1 at shoreline (or an initial stored water depth), bed slope i, median particle diameter d50 of initial bed material, and examples of the solutions are shown. The solutions are applicable to the case that ρ is independent on time, i.e., the case of inundation flow without sediment over a movable bed or fixed bed. Including the case of inundation flow without sediment, validity of one of the solutions is also verified through a comparison with the verification data on run-up distance.

Analisis Struktur Beton Bertulang Tahan Gempa Untuk Berbagai Variasi Tinggi Bangunan

Indonesia is a country prone to earthquakes because it is located at the confluence of the Pacific and Trans-Asiatic Circum. Padang is included in the 5-6 earthquake area (KDS E & F), which is an area that has the potential for an earthquake accompanied by the possibility of a tsunami., comfortable and safe against the dangers of an earthquake or tsunami. The most influential factor in the planning of high-rise building structures is the strength of the building structure itself, where this factor is closely related to the safety and resilience of the building in holding and accommodating the loads acting on the structure. Instability in the structure is a basic thing that must be avoided and considered for various types of building heights. An unstable structure when subjected to loads causes the structure to experience a greater deformation than a stable structure. One way that can be done to make the structure more stable is to combine the structure with Shear Walls. Shear wall systems can be used to withstand vertical forces such as gravity loads and horizontal/lateral forces such as earthquake and tsunami loads, thereby preventing excessive swaying of the structure. The use of shear walls is also intended so that when an earthquake and tsunami occurs, the lateral forces that affect the structure are not only resisted by the beam and column elements in the structure but are also resisted by the shear wall system. because the placement of the shear walls that are not appropriate causes the shear forces that occur in the columns and beams to be greater. The research object is multi-storey reinforced concrete buildings with variations in height of 5, 7, 10, 15 and 20 floors. Buildings 5, 7 and 10 floors are designed with an open frame system, while buildings with floors 7, 10, 15 and 20 are designed with a double system, namely open portals and shear walls as lateral load resisters. Open portals use a Special Moment Resisting Frame System (SRPMK) design, while shear walls use a Special Structural Wall System (SDSK) design. The calculated structural loads are dead loads, live loads, superimposed dead loads and earthquake loads. Building location in the city of Padang with moderate soil conditions. The strength and stiffness of structures with shear walls are higher than those without shear walls

Developing a Resilience Index for the Pile-Supported Piers of the Port of Batangas under Tsunami Load

The roll-on/roll-off (ro-ro) transport system, which plays a huge role in the transportation and economy of the Philippines, mainly uses piers to provide smooth berthing of ships. However, its structural configuration attracts different hazards causing damage, particularly to piles. Tsunamis produce devastating wave forces. This may heavily result in discontinuity of the whole port operation as there will be no available berthing structure for ships. Hence, this study was conducted to determine the structural resilience of the pile-supported piers of the Port of Batangas against tsunami loads at different variations of wave height and water depth. Structural software was used to model the piers and incorporate calculated tsunami drag forces. Furthermore, pushover analysis was performed to produce the base shear versus displacement curves needed for the calculation of the robustness index. The rapidity index, on one hand, is based on an interview with the Philippine Ports Authority - Port Management Office (PPA-PMO) of Batangas resulting in recovery rates for demolition works and pile replacement. Combining these indices using the concept of resilience triangle, values of the resilience index ranging from 0.0 to 1.0 were calculated at both longitudinal and transverse directions. As a result, the piers were categorized as highly resilient in almost 50% of the tsunami load cases. It proved that the pier with existing batter piles exhibits higher resilience than the other which is only supported by vertical piles.

Numerical Study of Tsunami Force on Superstructure of Offshore Rigid Frame Box Girder Bridge

Offshore bridges need to bear complex wave and current loads and face the threat of extreme loads such as tsunamis. Potential tsunamis will have disastrous effects on coastal areas. Compared with conventional beam bridges, there are few studies on rigid frame box girder bridges. In this paper, based on a continuous rigid frame box girder bridge in the offshore area, the parameters of tsunami impact force are analyzed. First, based on Stoke theory and water level in the storage area, the water level in the static water area and quasi stable area in the dam break wave working conditions are obtained, and 12 kinds of dam break wave working conditions are preliminarily proposed to be used for the background bridge. Then, according to the determined simulation working conditions, the box girder dam break impact numerical model is simulated. According to the calculated results, the stress characteristics of the box girder under the tsunami impact are described in the way of time history stage division, and on this basis, The stress mechanism is analyzed from the whole level and local level. The results show that on the whole level, the variation of horizontal force and vertical force with time can correspond to the variation of dam break flow around the box girder. At the local level, the horizontal wall boundary bears the vertical force, the vertical wall boundary bears the horizontal force, and the inclined wall boundary bears both the horizontal force and the vertical force. In addition, negative pressure is the cause of suction on the wall boundary. It provides a reference for the calculation and analysis of tsunami load of offshore rigid frame box girder bridges, the identification of bridge failure modes and the formulation of protective measures.

Development of Fragility Curves for Reinforced-Concrete Building with Masonry Infilled Wall under Tsunami

A tsunami is a natural disaster that destroys structures and kills many lives in many countries in the world. A risk assessment of the building under a tsunami loading is thus essential to evaluate the damage and minimize potential loss. A crucial tool in risk assessment is the fragility curve. Most building fragility curves for tsunami force were developed using survey building damaged data. This research proposed a method for developing fragility curves under tsunami loading based on the analytical building model data. In the development, the generic building was a one-story reinforced-concrete building with masonry-infilled walls constructed from the structural index, popularly built as residential buildings along the west coast of southern Thailand. Three damage levels were investigated: damage in masonry infill walls, damage in primary structures, and collapses. The masonry infill wall was modeled using multisprings to represent the load-bearing behavior due to tsunami with a hydrodynamic pattern. The fragility curves were developed using the maximum likelihood method and considering the uncertainty due to masonry infill wall type, tsunami flow direction, and tsunami flow velocity. The developed fragility curve agrees well with the empirical tsunami fragility curve of a one-story reinforced-concrete building damage data in Thailand from the 2004 Tsunami. The developed fragility functions could be adopted for assessing tsunami risk assessment and disaster mitigation for similar structures against different tsunami scenarios in the future.

Strengthening System Effects on the Out-Of-Plane Mechanisms Activation of Masonry Walls under Tsunami Loads

The vulnerability of masonry structures against tsunami loads is a highly debated topic in the research community due to the impact in the risk evaluation. The main aim of this paper is to examine the structural response of masonry walls against tsunami loads in terms of out-of-plane local mechanism activation. Furthermore, a critical discussion is proposed about the influence of strengthening system parameters on the out-of-plane response of the masonry wall. Results of parametric analyses are shown in dimensionless form to analyse the effects of main parameters, both for masonry walls and tsunami waves, on the structural response. The analyses results are the bases to design strengthening systems with fiber-reinforced composite materials in order to reduce the vulnerability of masonry structures under tsunami loads.

Large-scale experiments on tsunami inundation and overtopping forces at vertical sea walls

Tsunami are very long gravity waves that may cause significant damage to coastal sea walls. The majority of relevant design codes and research papers that describe methods for predicting tsunami loads on coastal walls consider the scenario of transitory force from a bore-led wave. This does not relate to tsunami that do not form bore waves. Bore fronts generally cause short term spikes in force, which may have little effect on the vulnerability of massive structures. Post disaster accounts suggest that most coastal walls show damage that implies failure modes that occur over moderate to long durations. Therefore it is likely that the bore front assumption gives an overly conservative prediction of maximum force, and may not capture the full timescale of tsunami loading. This paper uses a pneumatic tsunami generation facility to determine the force loading on two vertical coastal sea walls during tsunami inundation. Two sea-wall models, 0.15 and 0.25 m high, with crown widths of 0.1 m (7.5 and 12.5 m at a nominal prototype scale of 1:50) are tested. It is shown that bore fronts only occur for short period waves over the bathymetry tested. Bore fronts cause a very short period spike in force, which is followed by a transitory force approximated by the hydrostatic pressure equation. The loading of tsunami length waves of periods ≥ 40 s (280 s prototype at 1:50 scale), which do not break is not greater than 1.2 times the hydrostatic force. Overtopping volume is positively correlated to the time duration of positive upstream head over the crest, rather than its maximum value. Overtopping causes a small increase in the horizontal load due to the addition of a drag and momentum load. The magnitude and time of these effects are small and short-lived in comparison to the hydrostatic load. The results compare well with available equations based on hydrostatic force and the engineer may apply a desired multiplying coefficient of a factor of at least 1.2 to account for any added pressure and momentum, and the factor of safety intended. • Tsunami loads on vertical walls are no greater than 1.2 times the theoretical hydrostatic load. • Only shorter wave periods break and form bores; longer tsunami-length waves do not break. • Tsunami overtopping volume is related to the duration of positive head over the crest. • Tsunami overtopping applies a relatively small (against the hydrostatic load) additional horizontal force.

The structural analysis of school buildings in West Pasaman as tsunami shelters

The shelter buildings of SDN 02 Sasak Ranah Pasisie and MTS Darul Hikmah Sikilang at West Pasaman were built in year 2010-2011, but until year 2021, the construction were not completed yet. To continue the construction of these shelters, the structural analysis is first carried out to know the existing condition of the buildings. The structural analysis is carried out in order to find out whether the shelter buildings is still feasible to resist the working loads. The calculation of the working loads using the new SNI 1726-2019, including tsunami loads. Data of concrete quality is taken using a hammer test and the reinforcing steel by conducting a tensile test from the reinforcement sample taken in the field. To find out the capacity of foundation, the DCP (Dutch Cone Penetrometer) testing is carried out to obtain the qc (conus) value and the depth of hard soil. Structural analysis using a computer program with a 3D building model. From structural analysis is found that all dimensions of element as well as reinforcement of flexure and shear of structural element such as columns and beams including foundation are able to resist the working loads in accordance with the new SNI 1726-2019.

Behavior of Building Structure Subject to Tsunami Load

This study aims to analyze of the structural behavior of two-story building under the combination of earthquake forces and tsunami hydrodynamic forces, with model variations included the percentage of wall’s opening and thickness. The 3-D modeling of two-story buildings were conducted in this study using software SAP 2000; the first model consisted of wall panels with the percentage of openings of 0% (PD0), 25% (PD25), 35% (PD35), and 50% (PD50), while the second model included buildings with 150 mm and 250 mm wall thickness. In addition, the hydrodynamic force predicted by numerical simulations based on Smoothed Particle Hydrodynamic (SPH) was compared to that of predicted by semi-empirical design equations. The results of the wall panel modeling show that the greater the percentage of wall’s opening, the smaller the hydrodynamic load that can be carried out by the structure and hence, the lesser the stresses on the wall. The increase of building’s wall thickness from 150 mm to 250 mm under the combination of earthquake and tsunami loads decreased the stress on walls, moments and transverse forces. Conversely, the tensile and shear stresses on the walls were increased due to the combination of tsunami loads. The comparison of hydrodynamic force shows that the maximum force predicted by SPH was generally higher to that of predicted by the semi-empirical design equations.

STUDY OF TSUNAMI LOADS ON TWO STRUCTURES WITH RECTANGULAR SECTIONS

STUDY OF TSUNAMI LOADS ON TWO STRUCTURES WITH RECTANGULAR SECTIONS

Performance of an RC building under seismic and tsunami actions in sequence via nonlinear dynamic analysis including soil-structure interaction

This research presents a methodology to study the behavior of buildings subjected to seismic and tsunami loading in sequence, considering soil structure interaction effects through a complete dynamic analysis. The case-study building is an RC frame, which is assumed to be located in a coastal city in Chile, and built on sandy soil. A 3D Soil-Structure Interaction (SSI) model, including the non-linear behavior of both the structure and the soil using finite element method (FEM) was presented. Synthetic seismic ground motion records and tsunami inundation time histories were generated, consistent with the same earthquake source. Building performance was first assessed considering the SSI model for each hazard separately and compared to a Fixed Base (FB) model. Then, the SSI model was subjected to seismic and tsunami loading in sequence. Engineering Demand Parameters (EDPs) of roof displacement, interstory drift ratio (IDR) and reinforcement strain in beams and columns were analyzed. These EDPs presented a larger response to the tsunami when the response to the previous earthquake was larger. Finally, two vertical evacuation building scenarios were studied: the location of the refugees and the effect of an aftershock occurring simultaneously with the tsunami inundation. Results showed that the location of the refugees did not generate significant differences in the building response, and the aftershock increased the response only when it coincided with the maximum tsunami force.