Tsunami Inundation Zone Research Articles

Necessity and Feasibility of Medical Containers in Nankai Trough Mega Earthquake

Introduction:In Japan, there is an 80% probability that the Nankai Trough Mega Earthquake will occur within 30 years, and a tsunami of more than 30 meters is expected to hit the Pacific coast, killing more than 320,000 people and devastating many towns. This study clarifies the necessity and feasibility of a high-performance medical container developed by Showa to fill the gap in medical care during a large-scale disaster, especially after the sub-acute stage.Method:1) Simulation of the damage to disaster center hospitals in the event of the Nankai Trough Mega Earthquake.2) To clarify the feasibility of immediate response, a demonstration experiment was conducted by combining and installing ten units of medical containers.Results:1) Of the prefectures where the death toll from Nankai Trough Mega Earthquake is estimated to be 5,000 or more, 119 disaster center hospitals located in cities and towns with coastlines were examined to determine if they were in the tsunami inundation zone. The results showed that 44 hospitals, or about 37%, were inundated and their medical functions were likely to be paralyzed.2) Ten containers of medical treatment rooms, ICUs, CTs, power supplies, and oxygen could be assembled in seven days. This is by far the shortest time compared to the more than two months it takes for a temporary hospital.Conclusion:It is clear that medical containers can fill the void of medical care in the event of Nankai Trough Mega Earthquake.

Evaluation of hazard brochures using topic viewing durations: Application to tsunami evacuation brochures.

This study describes a novel method of assessing risk communication effectiveness by reporting an evaluation of a tsunami information brochure by 90 residents of three Pacific coast communities that are vulnerable to a Cascadia Subduction Zone earthquake and tsunami-Commencement Bay, Washington; Lincoln City, Oregon; and Eureka, California. Study participants viewed information that was presented in DynaSearch, an internet-based computer system that allowed them to view text boxes and tsunami inundation zone maps. DynaSearch recorded the number of times each text box or map was clicked and the length of time that it was viewed. This information viewing phase was followed by questionnaire pages assessing important aspects of tsunami hazard and sources of tsunami warnings. Participants gave the longest click durations to what to do in the emergency period during earthquake shaking and in its immediate aftermath before a tsunami arrives-topics that should be displayed prominently in tsunami brochures and emphasized in talks to community groups. The smallest adjusted click durations were associated with advance preparations for a tsunami-topics that can be posted on websites whose URLs are printed in the brochures.

An agent-based model of short-notice tsunami evacuation in Waikiki, Hawaii

Evacuation planning is an essential part of transportation resilience. It is necessary to understand transportation systems and human behavior to plan for safe evacuation. This study estimates populations exposed to harm, clearance times and fatalities for short-notice evacuation for a catastrophic tsunami event. An Agent-Based Model (ABM) is developed and tested for Waikiki, Hawaii, with three travel modes: pedestrian, bicycle, and motor vehicles. The modeled environment includes the road network, tsunami inundation zones, and building footprints with vertical and horizontal evacuation destinations. Significant loss of life (38,760 persons) is estimated to occur with a catastrophic short-notice tsunami event. A new bridge over the Ala Wai Canal will create an additional exit route that could save 13,860 lives. Shortening tsunami detection and alert times by half would save 4,510 lives over the baseline, do-nothing scenario. Vertical evacuation is most effective and is estimated to save 55,770 lives. In addition to the importance to evacuation planning, the research using ABM supports longer term investment in transportation imnprovements, mitigation and adaptation.

Evacuating Vulnerable People During a Tsunami Disaster in Japan: A Simulation Using Wheelchairs

Safe, rapid evacuation during natural disasters is particularly challenging for people who are vulnerable and/or need assistance. This study evaluated the feasibility of an evacuation route from a residential area to a designated destination for wheelchair-bound people and their caregivers. Thirteen individuals participated in an evacuation simulation in which they pushed wheelchairs carrying individuals from a start point to a designated destination along a specified route. The simulation was implemented on September 9, 2018, between 9:00 AM and noon. The weather was recorded hourly. Individuals in the wheelchairs were weighted to equal the average weight for Japanese men aged ≥65 years. The route comprised three sections: two were within the predicted tsunami inundation zone and one was on higher ground. The gradients, distances, and altitudes of the three sections were determined using official documentation. Participants were videotaped as they traversed the route, and their speeds and times recorded as the wheelchairs crossed from one section to the next. Immediately upon reaching the destination, participants completed a questionnaire assessing the physical effects of the activity. The route was 280.6 m long with a total vertical increase of 13.9 m. Mean total transit time was 3 min 25 s, and the mean time taken to evacuate the predicted tsunami inundation zone (at 210.2 m) was 2 min 15 s. All participants’ speeds were slowest in the third section, which had the steepest gradient (11.14%). Ten participants reported moderate difficulty, difficulty pushing, and sweating. Nine participants reported shortness of breath. The results support use of the evacuation destination during a predicted earthquake tsunami ≥8 m high at landfall.

Experimental investigation of the effects of contraction on tsunami-induced forces and pressures on a box section bridge

Many bridges that lie within possible tsunami inundation zones are critical links in transport networks. Some efforts have been made to determine the effects of tsunamis on bridges, but only a limited range of published design guidelines are available. Therefore, it is necessary to further investigate the effects of tsunamis on bridges. In the current study, physical modeling experiments were carried out to measure bore impact forces and pressures for various tsunami bore strengths on a bridge deck with different abutment types (wing wall and spill-through) and different opening and submergence ratios. The experiments were conducted in a wave flume with dimensions of 14 × 1.2 × 0.8 m (length × width × height), equipped with an automatic gate designed to generate a tsunami bore. The horizontal and vertical forces showed an increasing trend with increasing submergence ratio for both types of abutment. However, the horizontal force showed a decreasing trend as the opening ratio decreased, while the vertical force initially increased as the opening ratio decreased, until it reached a peak value, and then it started to decrease. The overall shapes of the results for both types of abutment are similar, with higher values for spill-through abutments due to their lower energy dissipation rates. Based on the experimental data, empirical equations are proposed for estimation of tsunami loads as a function of opening and submergence ratios.

Case study: mapping the tsunami-hazard zone in the Pasir Jambak sub-district, in Padang, Indonesia

A tsunami hazard is an adverse event that causes damage to properties and loss of life. The problem in assessing a tsunami risk zone for a small area is significant, as available tsunami inundation zone data does not give detailed information for tsunami inundation and run-up in every nested grid. Hence, this study aims to establish a tsunami risk map in the Pasir Jambak sub-district, Padang, Indonesia. The map was carried out in every nested grid point of the area and on a large scale (1:5,000). The TUNAMI N3 program was used for the simulation of the tsunami inundation. A tsunami assessment was made through simulations in nine scenarios of fault parameter data for Sipora block earthquakes. The result of the study provides a tsunami inundation map. Furthermore, this tsunami inundation map can be used for communities, local authorities, government, and others for many studies, and decision-makers can come up with mitigation plans for a small study area.

The near-miss of a tsunami and an emergency evacuation: the post-exposure effects on future emergency preparedness and evacuation intentions

In the early hours of January 23, 2018, residents of Port Alberni, British Columbia, Canada, awoke to the sounds of the community’s tsunami warning system, alerting them of the need to evacuate. While the emergency evacuation successfully occurred, the tsunami, fortunately, did not. This event has provided an exceptional opportunity to understand how residents perceive near-miss events and how an evacuation experience due to a tsunami threat influenced residents’ views towards emergency preparedness and future evacuation intentions. The results of our survey, completed by four-hundred fifty-seven households, reveal a partial let-down effect for those living within the tsunami inundation zone and a partial wake-up for those living outside the zone. For those within the risk region, no change in perceived risk was found post-event; however, households in the high-risk region indicated greater levels of worry or fear towards future evacuations compared to those outside the risk region. No differences were found in the number of households who had preparedness plans in place when compared by risk zones; however, those living within the tsunami inundation zone indicated higher levels of intention for creating an emergency plan post-event. Of importance, those who experienced difficulties in evacuating reported significantly lower intentions for future evacuation, higher levels of worry, and a stronger sense of disapproval towards the evacuation as compared to those who did not experience difficulties. Additional contributions of this paper include recommendations for officials responsible for initiating and managing an emergency evacuation.

Households’ Intended Evacuation Transportation Behavior in Response to Earthquake and Tsunami Hazard in a Cascadia Subduction Zone City

Earthquakes along the Cascadia subduction zone would generate a local tsunami that could arrive at coastlines within minutes. Few studies provide empirical evidence to understand the potential behaviors of local residents during this emergency. To fill this knowledge gap, this study examines residents’ perceptions and intended evacuation behaviors in response to an earthquake and tsunami, utilizing a survey sent to households in Seaside, OR. The results show that the majority of respondents can correctly identify whether their house is inside or outside a tsunami inundation zone. Older respondents are more likely to identify this correctly regardless of any previous disaster evacuation experience or community tenure. The majority of respondents (69%) say they would evacuate in the event of a tsunami. Factors influencing this choice include age, motor ability, access to transportation, and trust in infrastructure resiliency or traffic conditions. While the City of Seaside actively promotes evacuation by foot, 38% of respondents still state they would use a motor vehicle to evacuate. Females and older respondents are more likely to evacuate by foot. Respondents with both higher confidence in their knowledge of disaster evacuation and higher income are more likely to indicate less time needed to evacuate than others. Generally, respondents are more likely to lead rather than follow during an evacuation, especially respondents who report being more prepared for an evacuation and who have a higher perceived risk. This study showcases a unique effort at empirically analyzing human tsunami evacuation lead or follow choice behavior.

The future tsunami risk potential as a consequence of building development in Pangandaran Region, West Java, Indonesia

This research is aimed to analyze the potential risk of tsunami in the Pangandaran region, consist of Pangandaran beach and Batuhiu beach area based on the increasing number of buildings over the last 10 years after the 2006 tsunami. This study used a descriptive comparative method, i.e. by comparing the number of buildings in 2017 with the number of buildings before the 2006 tsunami event. It was derived from high resolution images for the year 2006 and the aerial photographs from Unmanned Aerial Vehicle (UAV) for the year 2017. The exposed buildings are then superimposed with potential tsunami inundation zones based on the scenario of the 2006 tsunami to estimate the tsunami risk. The potential loss caused by the potential tsunami was calculated by considering the number of buildings loss potential. Many new buildings have been built from 2006 to 2017. In 2017, the number of buildings in Pangandaran beach becomes more crowded (1052 buildings) than in the 2006 post-tsunami event (921 buildings). Most of them are used for hotels and some small shops. In Batuhiu beach, the distribution pattern of the building is parallel to the coast, following the existing road network. Based on the September 2006 satellite imagery, the number of buildings remained there were 47 buildings. After recovery, the number of buildings becomes 261 or more than 5 times additional buildings. The total amount of loss due to the potential tsunami in Pangandaran and Batuhiu can reach exceed 200 billion IDR. Several action plans can be proposed, especially for evacuation infrastructure and capacity improvement for tourist and residents.

Household risk perceptions and evacuation intentions in earthquake and tsunami in a Cascadia Subduction Zone

This study examines public risk perceptions and behavioral intentions in the event of a Cascadia Subduction Zone (CSZ) earthquake and local tsunami on the Oregon Coast. A household survey was conducted in Seaside, Oregon, a small coastal community located within the impact radius of the CSZ. This research analyzes how situational variables of hazard proximity, past experience, preparedness, perception of location relative to a tsunami inundation zone, knowledge of tsunamis, and demographic variables, along with psychological constructs of risk perceptions and self-efficacy, influence intended evacuation behaviors. Results show that risk perception and self-efficacy have a positive significant influence on the intended behaviors of immediate evacuation. In addition, physical preparedness, tsunami-relevant knowledge and location perception serve as significant predictors of immediate evacuation intentions. Being female is positively associated with pre-evacuation behavioral intentions, encompassing checking social media, collecting documents, and contacting loved ones. The results contribute to the emerging body of literature examining human decision-making processes in extreme events.

Validation of an agent-based building evacuation model with a school drill

An effective evacuation of buildings is critical to minimize casualties due to natural or anthropogenic hazards. Building evacuation models help in preparing for future events and shed light on possible shortcomings of current evacuation designs. However, such models are seldom compared or validated with real evacuations, which is a critical step in assessing their predictive capacities. This research focuses on the evacuation of a K-12 (kindergarten to 12th grade) school located within the tsunami inundation zone of Iquique, Chile. An agent-based evacuation model was developed to simulate the evacuation of approximately 1500 children and staff from the school during a global evacuation drill carried out for the entire city. The model simulates the motions of heterogeneous human agents, and the simulations were validated using video analysis of the real event. Resulting error estimations between predicted versus measured flow rates and evacuation times are 13.5% and 5.9%, respectively. The good agreement between the simulated and measured values can be attributed to the known distribution of students and staff at the start of the drill, and their known exposure to emergency preparedness protocols. However, the results presented herein show that this mathematical evacuation model can be used for logistical changes in the emergency planning.

Population vulnerability to tsunami hazards informed by previous and projected disasters: a case study of American Samoa

Population vulnerability from tsunamis is a function of the number and location of individuals in hazard zones and their ability to reach safety before wave arrival. Previous tsunami disasters can provide insight on likely evacuation behavior, but post-disaster assessments have not been used extensively in evacuation modeling. We demonstrate the utility of post-disaster assessments in pedestrian evacuation modeling for tsunami hazards and use the US territory of American Samoa as our case study. We model pedestrian travel times out of tsunami inundation zones recreated for the 2009 Mw 8.1 Samoa earthquake, as well as for a probable maximum tsunami zone for future threats. Modeling assumptions are guided by fatality trends and observations of 2009 evacuation behavior, including insights on departure delays, environmental cues, transportation mode, and demographic characteristics. Differences in actual fatalities from the 2009 disaster and modeled population vulnerability suggest that a single set of estimated travel times to safety does not fully characterize evacuation potential of a dispersed, at-risk population. Efforts to prepare coastal communities in American Samoa for future tsunamis may be challenging given substantial differences in wave characteristics and evacuation potential of the probable maximum hazard compared to the 2009 event.

Tsunami design procedures for engineered buildings: a critical review

Tsunamis have the potential to cause enormous loss of life and socio-economic impacts on coastal communities. Central to tsunami risk mitigation is the protection of critical infrastructure and evacuation-designated buildings, which are often necessarily located within tsunami inundation zones. As such, these must be designed to withstand and remain fully or partially operational after a tsunami. Guidance documents for tsunami design of buildings exist in the USA and Japan, including the recent release of the US ASCE 7 chapter 6 on tsunami loads and effects. This paper outlines the key engineering principles of tsunami design of buildings, summarises and compares how these principles are addressed by US and Japanese standards, and outlines considerations not yet covered.

Improved Risk Assessment of Tsunami Inundation Based on Geospatial and Local Knowledge for Sustainable Development

Tsunami events have extensive implications for sustainable development, due to the social, economic, and environmental impacts they can cause. Take into account the competence of geospatial and local knowledge; these sources are integrated to assess tsunami risk assessment by utilizing satellite imageries. The study area of Talcahuano experienced severe damages due to the 2010 Chile earthquake and tsunami. The geospatial information of the damaged areas was identified by processing the surface reflectance values between pre- and post-disaster images of the satellite optical and SAR data. The DEM data was also employed to delineate areas according to the inundation height data. Local information of tsunami inundation was generated through a DIG participatory mapping. Both types of inundation maps showed good agreement with the results of field surveys. Furthermore, a map of the potential tsunamiinundation zone was produced to aid integrated risk assessments in the area. The map showed areas with high, medium, and low inundation level adopted from the satellite images and the DIG map. Keywords: Tsunami Inundati Satellite Imageries, Optical and SAR Sensor, DIG, Disaster Risk Reduction

Hazard proximity and risk perception of tsunamis in coastal cities: Are people able to identify their risk?

Researchers have previously reported that hazard proximity can influence risk perception among individuals exposed to potential hazards. Understanding this relationship among coastline communities at risk of flood events caused by storms and/or tsunamis, is important because hazard proximity, should be recognized when planning and implementing preparation and mitigation actions against these events. Yet, we are not aware of studies that have examined this relationship among coastline inhabitants facing the risk of a tsunami. Consequently, the aim of this study was to examine the relationship between hazard proximity and perceived risk from tsunamis among coastline inhabitants. Participants were 487 residents of the coastal city of Iquique, Chile. They completed a survey during the spring of 2013 that assessed their perceived risk from several natural and non-natural hazards. We found that hazard proximity maintains a negative relationship with the perception of tsunami risk among coastline inhabitants. While this result confirms the general trend obtained in previous studies, this one is conclusive and significant. In contradiction with previous findings, we found that participants from the highest socioeconomic status reported the highest levels of risk perception. This finding can be explained by the fact that most participants from the highest socioeconomic status live closer to the coastline areas, so their risk perception reflects the place where they live, that is in a tsunami inundation zone. Once again, hazard proximity proved to be a determinant factor of risk perception. Our findings have important implications for the development of plans and programs for tsunami preparedness and mitigation. These indicate that individuals do use environmental cues to evaluate their own risk and can potentially make correct choices when having or not to evacuate. Also suggest that preparedness should incorporate how hazard proximity is recognized by individuals and communities at risk.

Quantification of the Debris Accumulation in Fire Spread Area of Tsunami Inundation Zone Using Aerial Photogrammetry

Quantification of the Debris Accumulation in Fire Spread Area of Tsunami Inundation Zone Using Aerial Photogrammetry

Response to the 2011 Great East Japan Earthquake and Tsunami disaster.

We revisited the lessons of the 2011 Great East Japan Earthquake Tsunami disaster specifically on the response and impact, and discussed the paradigm shift of Japan's tsunami disaster management policies and the perspectives for reconstruction. Revisiting the modern histories of Tohoku tsunami disasters and pre-2011 tsunami countermeasures, we clarified how Japan's coastal communities have prepared for tsunamis. The discussion mainly focuses on structural measures such as seawalls and breakwaters and non-structural measures of hazard map and evacuation. The responses to the 2011 event are discussed specifically on the tsunami warning system and efforts to identify the tsunami impacts. The nation-wide post-tsunami survey results shed light on the mechanisms of structural destruction, tsunami loads and structural vulnerability to inform structural rehabilitation measures and land-use planning. Remarkable paradigm shifts in designing coastal protection and disaster mitigation measures were introduced, leading with a new concept of potential tsunami levels: Prevention (Level 1) and Mitigation (Level 2) levels according to the level of 'protection'. The seawall is designed with reference to Level 1 tsunami scenario, while comprehensive disaster management measures should refer to Level 2 tsunami for protection of human lives and reducing potential losses and damage. Throughout the case study in Sendai city, the proposed reconstruction plan was evaluated from the tsunami engineering point of view to discuss how the post 2011 paradigm was implemented in coastal communities for future disaster mitigation. The analysis revealed that Sendai city's multiple protection measures for Level 2 tsunami will contribute to a substantial reduction of the tsunami inundation zone and potential losses, combined with an effective tsunami evacuation plan.

The impact of the 2011 Tohoku earthquake tsunami disaster and implications to the reconstruction

The authors conducted a comprehensive study to identify the impact of the 2011 Tohoku tsunami disaster and to understand the lessons towards the reconstruction of Tohoku to build tsunami-resilient community. First, the authors identified the extent of tsunami inundation zone by field measurement and satellite remote sensing. A specific index for optical satellite images was applied for the extraction of tsunami inland penetration calibrated with the ground truth data (field survey data). Second, an integrated investigation of field measurement and aerial photo and video inspections with spatial information sciences was performed to understand the hydrodynamic aspect of tsunami inland penetration with a form of tsunami flow velocity and hydrodynamic force, and the preliminary results lead to new understandings of structural vulnerability against the 2011 tsunami with a form of tsunami fragility curve and an implication for land use management and relocation planning to reconstruct resilient coastal communities.

三陸海岸ならびに仙台平野における東北地方太平洋沖地震に起因した津波堆積物中のヒ素ならびに重金属類の起源

A total of 129 samples of tsunami deposits were collected immediately after the 2011 off the Pacific coast of Tohoku Earthquake at 5 km intervals over the 250 km length of the tsunami inundation zone. They were analyzed for 10 major rock-forming elements, arsenic, and base metals (Cu, Zn, Pb, and Cd) with EDXRF. Statistical analysis indicates that the populations of arsenic and heavy metals—with the exception of Cd, which had values below the detection limit—comprise two log-normal distributions divided by a threshold value: 89 ppm Cu, 245 ppm Zn, 48 ppm Pb, and 21 ppm As. Spider diagrams of their anomalous values normalized by average marine sediments in Sendai bay indicate a characteristic pattern in each mineralization province. They are coincident to river sediment anomalies detected before the tsunami and are also compatible with the production of disused mines located in the background area. We conclude that almost all base metals and arsenic anomalies in the tsunami deposits distributed on the Sanriku coast and Sendai Plain by the 2011 off the Pacific coast of Tohoku Earthquake are affected by specific geological and mineralogical properties.

Response of reinforced concrete columns impacted by tsunami dispersed 20′ and 40′ shipping containers

One of the major issues associated with structures located in the tsunami inundation zone is impact of massive objects carried by the tsunami flow. Characterization of forces and assessment of damage to structures due to such impact loads are vital for the design of buildings used for tsunami evacuation purposes and other important structures located in inundation zones. In the present study, numerical investigation of reinforced concrete (RC) columns impacted by shipping containers dispersed by a tsunami is carried out. Two types of general purpose standard shipping containers which are widely used for maritime freight transport impacting on RC columns with square and circular sections are considered, using high-fidelity finite element models. A series of container-column impact analyses is carried out, and damage to the column is evaluated by means of a damage index characterized by degradation of axial load carrying capacity. This study shows that columns in low-rise RC buildings located in tsunami inundation zones can be severely damaged due to dispersed shipping containers. The peak impact force obtained in this study is used to propose equations for impact duration and effective contact stiffness that could be useful when revising existing design guidelines.