Tsunami Events and Lessons Learned

Due to its geographical location and geology, Japan is a country susceptible to a large number of weather-related events and destructive forces such as typhoons and tsunamis, volcanic eruptions and earthquakes. The Tohoku Region has six prefectures including Iwate and Miyagi, having the latter a surface area of 7,285 km² with varied topography with mountainous areas and the Sanriku coastline with rich aquatic/marine and land ecosystems. As well as important economic sectors such as agriculture, fisheries, forestry, manufacturing, food processing and tourism amongst others.

In March, 2011 the Great East Japan Earthquake and Tsunami occurred with enormous environmental, economic and societal impacts heavily impacting the coastline as well as the economic and social milieu as cities and towns, industrial and agricultural facilities, farms, fishing grounds, ports, schools, hospitals, roads, and infrastructure in general were either severely damaged or washed away completely. In a period of 2 year since large efforts have been made by the local and central government as well as the society to start restoring the damage.

Although far from being exhaustive, the present paper provides an overall view of the situation towards restoration during this period in key sectors such as Agriculture and Forestry, Environment, Fisheries, and Urban Areas, including Debris Management in Miyagi prefecture and the Sanriku coastline.

The submarine groundwater discharge (SGD) transports a significant amount of various contaminants into the coastal zone especially in tsunami affected areas. An assessment of the impact of intruded pollutants in the coastal ecosystems requires understanding the fate of the pollutants and processes of their dispersal in ambient waters. In this paper, we proposed a methodology for SGD data collection and data assessment, using different methods, technology, techniques and instruments as well as the 3-D coupled ocean circulation/particle-tracking model for assessment and predicting the transport and dispersal of pollution-containing SGD into a coastal environment. Among the proposed methods to use for data collection and the SGD assessment primary attention was paid to geophysical, hydrologic, remote sensing and hydro-geologic measurements, using natural radiotracers, measurements by seepage meters and benthic chambers, biogeochemical and biological measurements. Also, several new modeling approaches were considered in particular those which use the particle-tracking model. The particle-tracking model takes currents and turbulent diffusivities predetermined by the ocean circulation model and uses the Lagrangian approach to predict the motion of individual droplets, the sum of which constitutes a contaminant plume which is the result of discharge of contaminant-rich submarine groundwater. Presently, we limited our simulations to elucidate the effect of tides on the SGD/nitrate plume formation. The model predicts behaviour of a nitrate plume, its shape and variation during a tidal cycle in the shallow waters. The model can be used to predict contamination of coastal waters with various pollutants incoming with SGD in the aftermath of a tsunami when impact of the latter on aquifers can be significant.

In conventional modeling of tsunami inundation, based on nonlinear shallow water theory in a finite-difference scheme, the effect of buildings and structures is represented by a bottom friction parameter rather than by three-dimensional (3D) building shapes. But large, strong buildings should offer direct protection against an incoming tsunami, like seawalls. In this study, therefore, we incorporated 3D building data obtained from lidar measurements in modeling the tsunami from the 2011 Tohoku earthquake at the port of Sendai, Miyagi Prefecture, Japan, and compared the results from conventional modeling based on a digital elevation model. In the model incorporating 3D building data, the maximum inundation height was greater than in the conventional model at the front of coastal buildings and structures and smaller behind them. High-velocity currents appeared in the corridors between these buildings, and the tsunami inundation area was smaller in the residential zone because of the obstacles that buildings presented to the tsunami. These results mean that solid buildings and structures have a significant influence on the propagation of tsunamis on land. The effects of the 3D shapes of buildings and structures should be further investigated for detailed tsunami hazard assessments in urban areas.

Erosion and deposition by the 2011 Tohoku-oki tsunami in the coastal areas of the Sendai Plain were numerically investigated using the tsunami sediment transport model (STM). The simulation suggested that much of the sediment deposited on land originated from the beach and dune, whereas the contribution from sea-bottom sediments was quite minor. Erosion observed at the backs of engineering structures such as reinforced concrete (RC) dikes was reproduced well in the simulation. Simulated deposition and erosion inside the nearby coastal forest and farmlands were generally consistent with the observed data. Further investigation of the model parameters and implementation of dynamic change in the roughness coefficient and destruction of the structures are required to simulate detailed local variability of erosion and deposition and of the thin sand layer in the inland areas.

Significant environmental and societal impacts have ensued from the tsunami events during the last decade particularly those of the Indian Ocean (2004) and Pacific Coast of Japan (2011). Ecosystem services provided by marine inter- and subtidal benthic macroinvertebrate assemblages are tied to the changes in physical, chemical, and hydrological short and long term alterations to their habitats. Globally, benthic macroinvertebrate assemblages can be categorized to examine ecosystems services provided by these highly productive coastal areas. In addition to ongoing coastal human activity related threats to these areas, the disturbances to these assemblages immediately after a Tsunami event are currently a focus of research. Quantifying the impacts across the subunit of macroinvertebrate benthos is a necessary function for proper assessment of impacts to ecosystem services provided by coastal zones. The current knowledge base and predicted recovery timeframes, in addition to the need for further investigation of long term environmental societal factors are important globally.

The recent catastrophic tsunamis show that it is now more than ever necessary to assess tsunami hazard for all coastal communities. In fact, facing the dangerous increase of population in low-lying coastal areas during the last decades directly linked to the reduction of the natural defences against sea assaults, including tsunamis, and considering the economy of most of the concerned countries, solutions should be found quickly to protect those populations and/or mitigate the hazard. In that way, recent studies and post-event field observations have highlighted the protective role played by coral reefs and the consequences of their destructions on the tsunami amplitudes. In this study previous results about the effect of fringing coral reef geometry on the tsunami amplitude are discussed using numerical modeling of nonlinear shallow water equations (NAMI-DANCE code). For this purpose, a set of different artificial Digital Elevation Models has been prepared in agreement with real bathymetric profiles and results of simulations are compared and discussed together with the conclusions obtained by the other authors.

Tsunami may strongly impact beach ecosystems. To assess its magnitude five beaches along the Sendai Bay, Japan, were studied 2 months after the 11th March 2011 Tohoku-oki tsunami with focus on their recovery and meiofauna assemblages within few weeks after the event. The beaches recovered and new meiofauna assemblages established, which were strongly correlated to sediment grain size. The new data and review of previous works suggest that for beach ecosystems tsunami plays a role of ecosystem disturbance, not a catastrophe.

The long-term effect of tsunami inundation on soil salinisation was assessed following the 2011 Tohoku-oki tsunami in two areas on the Sendai Plain, near Sendai airport in the Miyagi Prefecture and Matsukawa-ura near Soma in the Fukushima Prefecture. Data gathered over four sampling seasons 2, 5, 9 and 11 months after the tsunami near Sendai airport show that the salt content generally decreased with time. Concentrations were nevertheless higher in February 2012 than in October 2011, probably due to capillary action and evaporation following long periods with little precipitation in the winter, while the lower concentrations in October were attributed to dilution due to intense rainfall prior to the sampling period. In February 2012, the area with chloride concentrations over the guidelines for the establishment of rice seedlings still extended for nearly 1 km between 2.45 and 3.33 km inland. Chloride concentrations also reached the guideline values at the land surface 1.71 km inland. This corresponded to the limit of the area deemed not suitable for rice production by local rice farmers. However, recent observations revealed that rice crops were not only halted in 2011 but also in 2012, probably due to high salinisation of soil and/or surface and groundwater. Our study shows that soil salinisation was still recorded to nearly 15 cm depth in areas with fine-grained organic-rich soil ~2.5 km from the shoreline 11 months after the tsunami, and that water-leachable ions were preferentially retained in organic-rich muddy sediment and soil, reflecting the long-term impact of tsunami inundation. In Matsukawa-ura, salt crusts still covered the area flooded by the tsunami in February 2012 and both the soil and muddy tsunami deposit were characterised by high chloride and sulphate concentrations. The latter might also lead to sulphide toxicity. Remediation measures have been implemented in certain areas, but further research needs to be carried out to test the effectiveness of the measures being used to allow rice production to resume.

We propose a numerical method to estimate the local wave height and period of a tsunami from the distributions of boulders. The method was applied to boulders (<23 t) at Pakarang Cape, Thailand that were displaced from the reef slope onto the tidal bench by the 2004 Indian Ocean tsunami. They were deposited characteristically below the high-tide line, irrespective of size and no boulders were deposited on land. These features were used as the constraint of the calculation. We conducted over 10,000 cross-sectional calculations to satisfy above mentioned constraints, showing that the wave height and period at the shoreline were calculated to be 4–6 m and 18–37 min, respectively, which well concur with observed values. The input parameters for this calculation are the sizes and initial positions of boulders with seaward/landward limits, which are obtainable through the geological survey for historical and pre-historical tsunamis. This method is useful to estimate the local wave height and period of historical and pre-historical tsunamis from boulders reported throughout the world.

The Batu Feringgi area (N coast, Penang Island), with a high concentration of beach hotels, is critical to the tourist economy of Malaysia. Three large imbricated granite boulders were discovered on the NE end of the beach, at 5°28′51.77″N, 100°15′72″E. These boulders, dipping 45°–70° seaward, are shaped as tabular parallelepipeds with rounded corners, with maximum masses of 1.1–2.4 t, based on a density of 2.71 g/cm³. The boulder shapes were dictated by the presence of joints in the coastal outcrops, which represent an uplifted and exhumed tropically-weathered granite-tor landscape.

In order to produce imbrication of several boulders, the mode of transport has to be rolling/overturning, rather than by sliding or saltation. The hydrodynamic equations for the initiation of boulder transport used in this study are the modified Nott equations, from Nandasena et al. (Marine Geology 281:70–84, 2011). Calculations were made using slopes of 2°and 5°.

The results of the calculations indicate that the minimum velocities required to transport the boulders under free-rolling transport modes were 6.07 and 6.12 m/s for 2° and 5° slopes respectively. For joint-bounded boulders, the minimum velocities are 9.39 and 9.53 m/s for 2° and 5° slopes respectively. These velocities are higher than the maximum velocities experienced at this particular locality during the great 26 December 2004 Indian Ocean tsunami, the largest known tsunami in recorded history. Because this tsunami flooded the area but did not result in appreciable damage to infrastructure, it is concluded that the imbricated boulders on Batu Feringgi beach are the result of tropical storm activity in the past, rather than from recent or past tsunamis. The N coast of Penang is thus regarded as safe from the hazard of damaging tsunamis resulting from mega-earthquakes in the Sumatra-Andaman subduction zone, but the area is prone to tropical storm damage (with a return frequency of about 1 in 400 years), with wave velocities exceeding 6–9.5 m/s.

The 2011 Tohoku-oki Tsunami affected approximately 600 km of the northeastern coast of the Japanese Honshu Island, leaving traces of destruction on man-made buildings and depositing mud- to boulder-sized sediment. Our field observations at Aneyoshi along the Sanriku “ria” coast, where a maximum run-up height of 39.2 m was recorded, add to the limited number of studies of tsunami wave effects on natural landscapes. We found evidence for (1) tsunami wave erosion that exposed bare rock by stripping basal hillslopes of regolith and vegetation, including trees, (2) transport and deposition of coarse gravel, and (3) scour-hole generation around a large boulder and a large sea wall fragment. Computer simulations indicate that the highest first wave reaching the Aneyoshi coast may have been about 20 m high, that the combined duration of the first three waves was tens of minutes to 1 h, and that the maximum wave velocity on land reached over 10 m/s and probably exceeded 20 m/s in the lower, wide reach of the Aneyoshi valley. We hypothesize that hillsides along the Sanriku Coast have been stripped by erosion of numerous ancient tsunami events recurring at century or even decadal scales, since at least the mid-Holocene. The cumulative effects of tsunami erosion on the hillslopes and their long-term evolution are important potential topics for future studies.

Concatenated Hazards refers to situations where one extreme event precipitates one or more other extreme events. The exemplar is the tsunami and the resulting nuclear accident that occurred in Japan following the 11 March 2011 magnitude 9 earthquake.

Australia’s major natural hazards are hydro-meteorological in nature and have resulted in concatenated hazard events. An example is the 2011 Cyclone Yasi. The rainfall in the Australian tropics is due to the effects of the monsoonal wet season, augmented by the extra rainfall from the occasional tropical cyclone. Though tropical cyclones themselves can produce strong winds, storm surges, and floods – the combination of a particularly wet wet-season and a tropical cyclone can intensify the disaster and amplify the consequences. This was the situation on 3 February 2011 when Cyclone Yasi made landfall in North Queensland, following on a December-January period that had seen extensive flooding in Queensland as a result of a strong La Nina. The extra concatenation from Tropical Cyclone Yasi was the increase in Australian banana prices.

The predictive ocean–atmosphere model (POAMA) of the Centre for Australian Weather and Climate Research indicated in May 2010 that the wet season in Queensland would be extensive, with large amounts of rainfall. Tropical cyclone Yasi, though intense, had a well-behaved track and from 30 January was forecast to make landfall in Northern Queensland.

Model results indicate that the effects of climate change will be to decrease the numbers of tropical cyclones affecting Northern Australia and to increase the proportion of severe tropical cyclones affecting the region.

This paper presents an integrated probabilistic framework that deals with the industrial accidents and domino effects that may occur in an industrial plant. The particular case of tsunamis is detailed in the present paper: simplified models for the inundations depths and run-ups as well as their mechanical effects on industrial tanks.

The initial accident may be caused by severe service conditions in any of the tanks either under or at atmospheric pressure, or triggered by a natural hazard such as earthquake, tsunami or extreme floods for instance. This initial event generates, in general, a set of structural fragments, a fire ball, a blast wave as well as critical losses of containment (liquid and gas release and loss). The surrounding facilities may suffer serious damages and may also be a new source of accident and explosion generating afterwards a new sequence of structural fragments, fire ball, blast wave and confinement loss. The structural fragments, the blast wave form and the features of the fire ball can be described following database and feedback collected from past accidents.

The surrounding tanks might be under or at atmospheric pressure, and might be buried or not, or protected by physical barriers such as walls. The vulnerability of the potential targets should therefore be investigated in order to assess the risk of propagation of the accidents since cascading sequences of accidents, explosions and fires may take place within the industrial plant, giving rise to the domino effect that threatens any industrial plant.

The present research describes the risk of domino effect occurrence. The methodology is developed so that it can be operational and valid for any industrial site. It is supposed to be valid for a set of sizes, forms and kinds of tanks as well as a given geometric disposal on the industrial site. The interaction and the behavior of the targets affected or impacted by the first explosion effects should be described thanks to adequate simplified or sophisticated mechanical models: perforation and penetration of metal fragments when they impact surrounding tanks, as well as global failure such as overturning, buckling, excessive bending or shear effects, etc. The vulnerability analysis is detailed for the case of tanks under the mechanical effects generated by tsunamis.

A mega tsunami hit the Sendai Bay Coast on March 11, 2011, overtopped coastal levees and intruded into far inland while sweeping houses, people and others away. Eighty percent of the levees, which rimmed the coast to protect the land from storm surges together with the wind waves were broken in various degrees of damage by the tsunami. The national and local governments decided to rebuild the levees to be durable even for mega tsunamis. This requirement motivates us to find the destruction mechanism of the coastal levees. We conducted field investigations and collected the tsunami records, aerial photos and tsunami videos. Especially, the video taken from the helicopter “Michinokugo” which flew along the Sendai Coast to the south during the attack of the tsunami’s leading wave enables us to see the breaking process. Integrated analysis leads to two step mechanisms of the destruction: the first step of breaking the upper structure of the levees by the surging bore of the leading wave and the second step of expanding erosion by the return flow concentration.

The 2004 Indian Ocean tsunami was one of the world’s worst tsunamis and caused devastating damage in many Asian countries. Then, in 2011, Japan was hit by a tsunami that was generated by the greatest earthquake in the country’s history. This paper discusses the damage caused by these tsunamis and subsequent reconstruction. Introduced first are the experience gained and lessons learned for future tsunami mitigation, such as tsunami awareness, proper evacuation building and the memorial parks created in the countries affected by the 2004 tsunami (Indonesia, Sri Lanka and Thailand). Second, human casualties and building damage are discussed using fatality ratios and fragility curves, respectively. These analyses show that experience and awareness help reduce human casualties in the Sanriku area, and wooden houses damaged by the 2011 tsunami fared better than in previous historical events. The damage by the 2011 tsunami to structures designed to protect against tsunamis is summarized. Most of these structures could not withstand and protect from the tsunami because they were not designed for such a large tsunami as expecting of such great event. Finally, examples of ongoing reconstruction in Japan are introduced. Most reconstruction efforts were planned after considering the lessons learned from the tsunami’s impact, and the towns in question are now strengthening their disaster prevention-related plans to be better prepared for future tsunamis.

We introduce the concept of a new type of vertical evacuation shelter. It combines the function of pedestrian bridge and tsunami tower, which are then installed at intersection. The idea provides the ease of constructing and maintenance in addition to the loss of required land acquisition. We first evaluate the performance of pedestrian bridges during the 2011 tsunami in Japan by taking into account the exposure component in term of their position from the shoreline and the susceptibility component in term of the tsunami height around the bridge as the influencing parameters in determining damage probability. We developed fragility curves to show that pedestrian bridges lay on an area less than 500 m from the coastline (around 0.1 of the maximum inundation extent), or in the area where the tsunami flow depth are 1.5 of the height of the bridge’s deck have more than 50 % probability to be damaged by the tsunami. If the function of pedestrian bridge will be expanded into ‘Tsunami-deck’, the information about tsunami behavior at the intersection therefore becomes important. For that reason, we performed a set of numerical experiment of tsunami flow at the intersection to determine conditions that will allow the installation of tsunami-deck with a height similar to the average height of the existing pedestrian bridge. By doing so, we attempted to determine preliminary placement criteria for Tsunami-deck in order to ensure the safety of evacuee. The results gave an opportunity to have more distributed vertical evacuation shelter in flat and densely populated areas.

In plain areas prone to tsunami, finding a way to shelter and escape from the inundation becomes a difficult task for residents. The 2011 Great East Japan Tsunami has shown that the horizontal evacuation using cars can compromise the safety of people. Another alternative is the vertical evacuation. In many cases, not only the capacity of these shelters plays an important role, but the spatial distribution and the evacuee preference for the nearest shelter. Such preference and location creates a conflict between capacity offer and demand. In this paper, we used an agent based model to simulate the evacuation of pedestrians and cars in La Punta, Peru. Twenty designated buildings for vertical evacuation are available for sheltering and escape from tsunami. The stochastic simulation of population spatial distribution and their refuge preferences revealed the over demand of some shelters. Finally, a capacity-demand map was created to share results with local authorities as a first step for future countermeasures in the district.

Tsunamis persist long after the triggering geophysical events diminish. The Tohoku, Japan tsunami of March 11, 2011 was an extreme event that continued to disturb the Pacific Ocean for many days following its initiation. Historically Japan was considered a source of low tsunami wave energy for the US West Coast. However, damage in California from the last great Japan tsunami was second to that suffered during the 1964 Alaska earthquake. Computer animations of the catastrophic Japan tsunami and other recent significant tsunamis combined with source wavelet cross-correlations help to identify multiple paths of tsunami wave energy refracted and reflected by complex bathymetry across the Pacific Ocean basin. Using recent large tsunamigenic earthquakes we demonstrate that the long duration and damage suffered in the far field during the great 2011 Tohoku Japan tsunami was a result of several factors. Shallow water waveguides and continental margins act as tsunami lenses and mirrors to direct the wave energy to diverse locations around the ocean basin; directionality affected by islands and seamounts, large reflections off of South America and Oceania (New Guinea region), bathymetric features far and near the area of impact and shelf geometry may delay and further amplify the main tsunami energy. This contribution of Ocean basin scatterers can be estimated a-priori and can help define impact zones vs. shadow zones and duration of events. This has direct implications on the prediction of tsunami impacts because the US West Coast often appears to receive maximum wave heights much later than first wave arrivals from far field tsunamis.

California has established a Tsunami Policy Working Group to facilitate development of policy recommendations for tsunami hazard mitigation. The Tsunami Policy Working Group brings together government and industry specialists from diverse fields including tsunami, seismic, and flood hazards, local and regional planning, structural engineering, natural hazard policy, and coastal engineering. The group is acting on findings from two parallel efforts: The USGS SAFRR Tsunami Scenario project, a comprehensive impact analysis of a large credible tsunami originating from an M 9.1 earthquake in the Aleutian Islands Subduction Zone striking California’s coastline, and the State’s Tsunami Preparedness and Hazard Mitigation Program. The unique dual-track approach provides a comprehensive assessment of vulnerability and risk within which the policy group can identify gaps and issues in current tsunami hazard mitigation and risk reduction, make recommendations that will help eliminate these impediments, and provide advice that will assist development and implementation of effective tsunami hazard risk communication products to improve community resiliency.

Unexpected devastation of the Thai communities along the Andaman coast lines by the 2004 Sumatra tsunami have changed the Thai perception on the earthquake and tsunami disaster forever. This paper tells about the economic and social impacts of the 2004 tsunami that affected the Thai society and the lessons learned from these tragic incident. Since then, a large amount of money and effort have been invested in the tsunami research and development, earthquake and tsunami monitoring and warning systems and a large number of educational outreach to young generations. The proper tsunami and earthquake mitigations of the central government collaborated with local governments integrated with the people’s understandings of the nature of the earthquake and tsunami help increase the readiness of the Thai community for such disaster more than ever. Still, many issues remain to be resolved such as a lack of proper maintenance of the critical facilities for the earthquake and tsunami mitigation and inadequate research and development in earthquake and tsunami sciences in Thailand. It is very difficult to maintain the level of the awareness of the people about the great danger of the earthquake and tsunami and it is also a big challenge to increase the ability of the Thai society to have better critical scientific thinking about the natural disaster.

The paper presents a framework for assessing vulnerability in the context of tsunami early warning and evacuation at the local level. A case study in the city of Padang, Indonesia was given as a showcase on analysis of the vulnerability component of understanding and response to the early warning. Quantitative and qualitative analysis of household surveys as well as various semi-structured and non-structured interviews derive important parameters that should be considered in development an effective risk communication.

The 9.0-magnitude Great East Japan Earthquake and the subsequent tsunami on March 11 of 2011 was the most devastating natural disaster ever to have hit Japan in its recent history. The aftermath of this catastrophic event is extensive, including a negative impact on the world-wide effort in mitigating global warming by carbon emission reduction. Not only has the Fukushima nuclear crisis dramatically slowed down nuclear power development as a low carbon alternative energy, but also the infrastructure reconstruction would come with a heavy carbon footprint. According to the statistic data released by the Japanese government, over 396,067 buildings were fully or partially destroyed, and more than 728,583 partially damaged in this disaster. The building reconstruction must consume large amounts of construction materials and energy, which would inevitably increase the greenhouse gas (GHG) emission. In this study, we identify housing construction, land use conversion to settlement, and earthquake/tsunami wreck clearance as three major GHG emission related processes of post disaster building reconstruction. We derive a first order estimate of the embodied GHG emission of these three processes based on official statistic data of damages, the quantification of major resources required for typical Japanese residential building types, and the IPCC Guidelines for National Greenhouse Gas Inventories. The result shows that the post Great East Japan Earthquake housing reconstruction alone has at least an emission of 26.3 million tons CO₂ equivalent, or about 2.1 % of the total greenhouse gas emission of Japan in 2010.