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A numerical computation of the 2011 Tohoku earthquake tsunami was performed to identify fundamental features of the tsunami evolution along the coast of Hokkaido, Japan. Edge waves formed at multiple locations where the refracted tsunami focused, governing local surface oscillations and regional variations in tsunami height along the Pacific coast of Hokkaido. The computation reasonably reproduced the distribution of surveyed tsunami height as well as the time records of surface elevation recorded at ports in Hokkaido. The major features of the frequency spectrum for the 2011 Tohoku tsunami were identical to those for the 2003 Tokachi-oki earthquake tsunami; inherent local properties of surface oscillation caused by the passage of edge waves existed, determined by the local bathymetry. [ABSTRACT FROM AUTHOR]

Propagation and inundation characteristics of the 2011 Tohoku tsunami on the central Sanriku coast are investigated through field surveys and numerical simulations using offshore wave recordings as incident wave conditions. The numerical model successfully reproduces the extent of flood areas as well as the distribution of tsunami heights along the intricate coastline except for run-up of extreme heights over steep slopes. The survey and computed results suggest significant variations of tsunami heights along the coastline. Their positive dependency on topographic slopes implies that the incoming tsunami propagates in standing wave mode to precipitous sites while in progressive wave mode accompanied by wave breaking over gentle slopes. Temporal-spatial analysis of wave properties in different bays reveals that the inner bay topography provides a clear contrast to inundation characteristics. The impacting waves have extreme heights due to the funnel effect and local wave resonances causing highly transient flooding in narrow V-shaped bays whereas tsunami surges over longer periods across innermost shores of U-shaped bays to produce large horizontal velocities during both run-up and backwash phases. [ABSTRACT FROM AUTHOR]

The authors visually inspected the building damage caused by the 2011 Tohoku earthquake tsunami, using the pre and post-event aerial photos. First, we prepared the mosaic of post-tsunami aerial photos acquired by Geospatial Information Authority of Japan (GSI), and conducted the visual inspection of buildings damage to classify the damage. The damage classification results are compiled with building shape files on GIS for mapping the structural vulnerability in the tsunami inundation zone. Finally, we discussed the structural vulnerability in the tsunami affected area based on mapping results of building damage. [ABSTRACT FROM AUTHOR]

On March 11th, 2011, the Pacific coast of Japan was hit by a tsunami generated by the largest earthquake (M9.0) in the history of the country and causing a wide range of devastating damage. Using preliminary reported data from many sources, some topics such as tsunami fatality ratio and tsunami fragility curves for structural damage are discussed and compared with other countries. This paper aims to discuss the damage characteristics of this tsunami as well as its mechanism, as observed through field surveys conducted over the 4 months following the tsunami. The field survey covers 13 areas in the Miyagi prefecture from Kesennuma city in the northernmost region to Yamamoto town in the southernmost region. The arrival time of the first tsunami along the coastal areas in the Miyagi prefecture was confirmed by stopped clocks found during the survey. The damage mechanism of coastal structures such as breakwaters, seawalls, tsunami gates, and evacuation buildings was investigated and discussed. Damage characteristics for each area, i.e., urban areas, port, coastal structures, fisheries, and agricultural areas, were also summarized. The conclusions drawn from the data analysis suggest that experience and education (soft countermeasures) are important to reduce the loss of life, as shown for example in the Sanriku area. The field surveys indicate that wood and reinforced-concrete (RC) structures should be balanced to survive both earthquake and tsunami forces, and the structural design for buildings should be reconsidered after the example in Onagawa town. In addition, coastal structures for tsunami countermeasures (hard countermeasures) should be more properly designed for survival instead of becoming floating debris upon being overturned by a tsunami. The combination of both hard and soft measures is especially necessary for optimizing the outcomes following a great disaster. These recommendations should be taken into consideration in the reconstruction efforts for better tsunami countermeasures in the future. [ABSTRACT FROM AUTHOR]

At 14:46 local time on March 11, 2011, a magnitude 9.0 earthquake occurred off the coast of northeast Japan. This earthquake generated a tsunami that struck Japan as well as various locations around the Pacific Ocean. With the participation of about 300 researchers from throughout Japan, joint research groups conducted a tsunami survey along a 2,000 km stretch of the Japanese coast. More than 5,200 locations have been surveyed to date, generating the largest tsunami survey dataset in the world. The inundation height and run-up height were surveyed by laser, GPS, and other instruments, and the tidal correction has been accurately adjusted using a tidal database and a numerical simulation for Tohoku, an area where tide gauges were destroyed by the tsunami. Based on the survey dataset, the regional and local scale analyses were conducted to understand the basic characteristics of this event. Maximum run-up heights greater than 10 m are distributed along 500 km of coast in direct distance. The affected area of this event was several times larger than historically recorded in Tohoku. The mean inundation height in the southern Sanriku region is 10-15 m and there are several peaks of inundation along the coast from the northern to middle part of Sanriku. [ABSTRACT FROM AUTHOR]

On March 11, 2011, at 14:46 local time, a powerful earthquake occurred off the Sanriku coast of northeastern Japan. It was immediately apparent that this was the strongest earthquake on the historical record, and the resulting series of tsunami ravaged the Tohoku region. In Iwate Prefecture, the tsunami height generally exceeded the design tsunami level for safety, which had been determined on the basis of the 1896 Meiji-Sanriku tsunami, the 1933 Showa-Sanriku tsunami, and the 1960 Chile tsunami. As of January 10, the number of dead and missing in Iwate rose to 6,035. Over 24,000 buildings had been destroyed. After the 1933 Showa-Sanriku, disaster prevention facilities were built along the coast. However, many tsunami seawalls and water gates suffered enormous damage from the impact of the 2011 Tohoku Tsunami. This paper sketches out the characteristics and scope of the damage in the coastal areas of Iwate Prefecture, with a particular focus on the northern coast of Iwate. [ABSTRACT FROM AUTHOR]

The field survey results obtained by the team of authors in the north of Miyagi Prefecture between April 1 and 6, 2011 are summarized referring to a part of the survey results by other teams of the 2011 Tohoku Earthquake Tsunami Joint Survey Group. The inundation height above sea level was measured using a laser range finder with a reflection prism. The inundation height was generally larger at bay heads, as well as promontory tips, except several points, which were sheltered by a peninsula or had a tapering area. The tsunamis reached inland far away from the sea along valleys and rivers. Not only steel frame buildings but also many reinforced concrete buildings were collapsed in Onagawa Town. According to the numerical results, the first of tsunamis from the west coast and the second of tsunamis from the east coast should come together in Utatsusaki Peninsula, which is consistent with the interviews to survivors. [ABSTRACT FROM AUTHOR]

Japan was hit by the tsunami generated by the greatest earthquake in the history of Japan. The authors conducted the post-tsunami field survey in Miyagi prefecture immediately after the event to measure the inundation depth and investigate damaged buildings. Most of the buildings surveyed were wooden houses and could be classified into 4 damage levels. The primary data of inundation depth and damage levels obtained from the field survey were used to create the tsunami fragility curves, which described the degree of structural damage as a function of the hydrodynamic characteristics of tsunami inundation. The developed fragility curves show that damage with more than a 50% chance of occurring is classified as minor damage, moderate damage, major damage and complete damage when the tsunami inundation depth is between 2.5-3.0 m, 3.0-4.0 m and 4.0-4.5 m and greater than 4.5 m, respectively. By comparing the developed tsunami fragility curves, wooden houses in the studied area have higher structural performance than those obtained from historical events in other areas. The new curves suggest that wooden houses will be severely damaged if the inundation depth is greater than 3 m and collapse if the depth is greater than 4 m while wooden houses from historical data can resist only 1-2 m. Moreover, wooden walls in Japan reduce the overall failure of a structural member because a wooden wall is easier to destroy (compared to brick walls in Thailand and Indonesia) and allows the tsunami to pass through, which reduces the pressure at the attacking front of the tsunami. The fragility curves are very important for the loss estimation and reconstruction plans of the city; they are also crucial for reducing the disaster damage from a future tsunami. [ABSTRACT FROM AUTHOR]

No abstract received. [ABSTRACT FROM AUTHOR]