On March 11, 2011, a magnitude Mw 9.0 earthquake occurred off the coast of Japan's Tohoku region causing catastrophic damage and loss of life. The tsunami flow velocity analysis focused on two survivor videos recorded from building rooftops at Kesennuma Bay along Japan's Sanriku coast. A terrestrial laser scanner was deployed at the locations of the tsunami eyewitness video recordings. The tsunami current velocities through the Kesennuma Bay are determined in a four step process. The LiDAR point clouds are used to calibrate the camera fields of view in real world coordinates. The motion of the camera during recordings was determined. The video images were rectified with direct linear transformation. Finally a cross‐correlation based particle image velocimetry analysis was applied to the rectified video images to determine instantaneous tsunami flow velocity fields. The measured maximum tsunami height of 9 m in the Kesennuma Bay narrows were followed by maximum tsunami outflow currents of 11 m/s less than 10 minutes later.

Super typhoon Haiyan struck the Philippines on 8 November 2013, marking one of the strongest typhoons at landfall in recorded history. Extreme storm waves attacked the Pacific coast of Eastern Samar where the violent typhoon first made landfall. Our field survey confirmed that storm overwash heights of 6–14 m above mean sea level were distributed along the southeastern coast and extensive inundation occurred in some coastal villages in spite of natural protection by wide fringing reefs. A wave model based on Boussinesq‐type equations is constructed to simulate wave transformation over shallow fringing reefs and validated against existing laboratory data. Wave propagation and runup on the Eastern Samar coast are then reproduced using offshore boundary conditions based on a wave hindcast. The model results suggest that extreme waves on the shore are characterized as a superposition of the infragravity wave and sea‐swell components. The balance of the two components is strongly affected by the reef width and beach slope through wave breaking, frictional dissipation, reef‐flat resonances, and resonant runup amplification. Therefore, flood characteristics significantly differ from site to site due to a large variation of the two topographic parameters on the hilly coast. Strong coupling of infragravity waves and sea swells produces extreme runup on steep beaches fronted by narrow reefs, whereas the infragravity waves become dominant over wide reefs and they evolve into bores on steep beaches.

This paper presents data on block and boulder transport during Super Typhoon Haiyan along a 4.5km long, low (5-12m) cliffed coastline in Calicoan Island, Eastern Samar, Philippines. Wave runup exceeding 15.2m elevation drove thousands of limestone clasts, many of whichwith volumes up to ~83m 3strongly exceed maximum values stated in the literature to be possible from storms, up to ~280m inland. A few very large clasts (65-132m 3) were not transported by the waves. As a group, and along with transport reported in May et al. [2015] at a different location during Haiyan, these appear to be the largest blocks verified to have been transported by storm waves, and suggest that a re-evaluation of storm wave transport capability is necessary. Comparison of present results with a global database of storm boulder transport shows a masselevation envelope below which transport is observed and above which no transport observations exist. Extension of initiation of motion criteria to include non-rectangular cross-sections significantly reduced inferred velocities necessary for boulder transport during Haiyan, particularly for overturning boulders. Still, the potential range of velocities remained significant once coefficient uncertainty was considered. Lifting/joint-bounded velocity estimates at cliff edges were much larger than for other transport modes, and are difficult to reconcile: it is suggested that processes at cliff edges may be significantly more complex than can be accurately represented with these simple theories.

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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 1250004-1 Coast. Eng. J. 2012.54. Downloaded from www.worldscientific.com by UNIVERSITY OF CALIFORNIA @ SAN DIEGO on 06/04/15. For personal use only. T. Shimozono et al.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.

Analytical solutions are derived to describe two-dimensional wave evolution in converging bays. Three bay types of different cross-sections are studied: U-shaped, V-shaped and cusped bays. For these bays, the two-dimensional linear shallow water equations can be reduced to one-dimensional linear dispersive wave equations if the transverse flow acceleration inside them is assumed to be small. The derived solutions are characterized as the leading-order plane-wave solutions with higher-order corrections for two-dimensionality due to wave refraction. Wave amplitude longitudinally increases with different rates for the three bay types, whereas it exhibits weak parabolic variations in the transverse direction. Wave refraction significantly affects relatively short waves, contributing to wave energy transfer to the inner bay in a different manner depending on the bay type. The perturbation analysis of very high-order wave celerity suggests that the solutions are valid only when the ratio of the bay width to the wavelength is smaller than a certain limit that differs with bay type. Beyond the limit, the higher-order effect is no longer a minor correction, implying that wave behaviours become highly two-dimensional and possibly cause total reflection. The higher-order effect on the run-up height at the bay head is found to be small within the applicable range of the solution, and thus, the run-up formula neglecting the transverse flows has a wide validity. We also discuss the limitation of run-up height by wave breaking on the basis of a breaking criterion from previous studies.

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