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.

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Boulders numbering in the high hundreds/low thousands, and with masses up to ∼ 30 tonnes, were transported onshore by Super Typhoon Haiyan in Calicoan Island, Philippines to maximum ground elevations that could exceed 9 m and terminal positions up to ∼ 180 m inland. One-dimensional Boussinesq hindcasts of coastal boulder motion showed intermittent transport initiated at the fronts of infragravity swash bores. Transport distances were found to be highly sensitive to wave-height, enough so that observations of terminal positions may be a viable method of estimating rough paleostorm magnitudes. The large accelerations at bore fronts generated significant inertial forces, particularly for larger boulders, but drag forces had greater root-mean-square magnitudes in all simulations. Widely used relations to infer fluid velocities from boulder properties were tested using modeled boulders -inferred velocities at modeled terminal boulder positions were compared to maximum computed Boussinesq fluid velocities at these locations and found A. B. Kennedy et al.to be significantly lower. This underprediction of inferred velocities was greatest for smaller boulders that were strongly mobile. Inferred drag loads compared to modeled values were somewhat more accurate for large boulders when a Froude number of unity was assumed to estimate flow depths. Although these boulders were unequivocally transported by storm waves, their large sizes and distances traveled venture into what has been considered the tsunami range. Thus, care must be taken to interpret the provenance of coastal boulder fields with unknown origin for lower to mid-latitude regions.

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