Post-event survey of locally concentrated disaster due to 2019 Typhoon Faxai along the western shore of Tokyo Bay, Japan

摘要

Typhoon Faxai caused severe damages along the western shore of Tokyo Bay, Japan in September 2019. Retaining a relatively small radius of maximum wind, Faxai passed across the center of Tokyo Bay and caused intensive wind and waves. While the sea level anomaly recorded at several tide gauge stations along Tokyo Bay were at most 1 m, and no significant surge-induced inundation was found, locally concentrated damages and wave-induced hazards were observed around Yokohama, on the middle-western shore of Tokyo Bay. The observed inundation height around Yokohama was TP (Tokyo Peil) 4.2 m on average, and the highest runup, TP 10.8 m, was observed at a small hill directly behind the seawall in Fukuura, Yokohama. The estimated wave overtopping directions at each location varied from the northeast to southeast, and no clear correlation was found between the wave overtopping directions and the extent of observed coastal hazards. Based on these findings and investigations of recorded data such as wind and waves, it was deduced that locally concentrated damages and hazards around the middle western shore of Tokyo Bay may be explained by the unique features of a relatively compact Faxai and the topographical characteristics of Tokyo Bay.