The effects of vegetation coverage, topography and coastal orientation on the 2011 Tohoku-Oki (Japan) tsunami inundation investigated by satellite data

Abstract

We have studied the inland disastrous evidences of the tsunami triggered by the earthquake (M 9.0) occurred on March 11th, 2011 (at 05:46:23 UTC) offshore the coast of Honshu island (Japan). This large earthquake has been generated along the subduction plate boundary between the Pacific and the North America plates. The followed destructive tsunami caused casualties and severe damages along the coastline of most of Honshu Island. The dataset used in this work is composed of data in the visible spectral range, provided by ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) and Hyperion sensors, while for the microwave we have taken advantage of the active sensors such as Synthetics Aperture Radar (SAR). The large amount of data available from different sensors onboard of different satellite missions have allowed to sample the gradual tsunami inundation receding during the days soon after it occurred. Unsupervised and supervised algorithms have been applied for land cover classification purposes, identifying and mapping the extent of the effects caused by the tsunami on the different land cover classes present on the scene nearby the Sendai coast. The change classes, which have been identified, are in particular the stressed vegetation, the structural/house damage, the flooded areas, the debris, the sand deposits and boulders. The synoptic view, which is peculiar of remote sensing satellite data, DTM analysis and the information extracted from such a broad spectral range data have allowed an analysis of the tsunami characteristics phenomenon, such as the minimum inundation distance and the minimum run-up, respect to physical characters of the coastal area, such as topography, vegetation coverage and coastal orientation. This study would contribute to the definition of the susceptible level of the coastal region to get devastated by tsunami wave.