Quantification of the Debris Accumulation in Fire Spread Area of Tsunami Inundation Zone Using Aerial Photogrammetry

Abstract

The purpose of this study is to quantify the pre-fire conditions of debris which contributed to fire spread in tsunami inundation zone after the 2011 Great East Japan Earthquake. In this paper, debris accumulation depth in the burned-out area of Nainowaki region, Kesennuma, Miyagi, was estimated based on aerial photogrammetry using two pieces of photographs which had been shot from aircraft the day before the fire. The aerial photogrammetry is able to produce a digital surface model (DSM) which is a continuous three-dimensional representation of a terrain surface including features above the ground, such as buildings. The debris accumulation depth was calculated as the difference of DSM and DEM. DEM is a digital elevation model which is a continuous three-dimensional representation of a terrain surface except features above the ground. As a result, the average, median, and 75 percentile of the depth in the burned-out area were respectively 1.6 m, 0.8 m, and 2.1 m.