Method for Estimating Collision Force of Driftwood Accompanying Tsunami Inundation Flow

A practical method for estimating maximum superposed force due to simultaneous or near-simultaneous collision of pieces of driftwood accompanying tsunami inundation flow and its probability of occurrence is presented by examining inundation flow velocity (congruent to collision velocity), acceleration distance within which the driftwood velocity becomes almost the same as inundation flow velocity, collision force, collision force duration, rise time from start to peak collision force, driftwood collision probability and by systematically integrating examination results.