An experimental study of tsunami deposit thickness trends

Experimental tsunami deposits were produced in a laboratory flume to determine how changes in grain size distribution, ponded water depth, bore height, and original bed topography effect deposit thickness. Tsunami and paleotsunami deposits in nature have been used to calculate flow depths and velocities, which improve risk assessments in tsunami prone areas. Physical experiments offer the potential to better quantify relations between tsunami bores and deposits under controlled conditions. We conducted ten different experiments in a 32-meter long flume varying grain size, bed topography, depth of ponded water, and bore height. For each run, sediment was placed in the upstream end of the flume. After each run, deposit thickness was measured along a longitudinal transect every 25 cm. We systematically varied ponded water depth to represent possible field cases from back-barrier lagoon to dry land. Resulting deposit morphologies suggest that deposits created in ponded water deeper than 15 cm in the flume show rapid thinning away from the sediment source while deposits over a dry bed show little to no change in deposit thickness.