Run-up from impact tsunami |
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| Authors: | D G Korycansky Patrick J Lynett |
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| Institution: | Department Earth and Planetary Sciences, University of California, Santa Cruz, CA 95064;, USA. E-mail: Coastal and Ocean Engineering Division, Department of Civil Engineering, Texas A&M University, College Station, TX 77843;, USA |
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| Abstract: | We report on calculations of the on-shore run-up of waves that might be generated by the impact of subkilometre asteroids into the deep ocean. The calculations were done with the COULWAVE code, which models the propagation and shore-interaction of non-linear moderate- to long-wavelength waves ( kh < π) using the extended Boussinesq approximation. We carried out run-up calculations for several different situations: (1) laboratory-scale monochromatic wave trains onto simple slopes; (2) 10–100 m monochromatic wave trains onto simple slopes; (3) 10–100 m monochromatic wave trains onto a compound slope representing a typical bathymetric profile of the Pacific coast of North America; (4) time-variable scaled trains generated by the collapse of an impact cavity in deep water onto simple slopes and (5) full-amplitude trains onto the Pacific coast profile. For the last case, we also investigated the effects of bottom friction on the run-up. For all cases, we compare our results with the so-called 'Irribaren scaling': The relative run-up R / H 0=ξ= s ( H 0/ L 0)?1/2 , where the run-up is R , H 0 is the deep-water waveheight, L 0 is the deep-water wavelength, s is the slope and ξ is a dimensionless quantity known as the Irribaren number. Our results suggest that Irribaren scaling breaks down for shallow slopes s ≤ 0.01 when ξ < 0.1 ? 0.2 , below which R / H 0 is approximately constant. This regime corresponds to steep waves and very shallow slopes, which are the most relevant for impact tsunami, but also the most difficult to access experimentally. |
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| Keywords: | hydrodynamics impact tsunami run-up wave propagation |
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