de Lange, W. P., & Moon, V. G. (2016). Volcanic Generation of Tsunamis: Two New Zealand Palaeo-Events. In G. Lamarche, J. Mountjoy, S. Bull, T. Hubble, S. Krastel, E. Lane, … S. Woelz (Eds.), Volcanic Generation of Tsunamis: Two New Zealand Palaeo-Events (Vol. 41, pp. 559–567). Springer International Publishing Switzerland. https://doi.org/10.1007/978-3-319-20979-1_56
Permanent Research Commons link: https://hdl.handle.net/10289/11788
Rapid emplacement of a mass via pyroclastic flows, or edifice failure, generates volcanic tsunamis. Physical modelling demonstrates that the efficiency of tsuna-mi generation is influenced by the angle the mass enters the ocean. Efficiency de-creases with increasing slope angle from 20° to 60°, before increasing to a maxi-mum at 90°, which corresponds to a mass falling directly into the ocean without interacting with the slope (impact tsunami). Further, in the case of surging pyro-clastic flows or regressive failures, successive closely spaced events may generate larger tsunami waves than a single event of comparable volume. It is difficult to assess if physical model results are meaningful for real world tsu-nami events due to limited observational data. This paper compares numerical models developed from physical simulations with palaeotsunami deposits from two New Zealand palaeo-events – pyroclastic flows from Mt Tarawera and edi-fice failure at Whakaari (White Island) – which constrains numerical simulations of the source mechanisms. The Mt Tarawera event involved multiple pyroclastic flows entering a lake during the AD 1314±12 Kaharoa Eruption. The interaction of multiple closely spaced pyroclastic flows is necessary to generate the 6-7 m maximum wave height inferred from near source tsunami deposits. Tsunami de-posits in the Bay of Plenty, dated to 2962±52 BP, are consistent with edifice fail-ure at Whakaari. In this case a single event with a volume of 0.23 km3 is suffi-cient to account for the tsunami deposits. Hence, if the failure was regressive, the successive stages were sufficiently close together to be indistinguishable from a large single event.
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© 2016 Springer International Publishing Switzerland.This is the author's accepted version. The final publication is available at Springer via dx.doi.org/10.1007/978-3-319-20979-1_56