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Effect of tides and source location on nearshore tsunami‐induced currents
Author(s) -
Ayca Aykut,
Lynett Patrick J.
Publication year - 2016
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2016jc012435
Subject(s) - amplitude , current (fluid) , tsunami earthquake , geology , seismology , submarine pipeline , tsunami wave , event (particle physics) , directivity , tidal current , oceanography , physics , telecommunications , engineering , quantum mechanics , antenna (radio)
Here we present the results of a numerical modeling study that investigates how event‐maximum tsunami‐induced currents vary due to the dynamic effects of tides and wave directivity. First, analyses of tide‐tsunami interaction are presented in three harbors by coupling the tsunami with the tide, and allowing the initial tsunami wave to arrive at various tidal phases. We find that tsunami‐tide interaction can change the event‐maximum current speed experienced in a harbor by up to 25% for the events and harbors studied, and we note that this effect is highly site‐specific. Second, to evaluate the effect of wave directionality on event‐maximum currents, earthquakes sources were placed throughout the Pacific, with magnitudes tuned to create the same maximum near‐coast amplitude at the harbor of study. Our analysis also shows that, for the harbor and sources examined, the effect of offshore directionality and tsunami frequency content has a weak effect on the event‐maximum currents experienced in the harbor. The more important dependency of event‐maximum currents is the near‐harbor amplitude of the wave, indicating that event‐maximum currents in a harbor from a tsunami generated by a large far‐field earthquake may be reasonably well predicted with only information about the predicted local maximum tsunami amplitude. This study was motivated by the hope of constructing a basis for understanding the dynamic effects of tides and wave directivity on current‐based tsunami hazards in a coastal zone. The consideration of these aspects is crucial and yet challenging in the modeling of tsunami currents.