Interference effect on tsunami generation by segmented seafloor deformations. (1st February 2022)

• Record Type: Journal Article
• Authors: Shen, Yaxiong; Whittaker, Colin N.; Lane, Emily M.; Power, William; Melville, Bruce W.
• Is Part Of: Ocean engineering. Volume 245(2022)
• Publication Date: 2022-02-01
• Subjects: Tsunami -- Wave generation -- Seabed motion -- Reynolds-averaged Navier–Stokes equations -- Linearised water wave solution -- Active generation; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2021.110244
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: Most tsunamis are triggered by seismic events, involving an underwater earthquake with a sharp vertical displacement of the seafloor. Generally, seabed deformations are not unipolar, but instead bipolar or even more complex. To model tsunamis generated by segmented seafloor deformations, an analytical model and a numerical model including source kinematics are presented. Specifically, a parametric analysis, varying the number of segments and the relative sizes of each segment, is performed to investigate their influence on the wave generation process. Destructive interference is observed between the free surface waves generated by adjacent segments moving in opposite directions. The relatively large horizontal velocities compared to vertical velocities within the rotating flow generated in the case with two opposing segments correspond to relatively low wave amplitudes and the shift in the location of the largest wave. When the net uplift or subsidence volume is smaller, the associated destructive interference is more pronounced. In addition, a larger number of opposing segments produce a more complex velocity field within the tsunamigenic region, causing more destructive interference on the free surface. The role of destructive interference induced by segmented seabed deformations should be considered in assessing tsunami hazards caused by complex fault ruptures. Highlights: We use an analytical and a numerical model to study waves generated by segmented seabed motions. When adjacent segments move in opposing directions, the wave groups exhibit destructive interference. The destructive interference is most pronounced when the amounts of elevation and subsidence are equal. A larger number of segments cause a stronger destructive interference of waves. The effects of wave nonlinearity for the impulsive cases become less important with more segments.