Sim, S.Y. and Huang, Z., 2016. An experimental study of tsunami amplification by a coastal cliff.

There is a general lack of understanding of the effects of coastal cliffs or other complex topography features on tsunami run-ups and tsunami heights onshore. We experimentally investigated several factors that might influence the amplification of onshore tsunami heights in the presence of a coastal cliff through a set of wave flume tests. The cross-shore bed profile used in the experiment was modeled using a composite slope made of three sections, with the gentlest section onshore to replicate the beach. A structure with an adjustable foreslope was mounted onto the beach section to model a coastal cliff. From our experimental results, a critical angle of about 45° was identified: the amplification factor increased with the cliff slope for cliffs gentler than 45°, and cliffs steeper than 45° gave more or less constant amplification factors for a given wave condition. The largest amplification factor found in this study is about 2.8; if water splashing was considered, the amplification factor would be even larger.