One of the most effective solutions to improve the stability of coastal structures is to construct a submerged breakwater in front of at-risk infrastructure.
Tsunami Hazard Mitigation Using a Submerged Breakwater. Lin  conducted numerical experiments to study solitary wave interactions with submerged structures.
This is quite reasonable because selection of appropriate dimension for the structure is directly related to an effective design of a submerged breakwater. Many engineers have been attracted to establishing effective design criteria for construction of a breakwater since it usually costs a lot of money.
Thus, relatively low structures could be served as high structures in highly nonlinear cases and this should be considered in designing a submerged breakwater against a tsunami.
"Coral reefs serve as natural, submerged breakwaters
that reduce flooding by breaking waves and reducing wave energy," said Michael Beck, lead scientist at The Nature Conservancy research and environmental group, and a professor at the University of California in Santa Cruz.
He added, "a less intrusive protection along parts of Alexandria's shoreline is submerged breakwaters
, which can reduce erosion behind breakwaters but cannot protect against flooding or sea level rise."