  A plethora of studies in the past decade describe tsunami hazards and study
their evolution from the source to the target coastline, but mainly focus on
coastal inundation and maximum runup. Nonetheless, anecdotal reports from
eyewitnesses, photographs and videos suggest counterintuitive flow dynamics,
for example rapid initial acceleration when the wave first strikes the initial
shoreline. Further, the details of the flow field at or within tens of meters
of the shoreline are exquisitely important in determining damage to structures
and evacuation times. Based on a set of three-dimensional numerical simulations
using solitary waves as a model, we show the spatial-temporal distribution of
the flow momentum, kinetic energy and force during the breaking process. We
infer that the flow reaches its highest destructive capacity not when flow
momentum or kinetic energy reach their maxima, but when flow force reaches its.
This occurs in the initial shoreline environment, which needs to be considered
in nearshore structures design.
