Understanding Tsunamis: From Seafloor Uplift to Coastal Flooding

What Tsunamis Are

Tsunamis are large ocean waves typically caused by underwater disturbances such as earthquakes, volcanic eruptions, or landslides. These waves can travel across entire oceans at speeds of up to 800 kilometers per hour and reach heights of over 30 meters when they approach the coast.

The term 'tsunami' comes from Japanese, meaning 'harbor wave,' reflecting how these massive waves often devastate coastal areas upon landfall.

How Tsunamis Form

Seafloor uplift or subsidence triggered by tectonic activity can displace a large volume of water, initiating the formation of a tsunami. The energy from this displacement is then transferred to waves that propagate across the ocean.

The speed at which these waves travel depends on the depth of the water: c = sqrt(g h), where g is the acceleration due to gravity and h is the water depth.

Wave Propagation and Flooding

As a tsunami approaches shallower waters near the coast, its speed decreases but its height increases. This process is governed by Green's law, which describes how wave energy transforms into kinetic energy as it moves from deep to shallow water.

Coastal flooding occurs when the waves exceed the elevation of the land or infrastructure, leading to inundation and potential destruction.

Modeling Tsunamis

The simulation uses a 2D nonlinear shallow-water solver with detailed bathymetry to model seafloor uplift and wave propagation. The solver accounts for wetting and drying, Manning friction, and ensures mass conservation.

By observing the eikonal travel-time map and virtual tide gauges, one can predict the arrival time and height of the tsunami at different locations.

Frequently asked questions

Try it live

Everything above runs in your browser — open Tsunami Simulator 3D: Seafloor Uplift, Shallow-Water Waves and Coastal Run-up and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.