Tsunami Propagation Simulator
Click anywhere on the ocean to place an earthquake epicenter. Watch wave rings radiate outward and see estimated arrival times for 20 major coastal cities. Adjust magnitude and simulation speed to explore how ocean tsunamis travel thousands of kilometers in hours.
Click the map to place an earthquake epicenter
Click on the map to place an earthquake epicenter.
Estimated arrival times for 20 coastal cities will appear here.
Reference Guide
Tsunami Physics
Tsunamis are shallow-water waves because their wavelength (often hundreds of kilometers) is far greater than ocean depth. This means the wave speed depends only on water depth, not on the wave itself.
The speed formula is v = sqrt(g x d), where g is gravitational acceleration (9.81 m/s2) and d is water depth in meters. In 4,000 m deep ocean this gives about 713 km/h - faster than a commercial airplane.
As a tsunami approaches shore and depth decreases, the wave slows down but grows taller. This shoaling effect follows the relation h proportional to d raised to the power -1/4. A wave that is barely noticeable in open ocean can become a wall of water tens of meters tall at the coast.
Historical Tsunamis
The 2004 Indian Ocean tsunami (M9.1, Sumatra) killed over 230,000 people across 14 countries. Waves reached Sri Lanka in about 2 hours and Somalia in under 7 hours - both with devastating 10-30 m wave heights.
The 2011 Tohoku tsunami (M9.1, Japan) generated waves exceeding 40 m in some coastal bays, caused the Fukushima nuclear disaster, and was detected by sensors as far away as Chile and Norway.
The 1960 Valdivia earthquake (M9.5, Chile) remains the largest recorded earthquake. Its tsunami crossed the Pacific in about 15 hours, striking Hawaii with 10 m waves and Japan with 6 m waves roughly 22 hours after the quake.
Early Warning Systems
The Pacific Tsunami Warning Center (PTWC), established in 1949 in Hawaii, monitors seismic activity and issues alerts for the Pacific basin. A sister center for the Indian Ocean was created after the 2004 disaster.
DART buoys (Deep-ocean Assessment and Reporting of Tsunamis) are anchored to the seafloor and detect pressure changes from passing waves as small as 1 mm. Data is transmitted via satellite in near real time, giving emergency managers minutes to hours of warning.
Even with modern warning systems, local populations near the epicenter may have only minutes before the first wave arrives. Community education and vertical evacuation routes remain critical for nearby coastal areas.
Coastal Vulnerability
Not all coastlines face the same risk. The shape of the seabed and coastline geometry strongly influence wave height. Narrow bays and V-shaped inlets can funnel water and amplify waves dramatically - a process called resonance and runup.
Runup is the maximum vertical height the water reaches above sea level. In extreme cases (like the 1958 Lituya Bay landslide tsunami) runup exceeded 500 m on steep slopes, though typical ocean tsunamis produce runup of 1-30 m.
Natural barriers such as coral reefs, mangroves, and coastal wetlands can reduce wave energy by 50-90%. Their destruction through development and climate change is increasing coastal exposure to tsunami damage worldwide.