What natural event is primarily responsible for causing tsunamis?

Tsunamis are primarily generated by underwater earthquakes or volcanic eruptions. When an earthquake occurs beneath the ocean floor, it displaces a substantial volume of water, causing waves to propagate outward in all directions. These waves can travel across entire ocean basins and can become extremely dangerous as they approach coastal areas, often increasing in height and intensity. Volcanic eruptions under the ocean can also lead to similar displacements of water, resulting in tsunami formation.

While landslides, heavy rain, and storm surges can contribute to flooding and other coastal hazards, they do not typically generate tsunamis in the same way that seismic activity does. Landslides can cause localized waves if they occur near shore, but they are much less common and less powerful than those created by underwater seismic events. Heavy rain can lead to increased water levels but does not directly cause tsunami waves. Storm surges are associated with the impact of storms, such as hurricanes, pushing water onto land but do not involve the sudden water displacement characteristic of tsunami generation.