Lets look at the causes in detail.
The first cause that generate tsunami is undersea earthquake. Over 80% of tsunami in the Pacific Ocean are thought to have been caused by undersea earthquakes. Australia is surrounded by 8,000 kilometres of active tectonic plate boundaries and most earthquakes and volcanic eruptions occur where these plates meet.
|Earthquake caused Tsunami|
Second cause is undersea landslides and land sliding into the sea. Undersea landslides and land sliding into the sea may cause localised tsunami. Undersea landslides occur when a large amount of sediment is dislodged from the seafloor, displacing a water column and potentially generating tsunami. Land sliding into the sea and usually caused by an earthquake and also cause destructive local tsunami.
|How Tsunami generate|
In addition, Tsunami also happens when an oceanic plate hits a continental plate and the plates press together and pressure builds. Eventually, the heavier the oceanic plate slips under the lighter continental plate and causes an earthquake. The earthquake lifts part of the ocean up and drops other parts down.What happens on the ocean floor is mirrored on the surface of the water above. Furthermore, the gravity acts fast to even out of water’s surface. The seismic energy created that big wave and it doesn’t just disappear. Waves start moving up to 600 miles per hour but people can’t see them.