In 90% a tsunami is caused by a submarine earthquake.
From the sciencedaily.com
This is particularly common in Asia, where many submarine links cross submarine earthquake zones such as the Pacific Ring of Fire.
From the en.wikipedia.org
When the rough spots can no longer hold, the sudden release of the built-up motion releases, and the sudden movement under the sea floor causes a submarine earthquake.
From the en.wikipedia.org
The eruption has no direct connection with the submarine earthquake of 26 October 2010, which released a devastating tsunami on the Indonesian islands of Mentawai.
From the en.wikipedia.org
Sumatra-Andaman earthquake and Asian Tsunami was a result of the pressure at this zone causing a submarine earthquake which then resulted in a huge Tsunami.
From the en.wikipedia.org
Some tsunamis occur when an earthquake generates a submarine landslide, but that mechanism can be ruled out in many cases.
From the sciencedaily.com
Large waves produced by an earthquake or a submarine landslide can overrun nearby coastal areas in a matter of minutes.
From the en.wikipedia.org
The five basic steps are found equally well whether we are talking about an earthquake, a submarine using sonar to locate its foe, or a band playing in a rock concert.
From the en.wikipedia.org
Unfortunately, high rates of natural erosion in the region have long since wiped away the geological signs of the last earthquake along this submarine fault.