Tsunamis are most likely to occur in the Pacific and Indian Ocean regions. Tsunamis are most commonly formed from undersea earthquakes that result in a sudden rise or fall of the Earth's crust under the ocean.
The boundary region of the Pacific Ocean, known as the Ring of Fire, that includes the coasts of California, the Philippines, East Asia and East South America, are the most susceptible to tsunamis. This region experiences the most earthquakes, resulting in more tsunamis.
There are also two major subduction zones near Indonesia in the Indian Ocean that are also susceptible to an increased frequency of harmful tsunamis.