The energy that creates tsunamis originates from underwater volcanic eruptions, earthquakes, and underwater . Ocean Currents

Landslides

Gas Pockets

Submarines

What causes a tsunami?... A tsunami is a large ocean wave that is caused by sudden motion on the ocean floor. This sudden motion could be an earthquake, a powerful volcanic eruption, or an underwater landslide. The impact of a large meteorite could also cause a tsunami. Tsunamis travel across the open ocean at great speeds and build into large deadly waves in the shallow water of a shoreline.

Largely uneconomic because they provide little profit or food surplusi think so