The discovery, reported in Science Advances, shows a subduction zone actively breaking into pieces. Subduction zones form where one tectonic plate is forced beneath another and pushed deep into Earth. They are responsible for some of the planet's largest earthquakes, powerful volcanic eruptions, and long-term changes to continents and ocean basins.

Until now, however, scientists have had few opportunities to see clearly how one of these enormous systems reaches the end of its life.

Subduction is one of the main processes that continually reshapes Earth's surface. As an oceanic plate sinks beneath another plate, material from the crust is carried downward toward the mantle, the hot layer beneath Earth's crust.

These systems can remain active for millions of years, but they cannot continue indefinitely. Otherwise, continents would eventually pile into one another, oceans would disappear, and much of Earth's geological history would be erased.