Deep(er) Water

Earth has two water cycles.

The "water cycle" we learned about in school?

It’s only the first of our two water cycles. It makes up the rivers, oceans, and the clouds, but it ain't the only water cycle. It is made up of water in liquid, vapor, and solid form.

Earth has a second, deeper water cycle. Made up of water under very high pressure. The second, deeper cycle shapes the crust; it moves continents and powers volcanoes.

This deep water moves at a slow pace, as it cycles through through the crust and the mantle. When it reaches the surface, water moves at a faster pace, evaporating into clouds, and precipitating into snow or rainfall, to make up the oceans and saturates the atmosphere.

When it is underneath the surface, water appears to accumulate far below the crust, in a “Mantle Transition Zone” that lies between 410 and 610 km deep, between Earth's upper and lower mantles. The mass of water that accumulates there is more than all the water in the first water cycle. The water is retained in the structure of hydrous minerals such as olivine.

The water is not just staying there, it is active.

Indeed, deep water may be one the main driving forces driving volcanism. It alters the strength and behavior of Earth’s mantle, lubricates deep fault zones, and even triggers magma generation beneath volcanoes.

Igneous Provinces

At the larger scale, a similar process, repeated across the Earth, may have led to the formation of the “flood basalt basins” that formed over the course of Earth’s history, such as the Siberian Traps that erupted about 252 million years ago.

At a smaller scale, an example is Mount Changbai/Paeku on the northern edge of the Korean peninsula, powered by a magma plume rising from the top of the mantle; it floats atop a large volume of water trapped, under extreme temperature and pressure, between a sinking slab of plate and the crus