The Mariana Trench swallows far more seawater than anyone predicted

Mariana Trench swallows far more seawater.

It lies in the western Pacific, about 200 kilometres east of the Mariana Islands.

There, the Pacific plate slides under the Mariana plate.

As that plate sinks, it drags ocean water down with it.

Scientists knew plates could carry water down, but not how much.

Seawater seeps into cracks as the plate bends downward.

There, the water gets locked inside minerals like serpentine.

That wet rock reaches almost twenty miles beneath the seafloor.

Later, the released water melts the rock above, and fuels volcanoes across the Mariana Islands.

To measure it, researchers placed nineteen seismometers on the seafloor.

They listened to the trench for more than a year.

Waves move differently through wet rock, so the sensors could map the hidden water.

All told, four times more water sinks than scientists calculated.

Scientists believe most of it returns to the air when volcanoes erupt.

Yet more still goes down than seems to come back out.

So worldwide, deep water estimates may need to rise threefold.