A study of the seismic structure beneath the Mariana Trench by a team of researchers from Stony Brook University and Washington University indicates that about three or four times more water is dragged deep into the earth’s interior than previously thought. Their findings, published in Nature, give some new insight for scientists to re-evaluate the global water cycle and how water moves into and out of the earth’s interior.
Weisen Shen, PhD, an Assistant Professor of Geosciences at Stony Brook University, and whose work involved using a novel tool to transfer raw seismic records into images that the team could use to estimate water amounts, explains that the finding is important to understanding water cycling of the earth. He says that assessing large-scale, long-term tectonics contributes significantly to global water cycling, which has been difficult to quantify precisely.
To conduct the study, researchers listened to one year’s worth of Earth’s rumblings (from ambient noise to remote earthquakes) using a network of 19 ocean-bottom seismographs across the Mariana Trench, the deepest ocean trench in the world located near China and Japan in the western Pacific Ocean. They extracted the hidden information into images of the down-going Pacific plate near the trench – an imaging process similar to a CT scan.
The seismic images obtained show that the area of hydrated rock at the Mariana Trench extends almost 20 miles beneath the seafloor — much deeper than previously thought.
The amount of water that can be held in this block of hydrated rock is considerable.
For the Mariana Trench region alone, four times more water subducts than previously calculated. These features can be extrapolated to predict the conditions under other ocean trenches worldwide.
For more about the research and the findings, see this news release.
The research is sponsored in part by the National Science Foundation.