The prolonged drought in California, which took place between October 2011 to October 2015, made the Sierra Nevada mountain range grow by almost an inch, according to a new NASA study.
Researcher Donald Argus said the growth indicates that the solid Earth has a higher capacity to store water than what scientists previously thought.
The Earth’s Surface Starts To Rise In The Absence Of Water
The surface of the Earth falls when weighed down by water, and it starts to rise when the water is removed. The research team also observed that once Sierra got back rainfall and snow, the mountain started to shrink again and is currently down by 12 millimeters.
The scientists got the data for the study from 1,300 GPS stations installed as a part of the National Science Foundation’s Plate Boundary Observatory. They were positioned in western mountain ranges from 2006 to 2017.
The GPS Stations are highly sensitive and can monitor volcanoes, check on active fault lines, and measure subtle tectonic changes, as well as collect data continuously for nearly five times a second and also spot a change of just a few millimeters too.
The Sierras’ fractured rocks lost nearly 10.8 cubic miles of water, which is equal to 45 times the volume of water as Los Angeles consumes in a year. However, the water is inaccessible to humans.
"One of the major unknowns in mountain hydrology is what happens below the soil," said researcher Jay Famiglietti. "How much snowmelt percolates through fractured rock straight downward into the core of the mountain?"
Famiglietti hopes the research will help scientist to know more about water trapped within mountains, how the water table within mountain ranges look like, and if there is a massive volume of groundwater contained within mountains.
The Rise And The Fall Of Mountains
There are various reasons why mountains and other land formations grow or shrink. Generally, the Earth’s surface sags under water weight and gains back the lost height when the water is displaced by evaporation or drainage.
Low- and high-pressure weather systems, volcanic activity, and tectonic plate movement can also influence the surface uplift or depression, according to the research team. Apart from the natural reasons, human activity such as groundwater pumping can also have a significant impact.
At first, the study authors had thought the Sierra Nevadas had gained height due to extensive groundwater pumping and the nearby California Central Valley’s extensive groundwater pumping.
Calculations, however, showed that groundwater pumping could attribute to only 0.2 inches of the total inch of the mountain’s observed uplift, and tectonic shifts could contribute to less than half of it. The team found that the remaining two-thirds of an inch in the growth was caused by the elastic response of the Earth to water loss in the mountain.
