Washington, March 23 (ANI): A 20 year-long study by scientists has yielded precise estimates of the interlocking tectonic plates that account for about 97 percent of Earth's surface.
The study was carried out by Rice University geoscientist Richard Gordon and collaborators Chuck DeMets of the University of Wisconsin-Madison and Donald Argus of NASA's Jet Propulsion Laboratory in Pasadena, California.
The 25 tectonic plates that form Earth's surface are rigid, but they are in constant motion because they float atop the planet's interior.
The plates constantly grind together and slide past one another.
When two plates crash into each other, they form mountain ranges like the Himalayas. When they slide past one another, they cause earthquakes like the one that struck Haiti this year.
"We live on a dynamic planet, and it's important to understand how the surface of the planet changes," said Gordon.
"The frequency and magnitude of earthquakes depend upon how the tectonic plates move. Understanding how plates move can help researchers understand surface processes like mountain-building and subsurface processes like mantle convection," he added.
The new model of Earth, dubbed "MORVEL" for "mid-ocean ridge velocities," was developed by Gordon and longtime collaborators DeMets and Argus.
"This model can be used to predict the movement of one plate relative to any other plate on the Earth's surface," said DeMets, the lead author of the MORVEL paper.
"Plate tectonics describes almost everything about how the Earth's surface moves and deforms, but it's remarkably simple in a mathematical way," he added.
About three-quarters of the MORVEL data come from Earth's mid-ocean ridges, undersea boundaries between tectonic plates.
At these ridges, new crust forms constantly as magma wells up from beneath the planet's surface while the plates spread apart.
To judge how fast the plates are spreading, the team uses data from scanners that look at the magnetic profile of the crust that's formed at mid-ocean ridges.
When Earth's magnetic field changes polarity, it leaves a magnetic mark in the crust that's akin to a tree ring.
These polarity changes occur at irregular intervals - the last being about 780,000 years ago.
By matching up the marks from the polarity shifts at different points along mid-ocean ridges worldwide, the team can judge how quickly new crust is being formed. (ANI)