Researchers hope to use quakes to unlock secrets about Earth's crust

Dec 14, 2006

Over the past several decades, the United States Government established the Global Seismographic Network to monitor nuclear explosions worldwide. That network has also proven to be a crucial source of information for geologists and geophysicists like Drs. Stephen Gao and Kelly Liu, who are trying to unlock secrets about the earth’s crust.

In addition to recording nuclear tests and other large explosions, the 250 seismographic stations situated around the globe capture information about earthquake events, volcanic eruptions and other outbursts of energy. Gao and Liu, associate professors of geophysics at the University of Missouri-Rolla, receive the data in real time through a UMR computer capable of handling 6,000 gigabytes of information.

By studying how seismic waves propagate through the earth, Gao and Liu hope to answer some old questions about the nature of the earth’s crust. Most geoscientists believe 85 percent of the crust was formed in the earth’s first billion years. Others believe the crust has formed gradually over geologic time.

“We study the thickness, density, and composition of the crust below the 250 stations,” Gao says. “The larger the seismic event, the more data we get. By analyzing the seismic waves using sophisticated computer programs, we can peek into the earth’s interior and reveal its secrets.”

The early earth was a very volatile place and its interior was hotter, according to most geoscientists. The age of the crust observable today varies wildly from place to place due to plate tectonics and the constant activity below the earth’s surface. While the crust in Missouri might be 1.6 billion years old, it could be 3 billion years old in Minnesota or just half-a-billion years old in Japan. Gao and Liu are looking to see if there is a correlation between the age of the crust and changes in its composition and properties. Such changes, if revealed, could suggest that the processes that formed the crust during the early history of the earth were different from the processes we see today.

On average, the earth’s crust is about 22 miles thick. The crust floats, for lack of a better word, on top of the mantle. Over time, the crust moves and continental plates collide, creating areas of high seismic and volcanic activity.

“The modern view is that crust is generated by the subduction of plates into the earth’s mantle,” says Gao. “But the crust that is formed in subduction zones today could be located somewhere else in the world tomorrow, in geological terms.”

In subduction zones, one plate burrows under another into the hot mantle. The melting of rocks in the deep interior of the earth creates volcanoes above those zones, and the crust of the top plate is pushed up to form large mountain ranges like the Andes in South America. Plate subduction is also responsible for causing powerful earthquakes when the plates move.

What geoscientists like Gao and Liu are trying to find out is whether or not the processes of crust generation have stayed consistent throughout the planet’s volatile history.

Source: University of Missouri-Rolla

Explore further: Invisible helpers of the sea: Marine bacteria boost growth of tiny ocean algae

Related Stories

South American parrot in trouble: researchers

3 hours ago

A South American parrot with a wine-colored chest is in deep trouble, with its population down to some 3,000 and a habitat reduced to a speck of what it once was, researchers said Tuesday.

Recommended for you

The Arctic: Interglacial period with a break

41 minutes ago

Scientists at the Goethe University Frankfurt and at the Senckenberg Biodiversity and Climate Research Centre working together with their Canadian counterparts, have reconstructed the climatic development ...

Building collapse during earthquake aftershocks

54 minutes ago

Earthquakes kill, but their aftershocks can cause the rapid collapse of buildings left standing in the aftermath of the initial quake. Research published in the International Journal of Reliability and Sa ...

Large igneous provinces associated with mid-ocean ridges

3 hours ago

Lip reading normally involves deciphering speech patterns, movements, gestures and expressions just by watching a person speak. Planet Earth has LIPS, too - they are an acronym for large igneous provinces, ...

Volcanic ash proves inefficient cloud ice maker

4 hours ago

When tons of ash spewed into the atmosphere from a 2010 Icelandic volcano it caused havoc for vacationers across Europe. But did it also dramatically change clouds? Researchers at Pacific Northwest National ...

New technique allows study of clouds in 3-D

4 hours ago

With two off-the-shelf digital cameras situated about 1 kilometer apart facing Miami's Biscayne Bay, Lawrence Berkeley National Laboratory scientists David Romps and Rusen Oktem are collecting three-dimensional ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.