Thursday, September 6, 2012

New technology explores Earth’s Tectonic Hot Spots


New technology explores Earth’s Tectonic Hot Spots

By: Veronica Pineda

Acting as a historian, an observer, and futurist of our planet's movements, University of Utah Researcher Marie Green uses Magnetotelluric (MT) data to map out the thermal structure and fluidity underneath the surface of the US Pacific Northwest Region.

The Pacific Northwest Region is the most geologically diverse and active area of our continent to observe due to the dynamics of plate tectonics.

According to J. Figge’s publication Evolution of the Pacific Northwest, “The unique characteristic of this region is that it did not exist prior to Mid-Jurassic time. It consists of
 volcanic island belts and scraps of
 ocean floor rocks, which have been
 added to the edge of the continent
 over the past 200 million years, and
 overprinted by several episodes of 
volcanism and mountain building.”

This area is situated at the junction of three major tectonic plates (the Gonda, the Pacific, and the North American plate), otherwise known as the Mendocino Triple Junction, that slide, sub duct and collide in relation to one another.

“Prior to the breakup of Pangea and migration of subsequent land masses, Idaho defined the coastline of what became the North American Plate,” said Green.

As one continental plate clashes into the next, it sets off a chain reaction of geological transformation. The Cascadian Mountain Range, the Cascadian Volcanoes, the Columbia Basin, the geysers of Yellowstone, and the San Andreas Fault among many other geologic spectacles are evidence of these interactions

MT data allows scientists to see the anatomy of these features. It acts as a super detector of oil, mineral deposits, and the physical process of volcanic and earthquake eruptions.

“For such a complex region, definitive structural interpretation based purely on siesmological data may not be sufficient for reliable study of the deep earth interior,” said Green.

The obtained MT data can actually look at the changes of Earth’s substructure due to heat, molten fluidity, and other factors that fluctuate the resistivity.  

Green’s research with the Consortium for Electromagnetic Modeling and Inversion at the U consists of placing temporary stations that measure the electric and magnetic field variations from solar winds at any particular time and location.

These stations record how long that electric signal takes to reach the receptor, measuring the rate of decay on the field of that area’s subsurface.

The time at which it takes the signal to reach the other receptor determines how resistive the rocks are in the crust and upper mantle.

If the layer underneath shows low-resistivity, the rock underneath probably has enough fractures to have had fluid transport.

This fluid, or molten rock, would act as a lubricant for the tectonic plates to slide and push against each other causing earthquakes, volcanoes and other hiccups in Earth’s cycle.

Organizations such as; Earth Scope, US Array, National Science Foundation as well as Oregon State University are funding this worldwide project to observe and measure the motions of the Earth's surface, revealing the Earth’s geologic evolution. Also, over 300 stations have been deployed 70 km apart in a grid-like pattern to map the thermal structure of the crust and upper-mantel from the Pacific Coast to the Rocky Mountain range.

Recently Green’s Group has found evidence that the heat source of Yellowstone is not directly underneath. Instead, this channel of heat called a plume is located 40 to 80 km beneath the Snake River Plain and slowly moving further northwest.

"It’s migrating in the subsurface and is helping break up the crust all through here,” said Green.

The Snake River Plain extends 400 miles westward from Northwest Wyoming to the Idaho-Oregon border.  It is a broad, flat bowed depression that covers one quarter of the states. 


According to Green, the crust is moving over the upwelling mantle, causing expressions of basalt, a porous black igneous rock from volcanic activity that cools rapidly after lava drizzles on the surface.

Under the measured area, scientists can see the plume’s path as it breaches the Earth’s crust.

"It has these wormlike confutes coming from the surface of Yellowstone,” She said.

Scientists believe that these plumes are the driving mechanism for continental plate movement.

“From the data we're analyzing, it now seems like a regional phenomenon,” said Green.

The images from the MT data systems have mapped the Snake River Plane as the continuous source of magma from the mantle to Yellowstone—one that continues to be moving into other fault lines, changing the structure of our earth.

MT data research has only been around since the 1950s, and as it and alternative geological technology develops, scientists can catch another glimpse into the events that that make up the present world we live in.


This poster explains in depth the Green's MT research.

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