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As the world turns, the Earth quakes

April 6, 2010
By Jayleen Heft

Have there have been more earthquakes lately, or have they just been reported more often in our modern 24/7 news cycle? Derek Schutt, seismologist and assistant professor of Geosciences, says actually, there's nothing new or unusual going on. The Earth has more or less the same amount of earthquakes every year.

A building destroyed by the 7.0 earthquake that struck Haiti on Jan. 12, 2010.

Stress causes faults to slip

Earthquakes usually occur at an existing fracture in the Earth's surface, called a fault. Plate tectonics, the process that causes continental drift, also produces stresses within the Earth that at some point may cause the fault to slip and produce an earthquake.

Unfortunately, we can’t predict when a fault will slip, or how big of an earthquake will occur on a given fault when it does slip.

Magnitude proportional to fault size

However, we do know that the maximum earthquake size is proportional to the size of the fault, and we know that these often occur in roughly periodic intervals, which allows us to estimate seismic hazard due to a fault.

The Earth has more or less the same amount of earthquakes every year, approximately:

  • 1 over magnitude 8
  • 17 magnitude 7.0 - 7.9
  • 134 magnitude 6 - 6.9

Derek Schutt, a seismologist and assistant professor of Geosciences at Colorado State.

Accidental seismologist

Schutt’s path to seismology was indirect. He was a math major, took an undergraduate geosciences overview course, and loved it. Schutt asked the instructor if there was a type of geoscience field that used a lot of physics and math, and he was directed to his future advisor. He had no real plan to get a Ph.D., but found the work so fun he decided to pursue his doctorate.

“I like physics and math, and I like being outside, and seismology and geophysics are great ways to combine my interests,” says Schutt.

So has the earthquake researcher ever experienced an earthquake? “I have experienced three earthquakes -- one in Illinois, one in Oregon, and one in California. Fortunately, I haven't been around for something large,” says Schutt.

In our neck of the woods

The largest earthquake in Colorado history occurred in 1882, and was roughly a magnitude 6.2. Since there were no seismometers around here then, we can only estimate that it occurred somewhere west of Fort Collins, perhaps around Estes Park, but no one has found the fault that caused it yet.

According to the Colorado Geological Survey, Colorado has about 90 faults that have moved within the last 1.2 million years. These potentially could be the source of an earthquake as large as magnitude 7.

A large crack in the earth along a fault in Iceland.

Few seismometers in Colorado

One difficulty is that we have had very few seismometers in the state. Because a fault that might produce a magnitude, say, 6 earthquake every 100 years would produce about a magnitude 5 earthquake every 10 years, a magnitude 4 earthquake every year, and so on, this means that if we can locate very small earthquakes we can find potentially active faults that may produce larger earthquakes.

“We are currently working with the Colorado Geological Survey to put in a seismometer in the Laramie River valley not too far from Cameron Pass,” says Schutt.

This, in addition to a few more seismometers that are being put in around the state, should do wonders for our ability to locate smaller earthquakes.

Fascinating classes, great careers

“Geology and seismology are loads of fun,” says Schutt. He has been to the Galapagos Islands, Oman, and Yellowstone doing research and studies. “And that's actually pretty tame for an Earth scientist,” says Schutt.

Oh, and the Geosciences Department is always looking for new majors -- who actually have great job prospects -- and the department has fascinating non-major introductory classes as well.