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Predicting Earthquakes

Trinity University Geoscientist Focuses on How, Not If, Temblors Will Happen

By Susie P. Gonzalez 

When Trinity geoscientist Glenn Kroeger talks about earthquakes and their resulting tsunamis, he sounds like a prophet of doom.

"Monster” earthquakes – those with magnitudes 9.0 or greater – could happen in regions such as the Pacific Northwest in the United States or the west coast of South America as soon as tomorrow, he says. “It’s not a matter of ‘if’, but ‘when.’ It’s going to happen. There is no avoiding it,” Professor Kroeger says of a powerful quake with the potential to cause widespread damage.

An earthquake with a magnitude of at least 9.0 last occurred near what is now Seattle and Portland, Ore., in January 1700, he says, adding that no local human records existed, but tree rings and other environmental data proved the occurrence of the catastrophic event. But Japanese records exist, and on Jan. 26 of that year, Japan – across the Pacific Ocean – was hit by a tsunami triggered by the massive quake, Professor Kroeger adds.

Watch Professor Kroeger's TV interview about Japan's 9.0 magnitude earthquake.

The earthquake that rocked Chile on Feb. 27 – weighing in with a magnitude of 8.8 – was not the biggest quake to strike that country. Professor Kroeger says the largest earthquake in the last century, measuring 9.5, occurred in Chile in 1960.

While scientists are unable to predict when a large-scale quake will happen, they are able to forecast where they are likely to occur, he says. “Earthquakes don’t happen at regular intervals. Earthquakes like that (8.8 magnitude or higher) only happen a few times in a millennium.” The Feb. 27 Chilean quake was the fifth largest earthquake logged since scientific recordings began just over a century ago.

The recent Chilean earthquake provided what Professor Kroeger calls “a teachable moment,” adding, “The time students want to learn about a significant earthquake is the day after it happens.”

With that in mind, when Professor Kroeger learned of the quake in Chile early on the morning of Saturday, Feb. 27, he immediately logged into IRIS, the Incorporated Research Institutions for Seismology, a National Science Foundation-funded consortium of universities that manage the worldwide network of seismometers and the storage and distribution of earthquake seismic data. Professor Kroeger chairs the education and outreach component of IRIS. Together with other scientists and IRIS staff, they developed a Power Point presentation and related files that could be downloaded by earth science teachers in middle schools and high schools or geosciences professors at institutions of higher learning throughout the United States. The first materials were distributed to educators before the resulting tsunami had reached Hawaii that Saturday afternoon. By Monday, educators had visited the site about 12,000 times to retrieve those educational materials, he says.

Questions have arisen about why the Jan. 12 quake in Haiti (7.0 magnitude) devastated that country, killing upwards of 200,000, while the Feb. 27 Chilean quake (8.8 magnitude) caused about 500 deaths. Although the Chilean quake released 500 times more energy, the key is where the earth broke, Professor Kroeger explains.

The fault line in Haiti ran directly through Port-au-Prince where the population density was high and construction standards were lax, Professor Kroeger says. The fault broke just 15 miles from the city about eight miles beneath the surface. By contrast, Chile has tougher building codes, he notes, adding that the rupture started offshore, 20 miles below the Earth’s surface and 200 miles from the capital of Santiago. If the Chilean quake had occurred farther north in metropolitan areas, the damage and possible casualties would have been more extensive, he says.

Courses Taught

  • Environmental Geology
  • Exploring Earth
  • Oceanography
  • GIS and Remote Sensing
  • Tectonics
  • Geophysics

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