Applied Science program plumbs depths of earthquakes and tsunamis

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Julie Colley

26 September 2007—Area science teachers and students grades 9–12 took a journey the center of the Earth with a noted professor of Earth and planetary sciences during Wednesday’s Applied Science program in San Antonio.

Michael E. Wysession, an associate professor at Washington University in St. Louis, Missouri, presented “A Geophysical Journey to the Center of the Earth” and answered students’ questions. The session was followed by a tour of some geophysical exhibits in the SEG exhibition hall.

Wysession is perhaps best known for his work in modeling the Earth’s mantle. In February 2007, he and Jesse Lawrence completed a model which points to an area of water saturation beneath the Earth’s crust, an area thought to be impossible for water to exist.

In the Applied Science program, he explained how plate tectonics are the foundation of geology, and that no other planet contains them. The Earth has seven major and many minor plates, with the North American plate containing parts of Japan and Siberia. Earthquakes occur where the plates meet at fault lines with the plates constantly moving; thus, earthquakes can occur anywhere. The best-known fault in the United States is the San Andreas Fault. The Pacific Plate, on which Los Angeles sits, has been measured to be moving northwestward at about the speed of human hair growth, relative to the North American Plate on which San Francisco sits.

Wysession emphasized the need for more research regarding the Earth to assist in predicting and, possibly one day, preventing devastating natural disasters. He discussed the Sumatra-Andaman earthquake in the Indian Ocean in December 2004. The resulting tsunami, according to the United Nations, claimed a total of 229 866 lives, including 186 983 dead and 42 883 missing. An estimated 994 mi of faultline slipped about 50 ft along the subduction zone where the India Plate, on which Sumatra lies, slides under the Burma Plate. The India Plate's collision with the Eurasian Plate created the Tibetan Plateau and the Himalaya Mountains between India and Nepal. This zone causes some of the world’s most devastating earthquakes.

 

In fact, earthquakes created the Himalayan Mountains along with every other mountain range on the planet, Wysession said. Here are some of the facts he shared with the audience:

 Tsunamis begin as a rise in the sea level rather than a giant wave and that they travel at the speed of a jet plane.

 Washington (USA) has a fault line the same size as the Sumatran with 9.0-scale earthquakes occurring every 400 years. The last major earthquake along this fault line occurred in the 1700s.

 Native American folklore in this region blames earthquakes and tsunamis on battling gods.

Research is constantly evolving, and while the science of today is impressive regarding prediction of natural disasters such as earthquakes and tsunamis, it will pale in comparison to research conducted as few as ten years from now, Wysession said.

His 3D model of the Earth’s mantle, which he developed earlier this year with former graduate student Jesse Lawrence (now at the University of California, San Diego), shows an area of seismic wave damping indicating a water reservoir the size of the Arctic Ocean, which he calls the Beijing Anomaly. If the model holds up to examination, it would show that variations in the Earth might not only result from temperature variation but also from the presence of water.

Wysession has written for G-Cubed, AGU Monograph, Earth Planetary Science Letters, Bulletin of the Seismological Society of America, Nature, Geophysical Research Letters, Journal of Geophysical Research, Journal of Geoscience Education, and other journals, and he has authored several books.

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