|Dr. Rick Aster stands in the crater created by a 2,000-pound ANFO explosion. Dave Thomas photo|
|A BBC film crew tags along with Rick Aster as he deploys a seismic station on the EMRTC test range. Dave Thomas photo
|Kaboom! This photo shows the shockwave, visible on the ground and above the blast along the skyline. EMRTC photo
The show’s producers interviewed Dr. Rick Aster, who is the principal investigator in charge of the Instrument Center and a geophysics professor in the Earth and Environmental Science Department at Tech.The BBC crew aimed to demonstrate how the seismic waves from earthquakes – or man-made explosions – travel through the Earth. An EMRTC crew set up a 2,000-pound ANFO explosion and filmed the blast. Aster and PASSCAL scientists Dave Thomas and Mouse Reusch deployed three seismic sensors to monitor the blast, along with seven other permanent stations from five to 44 kilometers away that are part of the Socorro Seismic Network. The documentary also will feature several high-speed, slow-motion films of the explosion.
After capturing seismic data from the blast, Aster displayed data plots that show the seismic waves measured near Ground Zero, and at the seismic stations placed one and two kilometers away. The plots show how the seismic waves travel much faster than the air-borne sound waves from the blast, and how the higher-frequency portions of the signals are attenuated as they propagate underground. On another plot, Aster showed the readings from all 10 seismic stations. He also described how fast and far seismic waves can travel, and what type of sources are required to penetrate thousands of kilometers to the Earth's core.
Aster explained and demonstrated how seismic waves can be used as a subsurface probing tool. He also talked about how Earth scientists combine data from many hundreds of stations to yield images of subsurface structures and gain new understandings of dynamic subsurface processes at work.
Aster, who recently completed a two-year stint as the President of the Seismological Society of America, is a renowned international expert on geophysics and seismology.
Another current show also focuses on seismology and other high-tech sensing technologies. The National Geographic Channel special X-Ray Earth reported on the EarthScope project, which is an ambitious continent-wide project to image the deep Earth. That show first aired May 15 and airs again tomorrow (May 24). For other re-broadcast times, check www.nationalgeographic.com.
Similar to the way doctors use X-rays to diagnose unseen medical problems, scientists are using an army of sensors located underground, in the sky, the ocean and our cities to monitor the Earth more than at any other time in our history. From the undisturbed far reaches of the planet to the busiest cities on the globe, X-Ray Earth uses technology and CGI to give us a new view of our world. EarthScope is one of the projects profiled on X-Ray Earth. The PASSCAL Instrument Center builds and maintains the 400 seismic stations that are deployed across the United States.
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