Earthscope (Image 4)
June 11, 2010
Drilling 35 feet to install a deep-drilled braced GPS monument (DDBM) near Parkfield, Calif. When practical, DDBM are the preferred installation type for EarthScope because their high stability allows for measurements of precise ground movements (millimeter per year precision) in both bedrock and softer sediments. [One of 14 related images. See Next Image.] More about this Image In a modern-day journey to the center of the Earth, geologists are exploring the structure and evolution of the North American continent at scales from hundreds of kilometers to less than a millimeter--from the structure of a continent, to individual faults, earthquakes and volcanoes. The project is called EarthScope. With approximately $200 million in funding from the National Science Foundation (NSF), EarthScope began development in 2004, and will continue over a five year period. It is expected to operate for an additional 15 years. EarthScope is using multiple technologies to explore the structure and tectonics of North America. For example, a four-kilometer deep observatory was drilled directly into the San Andreas fault to measure the physical conditions under which earthquakes occur there. One of 875 permanent Global Positioning System (GPS) stations has been installed, which can measure relative distance changes of less than 0.5 millimeters. EarthScope is one of an eventual network of 400 seismographic stations that will spread across the United States, making observations at more than 2,000 geographic locations to map the structure and composition of North America. EarthScope also provides unique educational opportunities as a national experiment, with its sensors located at more than 3,000 sites across the United States for measuring and observing plate tectonics in real time. For more information, visit the EarthScope Web site.
Topics: Seismology, Geography of California, Geology, Parkfield, California, Earthscope, Surveying, Monterey County, California, Global Positioning System, Earthquake, Geophysics, Plate tectonics, Navigation