South Pole Seismic Station Is Very Quiet And Very Sensitive

TECTONICS

The tectonic structure of Antarctica remains largely a secret buried below a continent of ice except in a few places with the Trans Antarctic mountains breakthrough the ice cap.

Arlington - Mar 26, 2003
Data collected by a new seismic observatory at the National Science Foundation's (NSF) Amundsen-Scott South Pole Station indicate that it is the quietest listening post on the planet for observing shudders produced by earthquakes around the world as they vibrate through the Earth.

The South Pole Remote Earth Science Observatory (SPRESO) is located eight kilometers (five miles) from the South Pole and the new seismometers have been installed roughly 300 meters (1000 feet) beneath the surface of the continental East Antarctic ice sheet in specially drilled boreholes.

The newest station in the Global Seismograph Network (GSN), operated by the Incorporated Research Institutions for Seismology (IRIS), a research consortium of 100 universities based in the Washington DC, is now recording some of the smallest vibrations on Earth, some as much as four times smaller than could previously be recorded in the frequencies that are crucial for monitoring earthquakes both in Antarctica and globally.

"The extraordinarily quiet conditions proved at the new SPRESO site open a new dimension for establishing arrays of seismic sensors for exploring Antarctica and the Earth," according to Rhett Butler, who is the GSN program manager and the principal investigator for the project.

The new station, known by its four-letter station code "QSPA," has been under construction for the past two Antarctic summers. The work included the drilling of three 300-meter (1000-foot), 30-centimeter (12-inch) diameter holes and the construction and burial of a 22 square-meter (240 square-foot) heated electronics vault.

Ice Coring and Drilling Services (ICDS) at the University of Wisconsin conducted the drilling for the project. Raytheon Polar Services Co., of Centennial, Colo., NSF's support contractor in Antarctica, designed and installed the electronics vault as well as the power and communications links. Honeywell Technology Solutions, Inc. personnel, under contract to the U.S. Geological Survey, performed the station fieldwork and installed the seismic instrumentation.

The South Pole is a unique location for a variety of scientific research, notably astrophysics and astronomy, in part because it is located at the Earth's axis, which allows for long-term observations of a single spot in the sky. But that unique attribute also makes the Pole an unrivalled seismic observatory.

Large earthquakes make the Earth ring in the same way a bell does after being struck.

Analysis of these vibrations reveals information about the Earth's composition, especially when recorded at the axis of the globe, where the vibrations are free of the effects produced by the spinning globe.

The South Pole also is an ideal seismic observatory because seismographs have been operating there since the International Geophysical Year in 1957. Long-term data from high-latitude seismograph stations such as South Pole have helped to prove that the Earth's solid inner core spins at a slightly faster rate than the rest of the planet.

Antarctica is also the continent with the smallest number of earthquakes. Since the new GSN station is so quiet, it will be possible to record much smaller Antarctic regional earthquakes than ever before, leading to new insights into the evolution of the Antarctic Plate.

Seismic data from a previous seismic station at the Pole already was in high demand by researchers, though the station that was in service prior to QSPA at SPRESO was located very close to South Pole and was subject to noise from construction and other work at the station. SPRESO is located in a specially designated quiet zone at the Pole.

TECTONICS

Parts Of British Columbia In The Midst Of A 'Silent Earthquake'

Seattle - Mar 19, 2003
At this moment, parts of Washington and British Columbia are having an earthquake, but it is a slow-moving temblor that can't be felt and won't cause any injuries or damage.

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