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	NASA Map Shows Earth's Tectonic Activity posted: 06:31 am ET 11 November 1999

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Most global geologic maps simply define plate boundaries on Earth's crust and show current seismic or volcanic activity. But a new map developed by NASA shows the broader architecture of Earth's crust and includes current and past activity of all geological structures.

Since the Digital Tectonic Activity Map (DTAM) expresses tectonic activity not just at the plate boundaries but at the intra-plate level (within plates), it provides researchers and educators with a more realistic picture of the Earths crustal dynamics which may lead to a better understanding of our volatile planet.

"The DTAM is different from the 'plate maps' common in geology textbooks because it shows not only well-recognized features such as the Pacific Plate, but it also shows broad zones of earthquake and volcanic activity that are not simply plate boundary features," said principal investigator, Paul Lowman, of NASAs Goddard Space Flight Center.

"For example, the map shows a belt of earthquakes off the coast of Norway, not usually considered a seismic zone or a plate boundary. These earthquakes may outline a previously unmapped fault zone."

The digital map also shows the motions of NASA space geodesy stations around the world. Using radio telescopes, NASA and cooperating scientists in other countries can measure intercontinental distances with an accuracy of half an inch (about one centimeter).

The data shows, for example, that the Hawaiian Islands are moving toward Japan at about three inches a year (about seven centimeters). The map also shows rates of sea-floor spreading and zones of volcanism where the oceanic crust is moving apart at the mid-ocean ridges.

The new digital tectonic map also provides a tool for researchers concerned with monitoring and predicting natural hazards such as earthquakes and volcanic eruptions worldwide. The digital map is published in the November issue of the Journal of Geoscience Education.

Based partly on spacecraft data, including orbital photographs, the map was generated primarily by computer software using publicly available data and commercial software. The data sources include Landsat satellites, hand-held astronaut photography and ocean topography data from other NASA spacecraft that use radar altimetry to gather sea surface measurements.