NET NEWS: Charting the Shakes From Quakes

Science  24 Dec 1999:
Vol. 286, Issue 5449, pp. 2423
DOI: 10.1126/science.286.5449.2423b

For everyone who has wondered where to live to avoid getting rattled by an earthquake, a new map provides some hints. Last week, earth scientists released on the Internet the first global map that shows the odds of severe ground shaking during earthquakes for the next 50 years. The map will help engineers design safer buildings in regions that face high hazards.

Many geological atlases chart the world's major faults and pinpoint where big quakes have struck. However, such maps don't reveal the strength of ground shaking, which varies greatly depending on the nature of the earthquake and the landscape around it. For instance, a giant quake off the coast or far underground may produce only mild shaking in the closest city, while a small quake can wreak havoc if its fault breaks the surface where people live.

The new map, unveiled at an American Geophysical Union meeting in San Francisco, takes all such factors into account to quantify the chances that a particular region will feel shaking motions ranging from negligible to severe. More than 500 researchers worked on the world map (and regional maps, also available on the site) for 6 years, using satellite measurements, field surveys, historical records, and other data, says the project's director, Domenico Giardini of the Swiss Seismological Service in Zürich. Seismologists in many countries had few such maps or had waited until major quakes struck to predict future shaking, Giardini notes. About 15% of the world's land areas face a high to very high risk of severe shaking in the next few decades, say the map's authors. The most dangerous zones include Southern California, Iceland, Taiwan, Turkey, and around the India-China border.

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