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Wednesday, April 11, 2012

Today's Indian Ocean Quake

This map was copied from the web site of the Earthquake Hazards Program at 7:50 a.m. Eastern Daylight-Savings Time today. It shows the 100 most recent earthquakes at that time (some dots cover other dots). EarthView students will recognize that most but not all earthquakes occur along the Pacific Ring of Fire or other plate boundaries. Whenever I see news of an earthquake, I check the program web site for details. It is a service of the United States Geological Survey, an agency of the Department of Interior that employs geographers, geologists, and biologists to create maps and analyze the geographic distribution of minerals, water, biological resources, and many kinds of natural hazards. Because an earthquake anywhere in the world can be detected everywhere in the world, the USGS is able to provide instantaneous reports on earthquakes, even if they are far from the United States.

This morning's earthquake was in the Indian Ocean, very near the quake that caused the devastating tsunami of December 26, 2004. For that reason, the USGS information about this morning's quake links directly to the tsunami program of the National Oceanic and Atmospheric Administration, which is part of the Department of Commerce. The preliminary magnitude estimate is 8.2. Buoy observations show wave heights ranging from 0.1 to 1.0 feet, and a detailed report estimates the time that waves should arrive in various locations throughout Indonesia and other countries surrounding the Indian Ocean. All locations are indicated by latitude and longitude, and all estimated or observed times are in Greenwich Mean Time (Zulu), which is four hours later that Eastern Daylight Savings Time.

The tsunami center provides data that individual countries and localities use in deciding whether to issue evacuation orders or warnings.

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