In Tennessee, United States
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Welcome to Reelfoot Lake! The lake was formed by a series of earthquakes from the New Madrid Fault. Girl Scouts from troops 1629 and 1632 researched the lake's formation during a three-week study of letterboxing and geocaching.
Reelfoot Lake is located in the northwest corner of Tennessee. A series of earthquakes formed Reelfoot Lake during the bitter winter of 1811 and 1812.
Reelfoot Lake was once a swamp, regularly flooded by the Mississippi River. During the last 6,000 years the river has changed its course many times, leaving behind bodies of stranded water called oxbow lakes.
Reelfoot Lake probably was once a series of oxbow lakes. Then earthquakes 70 miles southwest of the lake, near the settlement of New Madrid, Mo., enlarged the land's low-lying basin. The quakes could be felt for one million square miles, from as far north as Canada to as far south as New Orleans.
Landslides swept down bluffs, large areas of land were uplifted, and still larger areas of land sank. One of these sunken areas filled with water, and Reelfoot Lake was born. People who lived near the Mississippi River said it appeared that the river ran backward for days as the water poured into the new lake.
The quakes also uplifted the area called the Tiptonville Dome. This runs below the south end of the lake, and it helped keep water from draining out of the area.
One major earthquake happened on Dec. 16, 1811. It measured 8.6 on the Richter scale. The next one was on Jan. 23, 1812. It measured 8.4. Finally, a quake Feb. 7, 1812, measured 8.7. Few lives were lost as the area was sparsely settled.
The lake covers 15,000 acres in water. Reelfoot Lake is now well known for hunting and fishing.
The New Madrid Fault, from which the earthquakes originated, is still active today. In recent decades, minor earthquakes have occurred. Scientists think that in the next 50 years there is likely to be a quake with a magnitude greater than 7.0 on the Richter scale. This could destroy the levee and spillway system that isolated the lake from the Mississippi River. If the area lifted up, the lake would drain. A major earthquake could also potentially destroy the city of Memphis, Tenn., which was not built when the last major quakes occurred.
To get credit for finding this cache, e-mail the answers to the following questions to the cache owner.
What time of day did the "hard shock" occur?
How many recorded tremors were there?
At what interval do scientists predict powerful earthquakes will occur in this area?
(No hints available.)
Last Updated: on 12/1/2013 10:31:26 AM (UTC-08:00) Pacific Time (US & Canada) (6:31 PM GMT)
Coordinates are in the WGS84 datum