1998 Pymatuning earthquake
The 1998 Pymatuning earthquake occurred in the U.S. state of Pennsylvania on September 25, 1998. With a magnitude of 5.2, it was the greatest recorded earthquake in Pennsylvania's history.
Location
The earthquake's epicenter was at latitude 41°29′24″ N and longitude 80°22′48″ W in the Southern Great Lakes Seismic Zone, about 25 kilometers (16 mi) southwest of Meadville; its depth was 5 kilometers (3 mi).[1]
Impact
The earthquake caused minor damage in towns near its epicenter and was felt in the states of Ohio, Pennsylvania, Indiana, Michigan, New York, Illinois and New Jersey, as well as Southern Ontario in Canada.[1]
Hydrologic occurrences
After the earthquake many wells in the epicentral region began to dry up, while new springs and old wells began to flow. A three-month date range revealed 120 dry household-supply wells. Declines of up to 100 feet (30 m) were observed on a ridge where at least 80 of these wells resided. The degree of the damage varied. Some of the wells lost all power or could barely hold their yields, and some of the water in wells turned black or began to smell of sulfur. An official explanation of these phenomena has not been arrived at, yet the most likely cause is the vertical hydraulic conductivity of shale rock under this area. In this scenario water could have leaked from the hilltops on the ridge.[2]
References
- ↑ 1.0 1.1 "Magnitude 5.2 Pennsylvania". United States Geological Survey. November 10, 2003. Archived from the original on 11 March 2009. Retrieved March 20, 2009.
- ↑ Fleeger, Gary M. et al. (1998). "Hydrologic Effects of the Pymatuning Earthquake of September 25, 1998, in Northwestern Pennsylvania" (PDF). Pennsylvania Geological Survey. Retrieved March 20, 2009.
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