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Hydrologic effects of the Pymatuning earthquake of September 25, 1998, in northwestern Pennsylvania

January 1, 1999

Within hours after the Pymatuning earthquake of September 25, 1998, in northwestern Pennsylvania, local residents reported wells becoming dry, wells beginning to flow, and the formation of new springs. About 120 household-supply wells reportedly went dry within 3 months after the earthquake. About 80 of these wells were on a ridge between Jamestown and Greenville, where water-level declines of as much as 100 feet were documented. Accompanying the decline in water levels beneath the ridge was an increase in water levels in valley wells of as much as 62 feet. One possible explanation of the observed hydrologic effects is that the earthquake increased the vertical hydraulic conductivity of shales beneath the ridge, which allowed ground water to drain from the hilltops. Computer simulations of ground-water flow beneath the ridge between Jamestown and Greenville indicate that increasing the vertical hydraulic conductivity of shale confining beds about 10 to 60 times from their pre-quake values could cause the general pattern of decreased water levels on hilltops and increased levels in valleys.

Publication Year 1999
Title Hydrologic effects of the Pymatuning earthquake of September 25, 1998, in northwestern Pennsylvania
DOI 10.3133/wri994170
Authors Gary M. Fleeger, Daniel J. Goode, Theodore F. Buckwalter, Dennis W. Risser
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Water-Resources Investigations Report
Series Number 99-4170
Index ID wri994170
Record Source USGS Publications Warehouse
USGS Organization Pennsylvania Water Science Center
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