Well hydrograph before and after Pymatuning earthquake, Pennsylvania

Well hydrograph before and after Pymatuning earthquake, Pennsylvania

Detailed Description

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. 

A 3-foot rise in the ground-water level was recorded in USGS observation well MR-1364 in Greenville on September 25, 1998. The graph shows the water-level rise in this valley well. Water levels generally decreased in ridge-top wells.


Image Dimensions: 644 x 513

Date Taken:

Location Taken: Greenville, PA, US


USGS preparaed the graph. USGS monitored this well in cooperation with the Pennsylvania Department of Environmental Protection.