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1998 Pymatuning earthquake

From Wikipedia, the free encyclopedia

1998 Pymatuning earthquake
1998 Pymatuning earthquake is located in Pennsylvania
1998 Pymatuning earthquake
UTC time1998-09-25 19:52:52
ISC event1206808
Local dateSeptember 25, 1998 (1998-09-25)
Local time03:52 p.m. EDT
Depth5 km (3.1 mi)
Epicenter41°29′42″N 80°23′17″W / 41.495°N 80.388°W / 41.495; -80.388
FaultSouthern Great Lakes Seismic Zone
TypeOblique-slip reverse[2]
Areas affectedPennsylvania, Ohio
Max. intensityVI (Strong)[3]

The 1998 Pymatuning earthquake occurred in the U.S. state of Pennsylvania on September 25 at 19:52 UTC. With a magnitude of 5.2 mbLg,[1][4] it was the largest recorded earthquake in Pennsylvania's history.


The earthquake's epicenter was in the Southern Great Lakes Seismic Zone, about 25 kilometers (16 mi) southwest of Meadville; its depth was 5 kilometers (3 mi). 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.[5]

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 on the ridge of Jamestown and Greenville.[6] 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.

The most likely cause of the wells drying was because of the increase in hydraulic conductivity or "hydraulic islands" of shale rock under this area caused by the earthquake.[6] The quake affected the existing faults and created new faults in the shale.[6] This created more permeability for the water to leak down from the hilltops on the ridge down to the valleys following the contours of the Meadville shale down to the 14-18 square km area of the valley.[6]


  1. ^ a b Maceira, M.; Ammon, C.J.; Herrman, R.B. (2000). "Faulting Parameters of the September 25, 1998 Pymatuning, Pennsylvania Earthquake". Seismological Research Letters. 71 (6): 742–752. doi:10.1785/gssrl.71.6.742.
  2. ^ "USGS focal mechanism". Retrieved 2020-08-11.
  3. ^ ""USGS ShakeMap data". Retrieved 2020-08-11.
  4. ^ "USGS differential magnitude list". Retrieved 2020-08-11.
  5. ^ "Magnitude 5.2 Pennsylvania". United States Geological Survey. November 10, 2003. Archived from the original on 11 March 2009. Retrieved March 20, 2009.
  6. ^ a b c d Gorokhovich, Y; Fleeger, G (2007). "Pymatuning earthquake in Pennsylvania and Late Minoan Crisis on Crete". Water Science and Technology: Water Supply (Vol 1 No 7): 245–251. doi:10.2166/ws.2007.028.

This page was last edited on 2 September 2020, at 08:29
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