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Browsing Open File Reports by Author "Baxter, S.J."
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Item Catalog Of Earthquakes In Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 2000) Baxter, S.J.The occurrences of earthquakes in northern Delaware and adjacent areas of Pennsylvania, Maryland, and New Jersey are well documented by both historical and instrumental records. Over 550 earthquakes have been documented within 150 miles of Delaware since 1677. One of the earliest known events occurred in 1737 and was felt in Philadelphia and surrounding areas. The largest known event in Delaware occurred in the Wilmington area in 1871 with an intensity of VII (Modified Mercalli Scale). The second largest event occurred in the Delaware area in 1973 (magnitude 3.8 and maximum Modified Mercalli Intensity of V-VI). The epicenter for this event was placed in or near the Delaware River. Sixty-nine earthquakes have been documented or suspected in Delaware since 1871.Item Results Of Trenching Investigations Along The New Castle Railroad Survey-1 Seismic Line, New Castle, Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 2002) McLaughlin, P.P.; Baxter, S.J.; Ramsey, K.W.; McKenna, T.E.; Strohmeier, S.A.Five trenches were excavated to a depth of 5 to 8 ft along the path of an abandoned railroad grade near the city of New Castle to investigate potential near-surface faults that may be related to earthquake activity in northern Delaware. Seismic reflection profiles along this line suggested the existence of significant faulting in the area, which lies along a postulated fault trend in eastern New Castle County. Subsequent drilling, however, failed to substantiate displacement interpreted for faults in the sedimentary section. Detailed examination of exposures in the trenches also failed to reveal the existence of near surface faults. Together these findings suggest that there has been minimal or no modern near-surface fault activity in this area of New Castle County.