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Site content related to keyword: "earthquakes"

OFR3 Preliminary Report on the Earthquake of February 28, 1973

OFR3 Preliminary Report on the Earthquake of February 28, 1973

This report has been prepared to fill an immediate need for information on the earthquake that affected northern Delaware on February 28, 1973. Public interest in seismic events has grown in the past two years because of a series of small, local events (Jordan et al., 1972) and has been heightened considerably by the event described in this report. Various stresses on and within the earth lead to periodic adjustments or changes by the rocks making up the earth's crust. Many changes are too slow or small to be measured within a human lifetime, but earthquakes can be a very perceptible phenomenon, expressing more rapid adjustment. Indeed, earthquakes in many areas of the world are a serious geologic hazard and a threat to life and property. Thus, it must be recognized that the earth is a dynamic body and its processes are not bound to the convenience of man.

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OFR2 Preliminary Report on Seismic Events in Northern Delaware

OFR2 Preliminary Report on Seismic Events in Northern Delaware

Earthquakes are an unfamiliar phenomenon in Delaware. Because of the great public and scientific interest in the seismic events that have recently affected northern Delaware, this Open File Report has been prepared to present currently available information concerning the earthquakes and the investigation pursued by the Delaware Geological Survey. This is not a final scientific explanation of the events. To many persons it is shocking to realize that the earth that they regard as stable is, in fact, an active body. The present earth is a product of 4.5 billion years of history, during which time most geologic forces have acted so slowly as to be almost imperceptible. Therefore, sudden movements are disturbing. Earthquakes are the vibrations caused by relatively sudden slippage of deeply buried rocks. Earthquakes occur in a vast range of sizes; many are too small to be felt and others cause great damage. The events in Delaware that are described on these pages were relatively small and, although they warrant further study, which may lead to some precautionary measures, they do not represent cause for alarm.

RI39 Earthquakes in Delaware and Nearby Areas, June 1973 - June 1984

RI39 Earthquakes in Delaware and Nearby Areas, June 1973 - June 1984

Earthquakes in Delaware and surrounding areas have been well documented historically since about the early 1700’s and since 1972 by instrumental records. Most of the Delaware events have occurred in the Wilmington area immediately adjacent to or within rocks of the Wilmington Complex. Since the compilation of earthquakes by Jordan and others (1974) which lists events through May 1974, six felt earthquakes have occurred in northern Delaware and about 20 additional events in Delaware have been recorded on seismographs of the Delaware Geological Survey. Four of the felt events took place from November 1983 through February 1984 and ranged from a magnitude 1.5 to 2.9. The highest intensity for this series of earthquakes was a possible V (Modified Mercalli). Epicenters were generally in the north Wilmington area as determined both instrumentally and by felt reports.

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SP23 Earthquake Basics

SP23 Earthquake Basics

This report provides a brief overview of the causes of earthquakes, how earthquakes are measured, and a glossary of earthquake terminology.

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Earthquake rattles New Jersey and Delaware

Earthquake reported July 1 (credit NBC News 10)

A minor earthquake occurred near Pennsville, N.J., at 9:44 a.m., Wednesday, July 1, according to the Delaware Geological Survey (DGS) at the University of Delaware. The earthquake, which had a magnitude of 2.8, was recorded at the three northern stations of the DGS seismic network.

Earth's shift rattles state, some nerves - Centered in N.J., quake sounded like a loud noise

Delaware Geological Survey geologist, Stefanie Baxter shows the seismic recordings from detectors Wednesday.

When the earthquake hit a little before 10 a.m., everyone who heard the crack and felt the ground rumble thought something had exploded or crashed. Chimneys fell over, windows shattered, people panicked -- on Oct. 9, 1871. The magnitude 4.1 earthquake that shook Wilmington that morning -- the most intense temblor ever recorded in Delaware -- easily outshook the magnitude 2.8 quake that hit the state Wednesday morning.

Overview of Earthquakes in Delaware

DGS Seismic Recorder

Earthquakes occur in northern Delaware and adjacent areas of Pennsylvania, Maryland, and New Jersey. Over 550 earthquakes have been documented within 150 miles of Delaware since 1677, and 69 earthquakes have been documented or suspected in Delaware since 1871.

The Geology of Delaware

The Geology of Delaware is an online resource for information abo