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Site content related to keyword: "geohazard"

Milford (Q61A) Seismic Station

The seismic instruments located at the Milford, DE location were adopted by DGS from the Earthscope Transportable Array, which consists of a network of 400 high-quality, portable broadband seismometers that are being placed in temporary sites across the United States. DGS adopted two of these Earthscope stations, P60A in Greenville, DE and Q61A in Milford, DE. This program provided an outstanding opportunity for Delaware to enhance its seismic monitoring capabilities in the future, and upgrade current antiquated equipment.

Greenville (P60A) Seismic Station

The seismic instruments located at the Greenville, DE location were adopted by DGS from the Earthscope Transportable Array, which consists of a network of 400 high-quality, portable broadband seismometers that are being placed in temporary sites across the United States. DGS adopted two of these Earthscope stations, P60A in Greenville, DE and Q61A in Milford, DE. This program provided an outstanding opportunity for Delaware to enhance its seismic monitoring capabilities in the future, and upgrade current antiquated equipment.

Mapping Tsunami Inundation for the U.S. East Coast

National Tsunami Hazard Mitigation Program
Project Contact(s):

This project will assess tsunami hazard from the above mentioned and other relevant tsunami sources recently studied in the literature and model the corresponding tsunami inundation in affected US East coast communities. We will combine ocean scale simulations of transoceanic tsunami sources, such as Lisbon 1755 like or Puerto Rico Trench co-seismic events, and CVV collapse, with regional scale simulations of these events, along with the regional scale SMF events, in order to establish the relative degree of hazards for East Coast communities. Detailed inundation studies will be conducted for highest-risk East Coast communities, and results of these studies will be used to construct a first-generation of tsunami inundation maps for the chosen communities.

The Earthquake of August 23, 2011

Seismograph recording of the August 23, 2011 earthquake

Delaware and surrounding areas experienced an earthquake event on the afternoon of Tuesday, August 23, 2011. According to the US Geological Survey, a magnitude 5.8 earthquake struck at 1:51 p.m. in central Virginia, in an area referred to as “the Central Virginia Seismic Zone” because of its relatively active earthquake activity for the region. The epicenter was located five miles south-southwest of Mineral, Virginia, with the quake was focused at a depth of 6 km (3.7 miles) below the surface (http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/se082311a.html). The Virginia Geological Survey reports that this is the largest Virginia earthquake known in historic times. A few small aftershocks have occurred in the hours afterward.

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IS7 The Delaware Geological Survey

IS7 The Delaware Geological Survey

IS7 is a foldout brochure that briefly discusses the background and current activities of the DGS. Specifically, the following major programs are listed: Geology, Hydrology, Cartographic Information, Geologic Hazards, Seismograph Network, Outer Continental Shelf, Mineral Resources, Well Records and Sample Library, Publications, and Joint-funded Programs.

IS5 Earthquakes in Delaware

IS5 Earthquakes in Delaware

Delaware is not in a seismically active region but, even here, earthquakes occur because of sudden adjustments in the earth's crust. Even though such movements can be startling they yield important information about the behavior of the earth and the potential for future events. The Delaware Geological Survey continually monitors seismicity in the State because of both the scientific value of the information and to help address the concern of residents and other agencies over possible effects.

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A Coastal Flood Monitoring System for Delaware

Flooding at Kitts Hummock after the Mother's Day Storm 2008
Project Contact(s):

During the last two decades, storms such as Hurricanes Katrina and Ike along the Gulf of Mexico and Floyd and Hugo along the Atlantic Coast of the United States have resulted in significant loss of life, injuries, and property damages exceeding well over 100 billion dollars. Much of the damage associated with these and other tropical and extra-tropical weather systems is associated with severe coastal flooding. The purpose of this project is to develop a real-time coastal flood monitoring and warning system for the coastal communities in Kent County, Delaware. This system will serve as a prototype for similar early-warning systems, which may then be applied along the entire Delaware coast.

USGS Real-time Earthquakes Map

Maps and resources for real-time M1+ earthquakes.

Catalog of Delaware Earthquakes Spreadsheet

Catalog of Delaware Earthquakes Spreadsheet

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.

Seismic Network Map

The DGS maintains its own network of seismometers to detect local earthquake activity. Following an earthquake swarm in 1972, the DGS established its first seismometer station in Newark. The network now consists of five seismic stations spread across the state: three stations in the Newark-Wilmington area, one at the DEMA office in southern New Castle County, and one at the Sussex County Emergency Operations Center.

Earthquake Felt Report

Please answer every question to the best of your ability. Either fill in the blanks where called for, or check the response that best describes the event. If a question does not apply or if you don't know how to respond to a particular question, simply skip it and go on to the next. Feel free to add additional information in the Additional Comments box at the bottom of the form.

Sussex County Emergency Operation Center (SCOM) Seismic Station

Sussex County Emergency Operation Center (SCOM) Seismic Station. The seismometer, located on the property of the Sussex County Emergency Operation Center, is positioned on the Beaverdam Formation. The Beaverdam Formation is a very coarse sand with beds of fine to medium sand. It is interpreted to be a Pliocene fluvial to estuarine deposit.

Delaware Emergency Management Agency (DEMA) Seismic Station

Delaware Emergency Management Agency (DEMA) Seismic Station. The seismometer, located at the Delaware Emergency Management Agency, is located on the Columbia Formation. The Columbia Formation is a fine to coarse, feldspathic quartz sand with varying amounts of gravel. It is primarily a body of glacial outwash sediment deposited in a cold climate during the middle Pleistocene.

White Clay Creek State Park (NED) Seismic Station

White Clay Creek State Park (NED) Seismic Station. The seismometer, located in White Clay Creek State Park, is positioned on the Wissahickon Formation. The Wissahickon Formation is an extensive sequence of pelitic and psammitic gneisses interlayered with amphibolites. With few exceptions, most of the amphibolite layers are less than 30 feet thick. The rocks have been metamorphosed to upper amphibolite facies and isoclinally folded. The formation is located within the Wilmington North, Kennett Square, West Grove, Newark West, and Newark East U. S. Geological Survey 7.5-minute quadrangles.

Brandywine Creek State Park (BWD) Seismic Station

Brandywine Creek State Park (BWD) Seismic Station. The seismometer located at Brandywine Creek State Park is positioned on the Wissahickon Formation. The Wissahickon Formation is an extensive sequence of pelitic and psammitic gneisses interlayered with amphibolites. With few exceptions, most of the amphibolite layers are less than 30 feet thick. The rocks have been metamorphosed to upper amphibolite facies and isoclinally folded. The formation is located within the Wilmington North, Kennett Square, West Grove, Newark West, and Newark East quadrangles.

Bellevue State Park (BVD) Seismic Station

Bellevue State Park (BVD) seismic network station. The seismometer located at Bellevue State Park is placed on the Brandywine Blue Gneiss. The Brandywine Blue Gneiss is the new name given to the granulite-facies felsic gneisses in the Wilmington Complex. Informally called the “blue rocks,” this unit is a medium- to coarse-grained, lineated (pinstriped), two-pyroxene gneiss with variable quartz content and thin, discontinuous mafic layers, pods, and schlieren. The pinstriping and the massive nature of the rock suggest the rock is intrusive; however, deformation and recrystallization have obscured original igneous features.

Natural Hazards in Delaware

Hurricane Floyd - 1999

Natural hazards are those events in the physical environment that present risks to human life or property. The DGS identifies and investigates natural hazards to help understand the earth systems that present the hazards and determine strategies to prepare for or mitigate the risks. We are active in advising emergency management agencies on natural hazards, and are included in the Delaware Emergency Operations Plan as an agency having a vital role in dealing with floods, northeaster/extratropical storms, droughts, earthquakes, sinkholes, and dam failures.

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.

About the Delaware Geological Survey

The DGS Building, University of Delaware, Newark Campus

The Delaware Geological Survey (DGS) is a science-based, public-service-driven Delaware state agency at the University of Delaware (UD) that conducts geologic and hydrologic research, service, and exploration for the benefit of the citizens of the First State. The mission of the DGS is to provide objective earth science information, advice, and service to its stakeholders, the citizens, policy makers, industries, and educational institutions of Delaware.