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.
The Delaware Geological Survey (DGS) currently monitors groundwater levels in a network of wells in Delaware. Long time-series of water levels in major aquifers serve as critical baseline data for resource management and analyses of aquifer response to pumping, climatic variability, drought hazards, seawater intrusion, and interaction with streams and their ecosystems.
Two state agencies, the Delaware Emergency Management Agency (DEMA) and the Delaware Department of Natural Resources and Environmental Control (DNREC), collaborated with the University of Delaware and the Delaware Geological Survey (DGS) and found an answer in the Delaware Environmental Observing System (DEOS). DEOS was created in 2003 as a real-time, regional monitoring system that provides data on weather conditions, water levels, snow depth, and various other environmental factors obtained from automated weather stations in and around the state.
The Delaware Geological Survey has a continuing program to map the geology of the entire state at the detailed scale of 1:24,000. The STATEMAP component of the National Cooperative Geologic Mapping Program has contributed significantly to our surficial geologic mapping program. This work has resulted in not only new geologic mapping, but also the digital compilation of previous mapping. Products of this program include file formats that can be downloaded and printed from the web as geologic map products and imported into GIS software as georeferenced layers.
William "Sandy" Schenck lead a field trip through the Delaware Piedmont for the A.I. duPont High School Earth Science Class. The trip made use of the Wilmington-Western Railroad and everyone rode the railroad's "Doodle Bug." Activities included up close examinations of rock and mineral features and even "Panning for Garnets" at Brandywine Springs Park.
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.
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.
The Delaware Geological Survey Cartographic Information Center has made the DGS a focal point for questions concerning the availability of all types of aerial photography, thematic maps, planimetric maps, topographic maps, historic maps, LANDSAT imagery, space imagery, side looking aerial radar imagery (SLAR), and geodetic control. Sources of maps, charts, aerial photography, boundary mark information, and vertical geodetic control can be obtained for your area of interest within the State through the Center's computer-searchable data bases.