To produce the highest quality seismic records, a seismometer must be placed in an area that has a low amount of ground vibration. " Seismic noise" can be produced by cars and trucks, air traffic, well pumps, wind, foot traffic, construction, and anything that produces loud noise. This man-made and atmospheric noise obscures the vibrations produced by small or distant earthquakes.
Seismometers must be place on bedrock for optimum operation. Seismic sensors directly in contact with bedrock pick up vibrations generated in the earth's crust during earthquakes. If the sensors are place on soil instead of on bedrock, extraneous noise transmitted by the soil w ill be superimposed on the earthquake vibrations, complicating the interpretation of the seismic records.
Therefore, the ideal place for a seismometer is in a quiet, remote area, far from busy urban activities. The seismometer site should have a thin soil cover to minimize soil noise. Thin soil also makes the installation and maintenance of the seismometer easier.
Soldiers Delight Natural Environmental Area, in western Baltimore County, is the site for the remote seismic station. This site offers a number of critical advantages for the placement of the remote seismometer. Because the land is administered by the Department of Natural Resources' Park Service, the site offers long-term security and infrastructure stability. An association with the Park Service also offers an excellent opportunity for educational outreach and public involvement in the seismic project.
The Soldiers Delight area is relatively isolated from heavy traffic, construction and other vibration-producing activities that would interfere with seismic measurements. Due to the unique geology of the Soldiers Delight area, soil cover is thin, an ideal condition for seismometer placement. This region also offers open spaces, clear of trees. Trees transmit wind energy to the ground and this creates seismic noise, which can degrade the quality of the seismic signal. Finally, the site is close enough to Maryland Geological Survey's facilities and has sufficient elevation to broadcast data back to the Survey.
No other sites that we explored in the metropolitan area offer all these ideal conditions. For more information about the geologic setting of Soldiers Delight Natural Environmental Area view our Soldiers Delight geologic tour page.