Seismology
Seismology (from
the Greek seismos = earthquake) is the scientific study of earthquakes
and the propagation of elastic waves through the Earth. The field also
includes studies of earthquake effects, such as tsunamis as well as diverse
seismic sources such as volcanic, tectonic, oceanic, atmospheric, and artificial
processes (such as explosions). A related field that uses geology to infer
information regarding past earthquakes is paleoseismology. A recording
of earth motion as a function of time is called a seismogram.
This is a typical 24 hour plot of activity from the Guralp digital seismometer at Fernbank. To the left of the red marker is the most recent trace, to the right is 24 hours old. The time on the left axis is Universal Time (UTC) in a 24 hour clock format (e.g. 13:00 is 1 p.m.). Click on the image for a larger view. |
Fernbank Seismometers
A Sprengnether long period vertical seismometer sits on a concrete pier which extends three feet into the ground. Elastic earthquake waves from distant events cause the pier to move, which is detected by the seismometer.
A Guralp digital vertical seismometer detects earthquakes and stores the events on a computer. A styrofoam box insulates the sensor from temperature changes.
The electronic signal generated by the seismometer is amplified and recorded on a 12-inch drum seismograph. Precise time is marked every minute on a paper seismogram. Large earthquakes from around the world can be recorded. |
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National Earthquake Information Center |
