Geophysical Instruments Information

MagnetometerGeophysical instruments are used for geological study, including rock and soil mechanics, and surveying the earth. Geological study can be subdivided into categories such as:

  • geophysics
  • geochemistry
  • mineralogy
  • hydrology
  • geomorphology

One area of geological study is seismology, the study of earthquakes (a sudden, sometimes violent movement of the earth’s surface from released energy in the earth’s crust) and related phenomena. Geophysical instruments for seismology are helping scientists learn more about the structure and properties of the earth’s crust and the causes and predictors of earthquakes. The use of geophysical instruments for earthquake detection is especially important.


Seismographs and magnetometers are the two main types of geophysical instruments used for surveying the earth’s crust and detecting earthquakes. A seismograph is a geophysical instrument that detects and records the intensity, direction, and duration of the earth's movements. A seismograph combines a seismometer (to detect movement and earthquakes) with a recording device to permanently record the occurrence and intensity of the earthquake. This allows seismologists to calculate how much energy was released during the earthquake and to identify the source of the earthquake.

A magnetometer is a type of geophysical instrument used to measure the strength and direction of magnetic fields. There are two basic types of magnetometers: scalar magnetometers (which measure the total strength of the magnetic field) and vector magnetometers (which measure the components of the magnetic field in a particular direction). Because magnetometers can measure the magnetic pull of iron, these geophysical instruments can also be used in a geophysical survey to locate iron deposits, ship wrecks, archeological sites, or buried objects.


Geophysical instruments must be properly calibrated in order to provide accurate readings. For example, the Richter scale is used in seismology. The Richter scale is a logarithmic scale that shows the total amount of energy released by an earthquake. The Richter scale is the most well-known scale to describe the intensity of an earthquake, but it is not the most accurate scale available to scientists.

Related Information

CR4 Community—Earthquake Pre Information Experienced

CR4 Community—Geologists Study China Earthquake for Glimpse Into Future

IEEE Spectrum—Earthquake Alarm

IEEE Spectrum—Satellites Watch for Warnings of Volcano Eruptions


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