Seismographs measure vibrations produced during earthquakes. All earthquakes, regardless of size, generate vibrations deep within the earth. These vibrations are caused by the breaking and fracturing of rock and organic materials along fault zones; seismographs detect and record the frequency, duration and magnitude of all vibration waves emitted from earthquakes.
Seismographs are relatively basic in design; they contain sensing elements, called seismometers, which are amplifiers that provide detailed information on the types of vibrations captured, and display units. They set to work by detecting ground motion, which is measured against a fixed object; large objects do not move during quakes, which enables seismographs to take accurate measurements. Seismographs intake and interpret the results of an earthquake according to the vibrations produced. This information is digested, recorded and reproduced in a visual record, called a seismogram. According to EarthquakesCanada, many modern seismographs contain display units that are equipped with digital technology, such as digitizers, along with computer-oriented data storage equipment like removable disks. Many seismologists still use seismographs to take and record hard copies of earthquake data, but digital seismographs are valuable for rapidly storing and disseminating information gathered on earthquakes to other locations. Seismographs are generally quite accurate in producing results; errors in data collection are most frequently attributed to human error.