Editing Seismometer (section)

=== Other forms ===
[[File:Kinemetrics seismograph.jpg|thumb|A Kinemetrics seismograph, formerly used by the [[United States Department of the Interior]].]]

[[File:Seismograph measuring visitors stomping their feet (often deliberately) at the Thomas A. Jaggar Museum, Hawaiian Volcano Observatory.webm|thumb|Seismometer in operation recording a seismogram.]]

Accelerographs and [[geophone]]s are often heavy cylindrical magnets with a spring-mounted coil inside.  As the case moves, the coil tends to stay stationary, so the magnetic field cuts the wires, inducing current in the output wires.  They receive frequencies from several hundred hertz down to 1&nbsp;Hz.  Some have electronic damping, a low-budget way to get some of the performance of the closed-loop wide-band geologic seismographs.

Strain-beam accelerometers constructed as integrated circuits are too insensitive for geologic seismographs (2002), but are widely used in geophones.

Some other sensitive designs measure the current generated by the flow of a non-corrosive ionic fluid through an [[electret]] sponge or a conductive fluid through a [[magnetic field]].