Geophone
Device that converts ground movement (velocity) into voltage, which may be recorded at a recording station. The deviation of this measured voltage from the base line is called the seismic response and is analyzed for structure of the earth.
A geophone is a device that converts ground movement (velocity) into voltage, which may be recorded at a recording station. The deviation of this measured voltage from the base line is called the seismic response and is analyzed for structure of the Earth.
Etymology
The term geophone derives from the Greek word "γῆ (ge)
" meaning "earth" and "phone" meaning "sound".
Construction
Geophones have historically been passive analog devices and typically comprise a spring-mounted wire coil moving within the field of a case-mounted permanent magnet to generate an electrical signal. Recent designs have been based on microelectromechanical systems (MEMS) technology which generates an electrical response to ground motion through an active feedback circuit to maintain the position of a small piece of silicon.
The response of a coil/magnet geophone is proportional to ground velocity, while MEMS devices usually respond proportional to
acceleration. MEMS have a much higher noise level (50 dB velocity higher) than geophones and can only be used in strong motion or active seismic applications.
Frequency response
The frequency response of a geophone is that of a harmonic oscillator, fully determined by corner frequency (typically around 10 Hz) and damping (typically 0.707). Since the corner frequency is proportional to the inverse square root of the moving mass, geophones with low corner frequencies (< 1 Hz) become impractical. It is possible to lower the corner frequency electronically, at the price of higher noise and cost.
“Geophone” enters the record as device that converts ground movement (velocity) into voltage, which may be recorded at a recording station. The deviation of this measured voltage from the base line is called the seismic response and is analyzed for structure of the earth. Crown Archives preserves that source wording while asking what Geophone, Device and converts can confirm, complicate or overturn.
Why this record matters
“Geophone” is worth following because a concise public description often conceals a longer documentary argument. Here, Geophone, Device and converts provides the most credible route into that argument.
The strongest evidence will usually combine a dated visual record with documents produced by the authority responsible for the place. The source revision retrieved here is dated Feb 23, 2026. The linked authority identifier is Q361564. The Library of Congress control number is sh85054178. 1 of 1 selected statements include explicit references; 1 carry qualifiers and 0 use preferred rank.
Modern boundaries and familiar names can conceal earlier jurisdictions or structures that do not align with the present site. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “Geophone” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.