seismograph


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seismograph

an instrument that registers and records the features of earthquakes. A seismogram is the record from such an instrument

seismograph

(sÿz -mŏ-graf, -grahf) An instrument used in seismology to detect and record the passage of seismic waves, normally by making a continuous recording of the position of a suspended mass in relation to a frame fixed to the ground.

Seismograph

 

an instrument that records oscillations of the ground caused by seismic waves.

Figure 1. Diagram of a seismograph: (1) seismometer weight, (2) damper (device to attenuate the free oscillations of the weight), (3) device for converting the movement of the weight into an electrical signal, (4) filter-amplifier, (5)recorder

A seismograph (Figure 1) consists of a seismometer—an instrument that receives the seismic signal—and a recording device. The basic part of the seismometer is a weight connected with the case of the instrument by elastic couplings, for example, a pendulum. The case of the instrument is rigidly fixed to the object being studied. When the object oscillates, inertia causes the weight to move relative to the case. In most modern seismometers, this movement is converted into an electrical signal, which is recorded, usually in analogue form, by a mechanical, photographic, or magnetic recorder. Coded digital recording is sometimes used to increase the dynamic range and for convenience in subsequent computer processing.

There are also simpler seismographs, in which the movement of the seismometer weight is magnified mechanically or optically and is recorded by a mechanical or photographic recorder.

D. P. KIRNOS

seismograph

[′sīz·mə‚graf]
(engineering)
An instrument that records vibrations in the earth, especially earthquakes.
References in periodicals archive ?
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The end of the cable is equipped with a node (enhanced branching device) that features a broadband seismograph, acceleration seismograph, tsunami pressure gauge, conductivity temperature and depth-sensor and underwater microphone.
2 : to show a measurement of <A seismograph records the strength of earthquakes.>
With a magnitude of between 9.1 and 9.3, it is the second-largest earthquake ever recorded on a seismograph. It had the longest duration of faulting ever observed, between eight and 10 minutes, causing the entire planet to vibrate.
hears somebody ask, like a tremble on a seismograph, but you can't
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