Seismometer

Strong motion seismometer.

A seismometer or seismograph is an instrument that measures motions of the ground, including those generated by earthquakes, nuclear explosions and other sources.

Records of seismic waves called seismograms allow us to map the interior of the Earth, and to find and measure the size of those different sources.

The word derives from the Greek word, seismós, a shaking or quake, from the verb σείω, seíō, to shake; and μέτρον, métron, measure.

The technique of using a seismometer to build up a picture of the Earth's interior is called seismic tomography.

Seismometer Media

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  Basic horizontal-motion seismograph. The inertia of the round weight tends to hold the pen still while the base moves back and forth.

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  Replica of Zhang Heng's seismoscope Houfeng Didong Yi

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  Milne horizontal pendulum seismometer. One of the Important Cultural Properties of Japan. Exhibit in the National Museum of Nature and Science, Tokyo, Japan.

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  Simplified LaCoste suspension using a zero-length spring

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  CMG-40T triaxial broadband seismometer

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  Seismometer without housing; presented during a demonstration for children about earthquakes at Alfred Wegener Institute.

• Seismometer in operation recording a seismogram.

Other websites

• The history of early seismometers Archived 2003-04-15 at the Wayback Machine
• A Java code applet demonstrating the operation of a damped-mass seismometer
• Keeping track Archived 2009-02-01 at the Wayback Machine