Instruments that record seismic wave amplitude at a given point on the Earth’s surface.
Instrument that measures horizontal ground movements.
Graphic representation produced by a seismograph; the stronger the tremors, the greater the oscillations on the paper.
horizontal ground movement
Secured to the ground, it rotates under the pen, recording ground movements on paper.
Independent of ground movement, it remains stationary during an earthquake, thus serving as a reference for measuring the amplitude of tremors.
Writing instrument that converts ground movement into a line.