Extract from the CD-ROM – Convection within the Earth developed in partnership with the ENS.


Principle of a mechanical seismometer

Mechanical seismometers are devices consisting of a pendulum. At the passage of an earthquake, according to the principle of inertia, the pendulum, that is a heavy mass, moves with a certain delay. Connected to a pen, the pendulum allows the recording of the seismic waves on a rotating drum (in that case vertical movements).