földrengésérzékelket
Földrengésérzékelő is the Hungarian term for seismometers or earthquake detectors. These are sensitive instruments designed to record the ground motion caused by seismic waves generated by earthquakes or other vibrations. The fundamental principle behind most seismometers is inertia. When the ground shakes, the seismometer's casing moves with it, but a mass suspended within the instrument tends to remain at rest due to its inertia. This relative motion between the casing and the suspended mass is what is detected and recorded.
Early seismometers were mechanical, using levers and pens to draw a trace on a moving paper drum.