Ground Motion - 3
A Combination of Waves
Real ground motion during an earthquake is made up of many
waves of different amplitudes
and frequencies.
(Explain).
The main shaking of the ground that is felt has frequencies
up to 20 Hertz.
This graph shows how the position of a patch of ground changed
with time during a real earthquake, the 1989 Kalamata earthquake
in Greece. The motion does not have the simple form of a single
wave with constant frequency and amplitude. Instead it looks
much more complicated. (Animate)
|