SOUNDS OF SEISMOLOGY:
Earthquakes in Sumatra: demonstration of magnitude with sound
The largest earthquake that has and probably will occur in your lifetimes has already happened,
in 2004 in Sumatra. This region is very active, seismically... so we compare three earthquakes
from approximately the same fault, with very different magnitudes, about M5, M7 and M9,
to demonstrate the meaning of magnitude. Since we cannot use volume to demonstrate these
differences in a true way, we use the duration of the ringing of the Earth after each earthquake.
The larger the magnitude, the farther the waves travel and the longer the earth is ringing.

Northern Sumatra, Mw 7.2, 2002/11/2 1:26 GMT
with Mw 5 aftershock
12 hrs at 20 sps
40 k