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A present day's seismograph
records the data of
seismic oscillation
on magnetic tapes
or memory tips as electric signals.
We can therefore convert
this oscillation
into acoustic oscillation
to hear as "sound".
For example,
if we replay the data
of electric signals of
seismic oscillations
100 times as fast as
original speed, then 1 minute
in the real observation time
is shortened (compressed)
to be 0.6 second;
thus the frequency of
the seismic oscillation
is multiplied by
100 times, and we can hear
a seismic oscillation of 10Hz
as a sound of 1,000Hz.
Three different kinds
of seismic vibration are
presented below.
Converting these vibration
into acoustic oscillation,
we can hear these as
different "sounds".
Thereby we can distinguish
vibrations due to
pyroclastic flow
or volcanic tremor or
aftershock, and we
can estimate
what happens under (or on)
the ground.
Select a sound type
fit to your PC
from the menu on the
right-hand side of
the figures below,
and click!
You can listen to three
different types of seismic vibrations.
These vibrations are
replayed 81.9 times faster than
the original speed.
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