 
Top of Part 4
Next page
|
Seismograph
is an instrument which gauges
ground tremors.
Recent seismograph is
made up of a sensor module
called seismoscope and a
recording device
which consists of
an amplifier and a recorder,
shown as Figure 1.
Seismoscope converts
tremors into a series of
electric signals
by moving a coil attached
on the tip of
a pendulum
in a magnetic filed,
as shown Figure 2.
A set of three seismoscopes
is necessary to measure
up-down,
east-west and
north-south components
of the tremors
The recording device
receives, amplifies
and finally records
a series of
electric signals
from the seismoscope.
The recording methods
are varied. In old days,
tremors were directly
recorded by a pen
on a paper rolled
on a cylindrical drum.
Nowadays, we
mainly use computer
assisted digital recorders.
|
