Procedure for calculating local magnitude,
from Earthquakes by Bruce A. Bolt (W.H. Freeman
and Company, 1988).
- Measure the distance to the focus using the time interval
between the S and the P waves (here S-P = 24 seconds).
- Measure the height of the maximum wave motion on the seismogram
- Place a straight edge between the appropriate points on the
distance (left) and amplitude (right scales to obtain magnitude
ML = 5.0.
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