catalogo de terremotos para america del sur catalog of earthquakes ...

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magnitudes are listed as mb magnitude3 but their methods for computations of
magnitudes differ. In Table 5 under the source codes GS and MOS, references
are listed which describe how these magnitudes were computed. Some magnitudes
were derived by local institutions during this project and a description of
these computations follows here.
Argentina: Both m 1 and M. magnitudes are included. A description of
these magnitudes is given in Cartaena and Castano (1973).
Bolivia: .lagnitudes (mb) reported with the source code SCB were derived
from M 1 magnitudes as follows:
mb = 0.65 + 0.89 ML (.)
The ML magnitudes in this relationship were determined using the following
relationship:
ML = log(A/T) + 1.8 log (A) + 3.5 (2)
where A is the maximum amplitude in microns of the S-phase from the short­
period seismogram and T the predominant period for the same train of waves; A
represents the epicentral di:utance in degrees and 3.5 is the scale correction
in order to match the Richter definition. Other magnitudes are also listed
with the scale codes &, F, and M. Magnitudes with the code G are ML
magnitudes whiuh w,'re calculated using equation 2 above. Magnitudes with the
code P are mb magnitudes converted from M s magnitudes reported by Pasadena
using the following equation:
mb = 2.37 + 0.56 M s
Magnitudes with the scale code M are ML magnitudes converted from maximum
intensity (Io) on the MM scale using the following equation:
(3)
ML = 1.08 + 0.6228 I o (4)