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

Shallow: 0-70 kms.
S11
Intermediate: 70-300 kms.
Deep: Greater than 300 kms.
The second plot groupEd the events into two magnitude ranges: one with
6.5 > M s < 8.0, and the second with magnitudes > 8.0. Events with magnitudes
> 8.0 are labeled by year of occurrence. In order to divide the events into
rajiges based on M. magnitudes, it was necessary to compute an M. magnitude for
events which iad only an mb magnitude reported or only a maximum intensity. A
least squares regression was done, regressing Ms on mb using the catalog data
for events of a depth less than or equal to 55 kms. The value of 55 kms was
selected as the cutoff for shallow events after a qualitative examination of
the distribution of depths in the catalog. This regression produced the
following formula:
M s = -6.411 + 2.18 mb (1)
This formuia was used to compute an Ms value if there was no M. value but an
mb value was available. A second regression was done regressing Ms on Io,
also for events with a depth less than or equal to 55 kms. This regression
produced the following equation:
M s = 1.26 + 0.63 I o
This is very similar to the equation derived by Gutenberg and Richter (1956)
which is:
M = 1 + 2/3 I o
Equation 2 was used to compute Ms from Io if no magnitude values were
available. In Chile, estimated values of Ms (listed under other magnitudes)
(3)
(2)