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

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mb = 1.63 + 0.60 log(A t), or
mb = 2.29 + 0.55 log(A T)
where A t = total area affected in km 2 , corresponding to the isoseismal curves
II M, and
AIV = the area of the isoseismal curve IV MM in km 2
These equations give good result for tectonic earthquakes which have occurred
in the continental intrapiate region of South America.
For the earthquakes with instrumental data with A between 200 and 1500
km, the following relationship is used (Assumpcao, 1983):
m R = log (27T A/T) + 2.3 logA - 2.28
mRmhere= magnitude with regional data, equivalent to m b
A = maximum amplitude of the real shaking of the ground in micrometers
(11m)
T = period in sec. corresponding to A
A = epicentral distance in km.
For the events with instrumental data with A less than 200 km, the
Richter method (1958) is used for the calculation of I 1 .
Determination of Intensity and Procedure Used.
For the evaluation of the intensity the Modified Mercalli Scale was used
(Wood and Newman, 1931). All of the macroseismic data, for each event, were
evaluated separately by four of the authors of the seismic catalog for Brazil.
When the separate evaluations were similar, the mean was adopted as the value
for the final intensity, for each place analyzed. When there was discrepancy
in Lhe values, a discussion was held in order to reach acceptable value.
The maximum epicentral intensity, in the case of earthquakes with an
epicenter in the ocean, but felt in the continent, the maximum epicentral
intensity was inferred using empirical relationships of variation of intensity
with distance, deduced for events in the region with known maps of isoseismal
curves.
UP DATE OF TiE CATALOGUE
As has been mentioned before, the earthquakes which have occurred since
1982 are published in la Revista Brasileira de Geofisica, thus providing material
for a permanent up date of the catalog, since the parameters are