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

S03
These bulletins, for the time span for which they are available, were often
used as a reference in cases ofA do,:Lt to deterrinne if events were duplicates.
In general a p-ecedence ranking oK sources was used in determining which
entry for a given event should be retained. This varied among countries since
different sources were involved and in some cases events were given individual
attention to determine which was the best location for the event. A decision
was made that, in general, IS data should be given preference over GS data
for events from 1964 to the present in which both agencies reported the
event. This time period represents a large block of data In which ISC and GS
provided the primary sources of dana. It was decided that it would be best to
follow a consistent policy amongst all comntries in selecting the preferred
locations for these events. TSC was chosen as the preferred source because
they have available the samo wt-tion data as the USGS together with data from
aaditional stations which arrive after the USGS has computed a hypocenter
solution. For a time period covering 4he earlier pa;'t f the century,
Cutenberg and Richter data were usually given prefer,-'e over other data.
Beyond these generalized policies, determination of preferred locations was
usually left up to representatives from the individual countriew.
In the compilation of a large set of data, detection and correction of
data processing errors becomes a major concern. Some errors, were round in the
data obtained from the basic data compiled by USGS, NOAA and MSG; others were
Introduced during various phases of the comnilation of the catalog. it is
virtually impossible to eliminate all errors in Frocessing this amount of data
which has been colected from so many different sources. We have made
attempts to discover and correct as many errors as possible. In doing so, we
have concentrated on the hypocenter, magnitude, and intensity data, since
these parameters are essential in hazard and risk analysis.