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

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Instrumental data from local agencies, observatories, stations, and
universities were also included. Compilation of the historical catalog
involved research through historic documents including periodicals,
newspapers, and local archives, and also inclusion of recent research on
historical events.
In undertaking a task of this size, it was necessary to emphasize certain
aspects of the compilation process, while leaving other aspects as future
refinements of the catalog. One of the primary tasks at this stage of the
catalog work was to eliminate duplicate listings for the same event. Since
data were collected from many overlapping sources, in the initial collection
of events the same event was often included multiple times. Inclusion of
events as unidentified multiple entries can bias any future hazard and risk
analysis. Two major problems arise in eliminating the duplicate events. The
first is to recognize that two or more entries are the same event when the
date, time, location, and magnitude reported by two different sources may
differ significantly. The second is to decide which data to keep and which to
delete. It is possible that in future versions of the hypocenter catalog
alternate entries for hypocenter parameters may be included as long as they
are identified as alternate entries and not additional events. However, at
this stage only one entry for each recognized event has been included.
Computer programs are of some use in recognizing potential duplicate
events, but human judgment is required to make a final decision on which
events are duplicates. This involved consideration of the accuracy of the
data for the given time period and for the given source, and evaluation of the
differences in time, location, depth, and magnitude. ISC bulletins associate
their hypocenter data with reports from other sources including the USGS.