Duplication:
A list of preferred networks for each region is used. Usually the network closest to
the event is expected to have the best local coverage and that is the location used.
For large teleseismic events, local magnitudes are usually lousy, and we use data
obtained first from NEIS, then GSR and down the line. Comparison of the final epicenters
after some time has elapsed has allowed a reasonable idea of which quick sources
are best for which regions.

Availability
Since no funds are used to maintain this database (an unpaid slave does the work)
the availability is subject to political considerations. NOAA does not wish to be seen
as in competition with the USGS in terms of earthquake catalogs and does not
consider this an essential part of their mission. The catalog is mostly used for internal
programs and data, but is available to engineering firms and others wishing to
do seismic studies. We spent a year last year trying to get the catalog on line
with limited success. The problem is that there are too many sub catalogs and
too many events for searches to be done quickly enough so as not to tie up the
system. There are no current plans to make this data available on-line.

Accuracy:
Accuracy is suspect for any immediate events. We have found, however, that
in recent years, the accuracy of locally determined epicenters is usually quite
good after the first manual review, and of teleseismic reporters within at least
two hours, provided the center is open at the time of the earthquake. Within a
day, therefore, most epicenters are determined as well as they will be in the
final analysis by someone on the web. Local networks, of course have the
advantage that if an earthquake is felt, they know about it immediately and
initial epicenters would usually be better than expected by teleseismic agencies.
There are some networks (like NORSAR) which issue teleseismic locations which
should never be used as they are simply too inaccurate. Accuracy is a big
issue and is addressed by checking the epicentral data every several hours
for the first day and then after a week taking the final solution.