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For approximately the last decade, the Harvard CMT project has determined nearly real-time CMT solutions in addition to the standard CMT catalog. Initial hypocentral information for this Quick CMT analysis is derived from the NEIS alerts posted by the USGS immediately following most large earthquakes. Seismic records from selected stations are obtained by Harvard via continuous Internet connections to the LISS server of the Albuquerque Seismological Laboratory and to the NRTS server of Project IDA . Data are also obtained from the IRIS SPYDER system. The typical data set available for analysis within a few hours after an earthquake consists of seismograms from about 50 stations of the Global Seismographic Network (GSN).
Quick CMT results are typically posted within a few hours after large
earthquakes. Quick CMTs are available on the web, via the
CMT catalog search,
and are distributed via email. If you would like to be included in
the Quick CMT distribution list,
send us email.
A map of recent Quick CMTs is updated daily.
Data for quick CMT processing are acquired from several sources. At the current time, the quick CMT project relies primarily on data transmitted continuously via the Live Internet Seismic Server (LISS) at the Albuquerque Seismological Laboratory, USGS, and the Near Real Time System (NRTS) of the Project IDA group at Scripps. Data are also obtained from the IRIS DMC after their retrieval by the SPYDER system.
Data acquired via LISS and NRTS are archived at Harvard until standard day volumes are available. The plots below show data holdings in the Realtime Seismogram Data Base (RSDB) for the past several days, as well as for several recent months.
Meredith Nettles, Department of Earth and Planetary Sciences, Harvard University, copyright ©2000, all rights reserved