Geoscience Reference
In-Depth Information
The IRIS DMC mission is accomplished by creating a data management system
suitable for archiving and processing of requests. This is enabled by providing the
hardware and software infrastructure that includes a StorageTek Powerderhorn tape-
based silo with a capacity of 1.2 petabytes, as well as currently keeping all data in an
online RAID (redundant array of independent disks) filesystem to enable fast access.
The policy employed is that 4 copies of the data are archived, including off-site
copies, creating a redundant, fail-safe environment, and data are transcribed to new
media every 4 years to keep technology current, and acts a read-back mechanism
that provides a periodic verification of the holdings.
Since 1992 the quantity and diversity of data managed by the IRIS Data Man-
agement System continues to grow exponentially. The DMC currently (2007) man-
ages data from 96 different permanent seismic networks, primarily in real-time,
around the globe, and manages data from more than 165 temporary experiments.
For the current, dynamic list of FDN approved network codes that shows current
data availability at the DMC, refer to http://www.iris.edu/mda. Permanent networks
includes the IRIS Global Seismographic Network (GSN), the International Fed-
eration of Digital Broad-Band Seismograph Networks (FDSN), and regional net-
works that contribute data to the IRIS archive or have open access to their data
sets.
The primary function of the IRIS DMC is to archive and disseminate digital
seismic data from modern instruments that began recording earthquakes after 1980
(Ahern 2003). In 2004, the IRIS DMC began hosting the SeismoArchives, which
consist of scanned seismic data recorded by the older instruments from the 1880s
to 1980, i.e., a period of about 110 years during which seismograms were recorded
on papers and microfilms. This activity is in collaboration with the International
Association of Seismology and Physics of the Earth's Interior (IASPEI) and the
U.S. Geological Survey. Others are encouraged to collaborate as well.
5.2 Contents of the SeismoArchives Online
A stack of seismograms in the form of scanned raster-image files is not easy to
use for research unless the seismograms can be quickly collated, viewed, and have
some supporting documentation and metadata available. Technology has existed
for the past decade to scan analog seismograms and related materials (e.g., maps,
field notes, papers, and reports) into computer readable files, and the World-Wide
Web provides easy access to these files online via the Internet. SeismoArchives at
the IRIS DMC (http://www.iris.edu/seismo/) leverages modern information technol-
ogy for archiving and disseminating historical seismograms and related materials.
At present, there are 4 major sections: (1) Archives by Individual Earthquakes,
(2) Archives by Stations, (3) Archives by Special Projects, and (4) Background
Materials.
Each individual earthquake archive (http://www.iris.edu/seismo/quakes/) con-
tains seismograms as well as supporting materials and links to appropriate files (if
Search WWH ::
Custom Search