Data Services Newsletter

Volume 6 : No 3 : December 2004

Virtual networks becoming a reality at the DMC

The virtual network concept is increasingly being integrated with the DMC’s data query and request tools. For an introduction to virtual networks see the Feature article of Volume 6, Number 2, June 2004 of this newsletter. To summarize the concept, virtual networks allow stations to be arbitrarily grouped regardless of their network affiliation. The following virtual networks are currently defined:

VNET Code Definition
_ANSS Advanced National Seismic System stations
_FDSN FDSN network stations
_GSN Global Seismograph Network stations
_US-ALL All USArray (EarthScope) stations
_US-BB USArray Permanent Array/Backbone stations
_US-TA USArray Transportable Array stations

The Transportable Array component of USArray is an ideal example of where a virtual network definition is applicable. The Transportable Array is currently composed of stations from 4 different networks that would otherwise be difficult to group together, by using the _US-TA definition these stations can all be selected together.

Current state of the USArray network in December 2004
Figure 1: Current state of the USArray network in December 2004. Figure courtesy of the Array Network Facility.

Tools at the DMC that now support virtual networks as selection criteria include SeismiQuery, BUD Tools, WilberII, BREQ_FAST (including WebRequest) and NetDC. The SeismiQuery information queries for ‘channels’ and ‘stations’ have been updated to allow selection based on virtual networks. Additionally, a new ‘virtual nets’ information query has been added specifically to return information about defined virtual networks; a snapshot of this new interface is here:

Virtual networks access in SeismiQuery
Figure 2: Virtual networks access in SeismiQuery.

The BUD Tools

BUD Query Interface, BUD Monitor and BUD Stat all allow selection based on virtual network codes. Here is a snapshot of the current BUD Query Interface, notice the Virtual Net pull-down list:

Virtual networks access in BUD
Figure 3: Virtual networks access in BUD.


WILBERII has also been updated to allow data selection based on virtual networks: Support for virtual networks will continue to be integrated into the DMC’s systems.

by Rick Benson and Tim Ahern (IRIS Data Management Center)

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