ANSS NAI - Draft model - 11/09/2000

This is the discussion of the draft model provided by Lind Gee and the Network Architecture and Interconnection Subcommittee of the Technical Integration Committee(TIC). These documents are drafts and will change as the various TIC subcommittees meet and refine the plans. The ANSS-MA will follow the standards outlined by these committees.

Diagrams such as this have been around for a number of years - I'm sure Ray Buland has stacks of them. I've seen a report by David Simpson in 1988 with something along these lines. More recently, Mitch Withers used a similar diagram in the model of Mid-America regional operations and I borrowed some of his nomenclature for this draft.

Please note - this is just a strawman in order to get us thinking. Nothing here is cast in stone.

First, some definitions and functionality.

Tier 0 - Station
The red and black circles indicate seismic stations. They may be any type of station - national, regional, or urban. Red indicates ANSS supported or funded stations, black indicates non-ANSS supported. The non-ANSS supported stations may be contributed for processing as the ANSS. The red lines indicate a communications link.

Some sites have multiple links - with secondary links indicated with dotted lines. These secondary links may be an alternate path to the primary recipient or a link to a neighboring processing center(s) (at any level). Not all stations have multiple telemetry links but some number of critical stations do. This diagram does not differentiate between dedicated and "dial-up" communications. Certainly many (most?) sites will require continuous telemetry, but noisy urban sites may not.

These sites will produce time-series data, either triggered or a combination of triggered and continuous data. In some cases, the dataloggers may output parametric data as well, such as state-of-health information, phase detections or peak ground motions.

Tier 1 - Data Concentrator
In some instances, data may be collected from several stations at a single site. These sites are denoted by yellow triangles and in Mitch's nomenclature, Tier 1 systems are called Data Concentrators. In general, these will be unstaffed facilities, but there may be a local contact. There are two possible models for Tier 1 systems. One is that these facilities just forward the complete waveform data to the next level. In this case, there may or may not be local storage at this site (assuming that the dataloggers have local storage), but essentially, the Tier 1 is a telemetry collection point. A second model is that some low-level processing is done at the facility and only selected waveforms are forwarded to the next level. In this case, a system might perform subnet triggering or something type of event detection and then forward the triggered waveforms (and associated parametric data) out. This type of model might be useful in areas where it is difficult to get sufficient bandwidth to transmit all of the waveform data.

These may or may not be ANSS-supported operations. In one example, this might be a local utility that has deployed strong-motion instrumentation and is willing to share the data. In another example, this might be data from a local array of stations, with a single, convenient point of outward communication.

Tier 2 - Local Center
This level is perhaps the least well constrained (or at least I have the most questions about its implementation). The center may be responsible for the operations and maintenance of a number of stations, as well as for local acquisition, under the direction of a regional center. Waveform data collected by the local centers will be forwarded to its regional center and to additional regional or national centers as needed.

By agreement with the regional processing center, the local center may run all or part of the earthquake processing software. The local center may perform review operations and local QC on data from their stations.

These facilities may provide local seismological expertise to the community and local technical support for operations at tiers 0 and 1. These are facilities staffed during normal hours of operation and in some cases may provide 7x24 response.

Tier 3 - Regional Center
The regional processing center is a central hub of operations in an ANSS region and there may be more than one in a region. If there is more than one regional center, within a region, the centers have specific areas of coverage.

The regional centers have primary responsibility for rapid earthquake processing and notification. While the regional center will receive parametric data from other tiers within its region - and from adjoining regions - it will be the authoritative source of earthquake information in its region and will have responsibility for distribution of this information.

They also have primary responsibility for building reviewed products, such as earthquake catalogs and QC waveform data. They may or may not have a local archive, but will contribute the waveform data collection to an ANSS data center.

Tier 4 - National Center
The national center (whose operations may be split among several facilities) is "the focal point for all seismic monitoring in the United States. ... It should serve ... as a backup for all regional networks and data centers. It must be able to replicate their services should a regional center fail due to a major earthquake, power loss, or other extreme event ...".

Questions/Issues/Stray thoughts (partial list ...)

Level Operations Staffing Products Rapid earthquake notification Seismological expertise Technical Support
0 Station - raw timeseries
auto parameters		 - - -
1 Data concentrator - raw timeseries
auto parameters		 - - -
2 Local 9-5 normally auto parameters
auto event information (?)
reviewed catalog (?)
QC waveforms (?)
 - X X
3 Regional 7x24 response auto parametric information
auto event information
reviewed catalog
QC waveforms
archive in some cases		 X X X
4 National 7x24 response auto parametric information
auto event information
reviewed catalog
QC waveforms
archive		 X X X

This page last modified 11/09/2000