UL Network
SEED Conventions

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Dataset Description

The USGS Low-Frequency Geophysical dataset is comprised of timeseries data from a number of different types of experiments at various sites. Each experiment consists of one or more primary data channels (such as creep measurements) as well as other related state-of-health or environmental measurements (such as temperature, barometric pressure, and voltage measurements from various testpoints on the acquisition system or sensors).

The original USGS dataset was organized into individual channels of timeseries data. Each data channel had a unique 4 character case-sensitive name. For distribution at the NCEDC, the dataset was organized into the UL network and converted to the SEED format (Standard for the Exchange of Earthquake Data).

SEED channel identifiers

In the SEED system, each channel of data is described by 4 identifiers:

1. SEED Network code

A 1-2 character string, often named for the type of data or the organization that operates the sites and collects the data. The SEED network code for the the entire USGS Low-Frequency dataset is UL.

2. SEED Station code

A 1-5 character string for the geographical site.

3. SEED Location code

A 2 character string, which is used by this network to classify the experiment. The first character is used to identify the type of experiment. The second character is the experiment number, since several sites have multiple instances of the same type of experiment (such as multiple strain meters at a single site).

4. SEED Channnel code

A 3 character string which describes the type of data channel. The SEED channels name attempts to encodes data rate, instrument type, and orientation. The SEED channel naming convention is described in the SEED Manual Appendix A.

SEED Station convention for the UL network

The SEED station name is a 1-5 character string that names the geographic site. The UL network uses the first 2 characters to define the region, and the last 3 characters as a mnemonic name within that region. The following table describes the region prefix of the SEED site names.

SEED Location convention for the UL network

The SEED location code is used by the UL network to identify the experiment. The first character is used to identify the type of the experiment. The second character is the experiment number, since several sites have multiple instances of the same type of experiment, such as multiple strain meters at a single site.

SEED Channel convention for the UL network

See the SEED channel assignments for the UL network data channels for a complete mapping of the original USGS channel names to the SEED data channel names.

Data Access

• Querying the archives
  • SeismiQuery at the NCEDC
  • NetDC Request Form
• Requesting data
  • NetDC Request Form

Help on using these tools is available.

First-time users:

• Use the SeismiQuery program to check on the availability of UL digital waveform data.
• Use the NetDC Data Request Form to request digital waveforms from the NCEDC in SEED format or to check the availability of the UL digital waveforms.
• Use the RDSEED program to read the resulting SEED files.

The timing accuracy of the UL data is limited by characteristics of the data acquisition system system. Please read the description of the data timing carefully before you use the data.

A cleaned version of the USGS data is available from the USGS.

Northern California Earthquake Data Center 215 McCone Hall, UC Berkeley Berkeley CA 94720-4760 www@ncedc.org

Copyright 1995-2005, The Regents of the University of California.
Last modified: Mon Dec 17 17:31:07 PST 2007