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UL Network
SEED Conventions

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.

Region Prefix
SEED station prefix Region
AKAlaska
CAMiscellaneous CA sites
HIHawaii
LVLong Valley, CA
OROregon
PKParkfield, CA
SCSouthern California
SFSan Francisco, CA
SJSan Juan Bautista, CA

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.

Experiments
SEED Location Experiment Primary data channels Auxiliary data channels
Cn Creepcreep(1-n channels)rainfall, temp, voltages
Mn Magnetometermagnetic field (1-3 channels)temp, voltages
Tn Tensor strainstrain (3 channels)pore pressure, rainfall, voltages
Vn Volumetric straindilatation strainpore pressure, barometric pressure, temp, voltages, water level
Sn Wire strainstrain (3 channels)temp, voltages
An Tilttilt (2 channels) temp, rainfall, voltage
Ln Lake level tiltwater tilt levelbarometric pressure, temp, voltages, wind speed, wind direction
In Long baseline tiltinterferometer tilttemp, voltages
Wn Well waterwater levelsgravity, barometric pressure, rainfall, temp, voltages
Qn Electric potentialelectric potential

SEED Channel convention for the UL network

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. The following table describes the various SEED channels names used by the UL network.
SEED Channel Description
RA1 LCD
RA1 Low Count
RA2 High Count
RA2 LCD 2
RA6 LCD
RA7 LCD 2
RAF Tilt - Longbaseline Tiltmeter
RAR Tilt Orthogonal Component
RAT Tilt Parallel Component
RAX Tilt Meter x
RAY Tilt Meter y
RB1 Creep Measurement 1
RB2 Creep Measurement 2
RBE Creep East Distance Between Rod And Piers
RBH Creep High Gain Response
RBL Creep Low Gain Response
RBT Differential Temperature Signal
RBW Creep West Distance Between Rod And Piers
RD1 Atmospheric Pressure 1
RD2 Atmospheric Pressure 2
RD3 Pore Pressure 1
RD4 Pore Pressure 2
RD5 Atmospheric Pressure 1
RD6 Inverse Barometric Pressure
RE1 Battery Voltage 1
RE2 Battery Voltage 2
RE3 Downhole Voltage 1
RE4 Raw Voltage
RE6 Uphole voltage
RE7 UPS Voltage 1
RE8 Zener Voltage
RE9 Ground Voltage
REG Ground Voltage
REI Battery Voltage 1
RF1 Magnetic Field x Direction
RF2 Magnetic Field y Direction
RF3 Magnetic Field z Direction
RFI Total Magnetic Field
RHS Soil Moisture
RK0 Temperature
RK1 Downhole Thermistor 1
RK2 Downhole Thermistor 2
RK3 Downhole Thermistor 2
RK3 Uphole Thermistor
RK4 Water Temperature
RK5 Downhole Thermistor 3
RK6 Downhole Thermistor 4
RKI Temperature
RR1 Rainfall
RS1 Strain Component 1
RS2 Strain Component 2
RS3 Strain Component 3
RS4 Strain Component 4
RSI Laser Measurement Longbaseline Tiltmeter
RV1 Volumetric Response
RV2 Volumetric Response Amplified x10
RV3 Volumetric Response Amplified x50
RV4 Deformation of the sensing volume (high gain)
RV5 Deformation of the sensing volume (low gain)
RV6 Displacement of the volume of fluid
RY1 High Resolution Water Measurement 1
RY2 High Resolution Water Measurement 2
RY3 High Resolution Water Measurement 3
RY4 Low Resolution Water Measurement 1
RY5 High Resolution Water Measurement 1
RY5 Low Resolution Water Measurement 2
RY6 Water Depth
RY8 High Resolution Water Measurement 4

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

Waveform data from the UL network are available in SEED format. Several tools provide access to SEED format data at the NCEDC, both in terms of querying the archives and allowing data requests.

Help on using these tools is available.

First-time users:

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.