INL Seismic Stations
The INL operates 27 seismic stations that are located on and around the Snake River Plain in southeastern Idaho. The seismic stations continuously record seismic signals generated by earthquakes and other sources. The seismometers are very sensitive and can pick up vibrations in the ground due to earthquakes from around the world, local earthquakes that occur in Idaho, and cultural noise such as footsteps, vehicle motions, windstorms, and sonic booms.
An INL seismic station is composed of one or three short-period velocity sensors (seismometers), a digital data acquisition system, a digital signal transmitting system, remote power sources (such as batteries, solar panels, and wind generators), and, in some cases, other instrumentation.
Single-component seismic stations have vertically oriented seismometers that are a Mark Products model L-4C or Teledyne Geotech model S-13. Eleven seismic stations located within the Snake River Plain have their vertical-component seismometer located at the bottom of 18 m (65 ft) or greater borehole to help dampen wind and cultural noise. Stations within the Basin and Range have seismometers buried to a maximum depth of 3 m (10 ft) below the ground surface near rock or are installed on rock outcrops. Five seismic stations also have two horizontally oriented sensors that are Teledyne Geotech model S-13 seismometers, which are located within concrete vaults. Other instrumentation at the seismic stations may include a GPS antenna and receiver or a tri-axial accelerometer.
The seismic signals are digitized by a DAQSystems NetDAS field recorder at the seismic station then transmitted to the INL Research Center in Idaho Falls, Idaho. The NetDAS has an embedded LINUX computer, a Symmetric Research 24-bit digitizer, and its own GPS clock. It digitizes data and time stamps the data with accuracies greater than 0.001 seconds. INL uses four and eight-channel NetDAS recorders that boot from flash memory, providing high reliability and low power consumption. The NetDAS has nearly 22 bits of data resolution over ± 20 volts for a four-channel unit or ±10 volts for an eight-channel unit.