Sensors

Salient Features: This 3-channel sensor has a frequency of 2.0Hz, damping of 0.707 critical and sensitivity of 88V/m/s. Best used for (but not limited to) measuring local earthquakes, teleseisms, and some active source. Types of Projects include: determination of site response, determination of crustal structure, volcanic studies, aftershock studies, and glacial studies. Manufacturer Documents:

Link to Sercel seismometer page

Salient Features: Flat response to velocity from 120 seconds to about 10 Hz Low power Installation Tips: Example of STS-2/RT130 Setup One-pager field sheet

  Troubleshooting Tips: If you cannot center the masses of even one of the 3 elements of the STS-2, all your data could be compromised. The document provided here will guide you to a 'manual' process for attempting to get those masses centered, IF and ONLY IF the masses do not center after repeated (a dozen tries) centering commands.  

Nanometrics Trillium 240

The Nanometrics Trillium 240 is a symmetric triaxial broadband instrument that has a flat response to ground velocity between 240s and 200Hz, and has a low self-noise, below the New Low Noise Model between 100s and 10Hz.  The manufacturer specifications of operating temperatures are between -20C and +50C, but the Trillium 240 has operated reliably for us to temperatures below -60C.  The power consumption at low seismic noise conditions and with the instrument well leveled is about 650mW.  The Trillium has a +/-1deg tilt tolerance, is fairly sensitive to varying temperature, but was designed to be insensitive to atmospheric variations.

The Trillium 240 is well suited for medium to long term experiments in the Arctic and Antarctic supported by the EarthScope EPIC Polar Program.

Salient Features 30sec to 50 Hz flat velocity response Manual Mass locking/unlocking Remote Mass Centering Response Characteristics:

Necessary information:

Sensor: sensitivity and passband (velocity transducer) or scaling (accelerometer)

For information on sensor sensitivity and passband, see the Sensor Comparison Chart along with the Sensor Response Plot.

Datalogger: Analog-to-Digital (A/D) conversion factor (aka bit weight) and Gain 

Quanterra model Q330: 419,430 counts/volt, or 2.384 uV/count at a Gain of 1 RefTek model RT130: 629,327 counts/volt, or 1.58997 uV/count at a Gain of 1

 

Example: Counts to Ground Velocity Conversion within the Passband

 

Instrumentation to support portable seismology available from the EPIC:

Dataloggers - This section encompasses the equipment which take in data and stores it on some type of non-volatile media.

Power Systems - All the required equipment to keep a seismic station continuously powered throughout its deployment.

Sensors - The equipment that actually detects and quantifies ground motion. The sensor sends this information to the datalogger through a cable.

EPIC Accelerometers: Kinemetrics FBA-2 Episensor Features:

Strong-motion sensors are accelerometers, and are designed to measure the large amplitude, high-frequency seismic waves typical of large local earthquakes. These seismic waves result in the strong ground motion we feel during a large earthquake. Strong ground motion is often to blame for the structural damage that occurs during an earthquake. The data seismologists record with strong motion sensors is used to improve the design of earthquake resistant buildings and to understand earthquake-induced geologic hazards like liquefaction and landslides. The range of motions of interest for strong-motion applications includes accelerations from 0.001 to 2 g and frequencies from 0 to 100 Hz or more.