Sensors

  Salient Features: This 3-channel sensor has a frequency of 4.5Hz, is critically damped at .707 and has a sensitivity of 32 V/m/s. Used for (but not limited to) active source (land and off-shore excitations), glacial movements, local earthquake and aftershock studies. Manufacturer Website: http://www.geospace.com/ EPIC Documents: Connector wiring information here Installation & Troubleshooting Documents: Y-28 Orientation and Installation Tips here One-pager field sheet

Sensor Manufacturer Power Corner
Frequency Damping Sensitivity Poles and Zeroes               STS-2 Streckeisen 30 ma @ 12vdc 0.0083 Hz 0.707 critical 1500 v/m/s *Depends on generation:

EPIC Intermediate-Period Sensors: Guralp CMG3-ESP Guralp CMG40T Nanometrics Trillium40 Features:

The low-period corner is 30 seconds for the 3 Guralps and is 40 seconds for the Nanometrics sensor. All are 3-component feedback sensors. The CMG40T and Trillium40 masses do not lock. One should still ship and handle them with care so as not to damage them. The CMG3-ESP has masses that require manual locking and unlocking.  For information on the CMG40T with corner-frequencies of 1-sec, click here.

 

Salient Features:

The Kinemetrics EpiSensor force-balanced accelerometer is a uniaxial surface package designed primarily for structural engineering applications. However, it can be used in a variety of applications for measuring accelerations up to ±4g and down to the ambient noise level. With full-scale recording ranges of ± 0.25 to ± 4g (user selectable) the EpiSensor provides on-scale recording of earthquake motions even at near-fault locations and in a wide variety of structure types.

EPIC Short-period Sensors: Sercel  L-22 Guralp CMG-40T-1 Features:

Short-period sensors are rugged three-component seismometers that cover the frequency band from 1 Hz to 100 Hz. These sensors are used in both passive and active-source experiments. EPIC's short-period sensors can be either feedback seismometers requiring power or conventional, passive seismometers requiring no external power.

EPIC Passive High-Frequency Sensors: 4.5 Hz 3-channel geophones (Sercel L-28-3D or GeoSpace Y-28/GS-11-3D) 4.5 Hz vertical geophones for Texan or Multi-Channel Digitizers 40 Hz vertical geophones for Texan or Multi-Channel Digitizers See also All-In-One Systems (Fairfield Nodes, SmartSolo) Features:

Teledyne Geotech S-13 Short Period Sensor

This passive 1-Hz sensor is seldom used because there are not many in the EPIC fleet and they have essentially been replaced by the CMG-40T-1Hz feedback seismometers. Information about S-13's from the old website can be found here.

The S-13's are heavy and awkward. The three components are separate units (about 20lbs each). They have strong magnets (passive seismometers), so they require about 12-inch spacing between each component.

Mark Products L-4C

 EPIC has very few of these 1-Hz passive seismometers, and does not have plans to replace parts that fail. Thus, they are likely to be discontinued, as they are cannabalized for spare parts and lost to attrition. Information from the old website can be found here and the cable drawings can be found here.

Salient Features:

EPIC owns two types of 40Hz vertical geophones.

The 40Hz geophones for the Multichannel Digitizer Systems are manufactured by Sercel and Geospace.  These vertical geophones are critically damped at 0.555 and have a sensitivity of about 21 V/m/s. The 40Hz geophones for the Texan Digitizers these geophones are manufactured by Sercel.  These vertical geophones are critically damped at 0.555 and have a sensitivity of 35.3 V/m/s

Uses primarily include active source studies.

Salient Features These single component geophones are available as vertical units for use with the Texan digitizer and as vertical 6-channel strings for use with the multi-channel digitizer systems.  The multi-channel strings are rarely used. This single channel vertical geophone has a frequency of 4.5Hz, damping of .707 critical and a sensitivity of 100 V/m/s. The primary use of these geophones is for active source experiments. Manufacturer Documents: EPIC’s 4.5Hz, vertical geophones were manufactured by Geospace under part number GS-11D. Installation & Troubleshooting:

 Installation requires a separate bubble level to be placed on top of the geophone for proper leveling.