Short Period

The CMG 40T-1sec seismometer looks, on the outside, just like the CMG 40T-30sec, intermediate period seismometer. Its response, however, is tuned to short-period signals (1-100Hz). One hundred of these feedback seismometers were purchased for the Flexible Array sensor pool.

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.

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This passive 1-Hz sensor is seldom used because there are not many in the EPIC fleet and they have essentially been replaced by the CMG-40T-1Hz feedback seismometers.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: 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