The noise floors for the three Trillium seismoemeters are shown in the following figure.

The Trillium 120 and Trillium 240 are well-suited to teleseismic studies, with the latter able to resolve the MLNM from 100s to 10 Hz.

Clip Levels

The clip levels of the Trillium family of seismometers are shown in the following graph. All of the sensors are capable of detecting an M6 event at 100 km epicentral distance without clipping.

The clip level of a seismometer always rises up at the lower corner period of the instrument. Unfortunately this is of no practical use, because there is no energy in a typical local or regional event below 10 s period and because teleseismic events above M8 are so rarely observed. The clip level of the Trillium 120 and Trillium 240 begins to fall off above 1.5 Hz, taking advantage of the fact that the spectral content of a typical local or regional event does too.

The graphs above do not tell the whole story. Because performance is fundamentally limited by existing 24-bit technology, this must be taken into consideration at the same time as you select your seismometer.

The following pages discuss digitiser configurations for each of the three Trillium seismometers.