Broadband Seismograph

What makes a seismograph "broadband"

"Broadband" describes the range of frequencies a sensor can detect, which depends on its design. Short-period seismometers output a consistent amplitude at 2 Hz and above but lose accuracy below that; medium-period sensors stay linear down to about 0.016 Hz (a 60-second period) but tend to lose linearity above 100-200 Hz. Long-period, or broadband, sensors are linear from a 120-360 second period up to 50-100 Hz, letting them capture most global and local earthquakes, provided their self-noise is low enough across that band.

Some cheaper sensors claim very long periods but have high self-noise, which limits them to detecting only high-amplitude signals - making them impractical for some research applications.

Digitiser

The Kelunji Gecko seismic data logger is compatible with any seismic sensor on the market. It samples at a user-configurable rate from 40 to 4000 samples per second and stores data continuously as miniSEED files to an SD card, with GPS-synchronised timing. It is available as the low-cost Gecko Compact, the waterproof Gecko Rugged, and variants that integrate sensors, backup batteries and communications systems.