Strong Motion Accelerograph – Gecko SMA-HR
The new Kelunji Gecko is at the core of our strong motion accelerographs. Perfect for structural health monitoring, the combined recorder and acceleration sensor can be fixed to a structure with a single central bolt. There are two variants available: the base model compact Gecko SMA and the high resolution Gecko SMA-HR.
The low-noise Gecko SMA-HR uses an integrated force feedback accelerometer providing an all-in-one package that continuously records data in a ring buffer so that when the earthquake eventually strikes you know you’ll have all of the data you need. Such high sensitivity enables the monitoring of the natural frequency and modal response of a structure. The Gecko SMA-HR is compliant with the 2015 DPWH guidelines on earthquake recording instrumentation for buildings. Continuous data is stored onto a local SD card and optionally telemetered to a remote computer via wireless modem or over Ethernet.
This SMA-HR is also useful for rapid deployment of aftershock monitoring networks – it has been field tested at temporary deployment stations to show that earthquakes as low as magnitude 1.0 are clearly visible at a range of 10km from the instrument, and earthquakes as small as magnitude 0.2 within 3km are also discernible above the typical background noise at a temporary surface station.
The lower cost Gecko SMA uses less sensitive MEMS technology accelerometers that are designed to detect large levels of ground motion that may cause structural damage. A magnitude 2.0 earthquake at 100km range might not be visible on a MEMS accelerometer, but with full scale ranges ±2g, ±5g and higher available you are certain to detect very large nearby events. Although the MEMS accelerometers are over 300 times noisier than the feedback accelerometer in the SMA-HR, they are only about 3 times noisier than a standard geophone but with a much greater full scale range, so the SMA can be used for near-field blast monitoring.