Stephenson Probe

Stephenson Probe

Developed by Bill Stephenson from GNS Science, the Stephenson Probe is a novel subsurface strong-motion accelerometer module intended to sense the shaking of the ground under soft soil sites during strong earthquakes. The process of installing the instrument provides a profile of how ground conditions vary with depth.

This non-recoverable triaxial strong-motion instrument combines the attributes of similar but larger and more costly accelerometers, with the low-cost installation method of penetrometry. The dominant cost of traditional subsurface recorders lies in their installation: a hole must be drilled and cased before clamping the accelerometer to the casing. However, a sufficiently small package – such that of the Stephenson Probe– can be directly pushed deep into soft soil until it lies on the hard substrate. Installation costs are cut by an order of magnitude compared with drilling and casing.

The Stephenson Probe is an economical solution for investigating site effects on earthquake shaking at relatively shallow, soft-soil sites. Analysing the site conditions with this new instrumentation enables engineers to design structures that mitigate the effects of earthquakes in a more cost-effectively manner.

For further information on the Stephenson Probe, contact:

Hannah Brackley (Business Development Coordinator):