Earthquake Early Warning

In response to the need for enhanced earthquake safety measures for a busy tunnel, Weir-Jones successfully implemented the ShakeAlarm® system. This solution leverages cutting-edge seismic technology to preemptively close the tunnel during seismic events, minimizing risk for users and maintaining operational integrity in critical infrastructure.

The Problem

The client had a tunnel that carried a primary highway under a large river. The tunnel was built before modern seismic codes and rested on several hundred feet of river delta deposits. It was determined that this critical piece of infrastructure was at significant risk of collapse in a major seismic event. The client needed a way to mitigate the risk to the approximately 100,000 daily users of the tunnel and structural reinforcement was not a feasible approach. The decision was made that they required an earthquake early warning system that could shut down access into the tunnel before an event, hopefully with sufficient time for those already inside to exit.

The Procedure

Weir-Jones developed the ShakeAlarm® system to meet the client’s needs. This required high sensitivity borehole installed geophone sensors, a full 24bit data acquisition unit capable of interrogating up to 24 channels at 2000 samples per second, and a processing unit capable of running proprietary P-Wave detection and validation algorithms in a fraction of a second. The ShakeAlarm® platform that was developed met these specifications, is able to detect and analyze P-Waves to determine if the following S-Wave will be a danger, and issues an alarm only on threatening events.

The Conclusions

The client’s tunnel is now protected by a state of the art earthquake early warning system capable of automatically shutting down entrance into the tunnel based on P-Wave detection science.