British Columbia’s south coast school districts are responsible for hundreds of schools and for the safety of students, faculty and staff learning and working within them. Although early earthquake warning systems have been around for years, when a school board seeks to install the systems in dozens or even 100 schools, the systems’ cost becomes a concern.
A device made of strong motion detectors and designed by University of British Columbia (UBC) engineers a few years ago provides cash-constrained school districts with a basic solution. The systems—developed by civil engineers at the UBC’s Earthquake Engineering Research Facility—use off-the-shelf accelerometers that cost pennies each, detect vibrations and measure ground motion. Large numbers of low-cost accelerometers are assembled and configured to optimise the quality and sensitivity of the motion signals detected and measured.
As with most early earthquake warning systems, the devices designed for schools are calibrated to detect earthquakes’ compression (P) waves, which children may not notice and adults may ignore. Fast-moving P-waves, which rarely damage structures, may be mistaken for the rumbling of a heavy truck nearby. They precede a quake’s slower, damaging shear (S) waves—by just a few seconds or as many as tens of seconds, depending how far away the earthquake’s ground zero is.
Encased in plastic cylinders, the school devices are usually buried in pairs—each about 30 metres apart from its partner—and about two metres deep in a schoolyard. They connect to black boxes in the schools, and relay signals and measurements to powerful servers at UBC, where software monitors and analyses them. The system is calibrated to recognise and disregard tremors caused by construction, transport trucks or school buses. In actual earthquakes, it triggers alarms in the schools. This occurs within milliseconds and gives children, teachers and staff seconds to seek shelter beneath desks or in designated safe areas before the damaging S-wave arrives.
Earthquake Engineering Research Facility Director Dr. Carlos Ventura, P.Eng., presented information about the earthquake early warning system already implemented and operational in the province to the BC Liberal caucus and Opposition leaders during APEGBC’s recent meetings with the provincial government.
Read the original article in Innovation, March/April 2016
