Why did only some people in B.C. get an earthquake alert? Federal agency explains

Millions likely felt the shaking during a moderately sized earthquake on B.C.'s South Coast Friday.

When a strong earthquake struck B.C.‘s Sunshine Coast northeast of Sechelt Friday afternoon, Canada’s Earthquake Early Warning system sent an alert.

“Earthquake detected!” reads the message sent to cellphones at 1:26 p.m.

“Drop, Cover, and Hold on. Protect yourself.”

Across Metro Vancouver, some 100 kilometres or so southeast of the quake’s epicentre, residents felt the shaking, but only some of them got the alert notification.

According to Natural Resources Canada, that’s by design.

“The Earthquake Early Warning system is designed to alert areas that will receive strong shaking, which could cause harm,” the federal agency said in a statement.

“In this case, the alert was intended for people within the red polygon on the map below. People outside this area shouldn’t have expected an alert, but some did receive the alert, because their device was connecting to a cell tower within the EEW area.”

Shaking from the quake – which Earthquakes Canada says registered magnitude 4.7, down from a previous estimate of 5.1 – was lightly felt as far away as Prince George, according to the agency’s website.

CTV News has also heard from Kelowna residents who were surprised to feel a light shaking Friday afternoon.

Bill Forbes, who lives outside the Vancouver Island community of Qualicum Beach – an area outside the EEW zone – said he received the emergency alert shortly after the shaking stopped.

The timing made him wonder if the system was not working properly.

Friday’s quake prompted an “immediate inspection” of Vancouver’s bridges, performed by structural engineering consultants, the city said in a bulletin.

BC Ferries temporarily halted service at the Horseshoe Bay and Langdale terminals, for similar inspections of the infrastructure.

Earthquakes Canada says it has not received any reports of damage from Friday’s incident.