Canadian Earthquake Early Warning

Earthquake Early Warning (EEW) is the rapid detection of earthquakes, real-time estimation of the shaking hazard, and notification of expected shaking. EEW provides seconds to tens-of-seconds of notice before strong shaking arrives, which can help reduce injuries, deaths, and property losses.

Natural Resources Canada (NRCan) has developed a national EEW system designed to provide early detection and warning in areas of moderate to high earthquake hazard and with concentrations of population and infrastructure. In Canada, this earthquake risk is concentrated in western British Columbia, eastern Ontario, and southern Quebec.

The EEW system began operation in British Columbia in the spring of 2024 and will begin in Quebec and Ontario in early 2025.

How EEW systems work

Earthquakes release energy that travels through the Earth as seismic waves. Seismic sensors detect the first energy to radiate from an earthquake, the P-wave, which rarely causes damage. The sensors transmit this information to data centres where a computer calculates the earthquake's location and magnitude, and the expected ground shaking across the region. This method can provide warning before the arrival of secondary S-waves, which brings the strong shaking that causes most of the damage.

Video: Earthquake Early Warning animation

Earthquake graphical respresentation (Transcript)

When an earthquake occurs, its (generally weak but fast) P-wave travels rapidly from the epicentre, triggering the EEW system which then alerts people and systems before the (slow but strong) S-wave arrives. These seconds to tens-of-seconds of warning allow people to protect themselves (usually to “Drop, Cover, and Hold on”) and systems to take protective actions, such as stopping trains.

EEW system alerts

EEW alerts are sent to the public through national alerting systems (e.g., the National Public Alerting System) and other means. Government Operations Centres and Critical Infrastructure Operators may use notifications to trigger automated responses to protect people and property.

The Canadian EEW system is designed to alert for potentially harmful earthquakes, including for strong shaking from earthquakes outside Canada's borders. NRCan is therefore working with the United States Geological Survey, using their software, and sharing data with them.

EEW systems provide up to tens-of-seconds of warning by detecting an earthquake immediately as it occurs; they do not predict earthquakes. In general, it is best to assume the shaking is imminent and take immediate protective actions.

Earthquakes generating only low levels of shaking will not produce EEW alerts. Within EEW coverage areas, public alerts will be sent for earthquakes estimated to be at or above magnitude 5, causing shaking at intensities of IV or greater.

Additionally, when an alert is received is dependent on several factors, including distance from the earthquake and how the alert is received. Sites very close to an earthquake's epicentre may be in the event's "late alert zone", within which alerts may arrive after the shaking.

EEW does not remove the need for other earthquake risk reduction, preparedness, and response measures, such as constructing to building code requirements.

Safe response actions

Earthquake Early Warning only reduces the impacts of strong shaking if people and systems take protective actions.

Recipients of an EEW alert should assume strong shaking is imminent. There are several protective actions people and organizations can take within seconds of notice. Some of these might be automated, in the case of critical infrastructure and other high-risk operations, triggering automated actions as shown below. For people, this is generally to Drop, Cover and Hold On.

Possible preventative measures include: