Tsunami Preparedness

Tsunami Preparedness

The City of Prince Rupert and our emergency personnel work to ensure that residents and community stakeholders have the necessary information to inform our collective response to emergencies such as tsunami warnings.

Between 2017 – 2019, the City of Prince Rupert oversaw a contracted study of the risk posed by potential tsunamis to our community that addressed the following:

  • Identification of seismic and non-seismic tsunami hazards (earthquake and landslide)
  • Flooding analysis for most likely and worst tsunami hazard cases
  • Analysis of vulnerability
  • Assessment of hazard likelihood
  • Risk assessment
  • Consideration of the effects of future climate change
  • An assessment of community resilience

The study found that in all types of tsunami event (seismic and non-seismic), Prince Rupert’s residential areas were not considered to be at risk of inundation/flooding. Given that information, the City recommends that in the event of a tsunami warning, residents stay in their homes, and under no circumstances leave Kaien Island or go to the waterfront. Traffic during an emergency, especially surrounding the hospital, can prevent people who are injured or need medical attention from getting it - please stay at home unless you need emergency attention

The study also confirmed the safety of the City’s two emergency evacuation centres, listed below:

Primary Evacuation Centre

Prince Rupert Recreation Complex

1000 McBride St,

Prince Rupert, BC

V8J 3H2

 

Secondary Evacuation Centre

Charles Hays Secondary School

201 Prince Rupert Blvd,

Prince Rupert, BC

V8J 3W1

 

Subscribe to Localized Emergency Alerts

The City’s emergency alert system provides voice alerts to landlines, text message alerts to mobile users, as well as email alerts to subscribed residents and visitors in case of a local emergency.  As emergency personnel gather more information during an emergency, real-time updates can be provided directly to subscribers regarding local conditions and instructions. This program complements the Provincial Alert System by providing residents more context and information on local emergency conditions. If you haven’t signed up already, you can subscribe yourself and family members at: www.princerupert.ca/emergency. Once subscribed, you will receive a message confirming you've been registered.

Please note - due to privacy restrictions, this is a subscription based service. You MUST subscribe in order to receive alerts. Please share this information widely among friends and family.

 

Levels of Tsunami Alert

Not sure what it means when you get an alert about tsunamis? See below for the different alert levels and what they mean:

Tsunami Warning – A tsunami warning is issued when a tsunami with the potential to generate widespread inundation is imminent, expected, or occurring. Warnings alert the public that dangerous coastal flooding accompanied by powerful currents is possible and may continue for several hours after initial arrival. Warnings alert emergency management officials to take action for the entire tsunami hazard zone. Appropriate actions to be taken by local officials may include the evacuation of low-lying coastal areas and the repositioning of ships to deep waters when there is time to safely do so. Warnings may be updated, adjusted geographically, downgraded, or canceled based on updated information and analysis.

Tsunami Advisory – A tsunami advisory is issued when a tsunami with the potential to generate strong currents or waves dangerous to those in or very near the water is imminent, expected, or occurring. The threat may continue for several hours after initial arrival, but significant inundation is not expected for areas under an advisory. Appropriate actions to be taken by local officials may include closing beaches, evacuating harbors and marinas, and repositioning ships to deep waters when there is time to safely do so. Advisories may be updated, adjusted geographically, upgraded to a warning, or canceled based on updated information and analysis.

Tsunami Watch – A tsunami watch is issued when a tsunami may later impact the watch area. The watch may be upgraded to a warning or advisory or canceled based on updated information and analysis. Emergency management officials and the public should prepare to take action.

Tsunami Information Statement – A tsunami information statement is issued when an earthquake or tsunami has occurred of interest to the message recipients. In most cases, information statements are issued to indicate there is no threat of a destructive basin-wide tsunami and to prevent unnecessary evacuations. Information statements for distant events requiring evaluation may be upgraded to a warning, advisory, or watch based on updated information and analysis.

A cancellation is issued after an evaluation of water-level data confirms that a destructive tsunami will not impact an area under a warning, advisory, or watch or that a tsunami has diminished to a level where additional damage is not expected.

 

Earthquake Generated Tsunamis

The City's study provided significant information regarding the risk of earthquake generated tsunamis, which are those that we are likely to experience primarily when there is a regional earthquake in the Alaska/Aleutian or Cascadian subduction zones. As previously mentioned, the study found that in earthquake related tsunami events, Prince Rupert’s residential areas were not considered to be at risk of inundation/flooding. In addition, it found:

“Emergency services, critical community infrastructure and schools are all located away from the impacts of these tsunami scenarios. All road transportation corridors, BC Hydro corridors and substations, and the municipal water supply are outside of tsunami impact areas.” (pg. 5, City of Prince Rupert Tsunami Flood Risk Assessment – Final Report)

Although the study found Prince Rupert was not likely to have inundation greater than 2 metres at the waterfront in the case of earthquake generated tsunamis, there remains risk to waterfront assets and shoreline workers from wave run-up and fast moving water. These risks to different assets were provided in the Risk Assessment (Appendix F), alongside basic recommendation for evacuation of key waterfront areas. Due to their proximity to the waterfront, the marine assets listed below do face risk of inundation of up to 2 m (but rarely more), as well as impacts from high velocity water (up to 4 m/second) flowing past their facilities and potentially dislodging/damaging assets like ships, logs, and other infrastructure. These estimates are the 'worst case scenarios' based on multiple scenarios modelled, taking into account tidal and climate impacts. Risks have been shared with waterfront based organizations so that they can integrate any new information into their emergency planning efforts. Again, the City recommends that in the event of a tsunami warning, residents stay in their homes, and under no circumstances leave Kaien Island or go to the waterfront, and that shoreline workers follow appropriate evacuation procedures as laid out by their respective employers.

 

Landslide Generated Tsunamis

The study also identified two slopes in the Prince Rupert area that may present a risk to the community of a landslide-generated should a slide occur. However, a full Risk Assessment for landslide based tsunamis was not conducted as there was insufficient geotechnical information available from which the probability (or likelihood) of a landslide could be determined.  Review of the available information on the slopes suggests there is a very low likelihood of a slide, but there is not at present enough information to conclude a slide is impossible or of such a low likelihood that it is not a credible threat.

Tsunami modelling was undertaken to understand the potential hazard that a slide might pose. Results provided in the Appendices of the study show that a tsunami generated slide could pose a major hazard to some areas of the community and surrounding area if it were to occur. More study (geotechnical) is recommended to better understand the potential likelihood of a slide so as to inform a risk assessment of the hazard.

 

Tsunami Study

Below are links to the final report provided by our contractors. This information has informed updates to the City’s Emergency Response Plan, and has been provided to the Prince Rupert Port Authority and associated waterfront stakeholders.

Tsunami Study

Appendices:

Appendix A – Landslide Source Evaluation

Appendix B - Digital Elevation Model Development

Appendix C – Numerical Modelling of Seismic Generated Waves

Appendix D – Numerical Modelling of Landslide Generated Waves

Appendix E – Seismic Tsunami Flood Maps

Appendix F – Prince Rupert Risk Assessment

Appendix G – Landslide Tsunami Flood Maps

 

Additional Information and Resources

Prepared BC https://www2.gov.bc.ca/gov/content/safety/emergency-preparedness-response-recovery/preparedbc

NOAA Tsunami Monitoring System (for Alaska based earthquakes) https://tsunami.gov/