A debris flow is a liquid landslide with more soil, rock, leaves, and sticks than water. It can travel faster than a person can run and can carry boulders as large as a van. Large debris flows can destroy bridges, roads, and houses.
Debris flows are most often triggered during heavy, constant rainfall. Gullies and ravines are particularly susceptible to debris flows.
Risk of debris flow on the North Shore: High
The mountainous terrain and wet weather put the North Shore at high risk of a debris flow.
How to prepare
Know the signs of a debris flow and make a household emergency plan in case you need to evacuate.
If you notice any of the following conditions, evacuate immediately and phone 9-1-1:
- Rapid water or slurry flow, where it has not been observed before
- Irregular or suddenly stopped stream flow
- Cracking or falling trees, particularly in the absence of strong winds
What to do during a debris flow
If your house is in immediate danger, evacuate. When evacuating:
- Check to ensure that bridges and culverts along the escape route are still in place
- Use caution when crossing creeks. Do not cross a creek if it has blocked your escape route
- Drive slowly, particularly at night, as roads could be covered with excess water, mud, and debris
If driving is unsafe, a water-based evacuation may be an alternative option.
- Grab-and-go kit
- Prepare a vehicle emergency kit