With sustained rains expected to continue, landslides on Mercer Island will become more likely.
In a typical year, the city will see between six and 15 landslides. The resulting damage can cost from a few thousand dollars (for smaller slides), to upwards of several hundred thousand dollars, not to mention personal injury.
Slides are typically triggered by excess water and most include a contributing human factor such as people discharging their roof drains onto slopes, removing vegetation from slopes or excavating into or placing fill onto slopes. Broken pipes underground can also be a problem.
Understanding and avoiding common contributory causes can effectively reduce landslide risk.