SEATTLE — Did you know that most landslides occur between the months of December and March? And that 86 percent of landslides are caused to some extent by human activity? Landslide season is upon us and although the Seattle rainfall is currently below the landslide threshold, the City of Seattle is urging residents to take preventive measures to protect themselves and their property from possible landslides.
During the 2010/2011 landslide season, nearly 100 landslides were reported in Seattle.
Landslide experts agree there is not one single factor that contributes to the amount of slides in the area, but with last year’s La Nina type weather conditions – the wet and cold weather saturated the soil and greatly reduced slope stability.
With 20,000 Seattle properties (mostly residential) in landslide-prone areas, the City of Seattle and the Take Winter By Storm campaign encourage property owners to take preventive measures to protect themselves from landslides by attending the last 2011 City of Seattle Landslide Awareness Meeting on Saturday, Nov 12.
The free landslide awareness meeting will give the public the opportunity to consult with public/private landslide experts and learn simple preventive measures that will help protect them from future landslides, such as the following:
- Checking downspouts; making sure they are functioning/routed to a safe location
- Inspecting sloping areas for indications of slope movement and erosion
- Keeping fill and yard waste off slopes
- Shutting off the irrigation system and checking it out seasonally
- Leaving tree stumps in the ground on slopes
2011 City of Seattle Landslide Awareness Meeting
The landslide awareness meetings will include a presentation that discusses the causes of landslides, proper drainage for sloping sites, and vegetation maintenance on slopes. The presentation will be followed by a question and answer session and time for one-on-one discussions with professionals in the field, including the City of Seattle, The American Society for Civil Engineers, The Association of Engineering Geologists, The International Society of Arboriculture, and Associated Building Contractors.
Nov. 12 – 10:00 a.m. to Noon
South Seattle Community College
Judge Warren & Nobie Chan Education Center
6000 16th Ave. SW (across from the north parking lot)
The landslide record that was documented in the Seattle Landslide Study indicates that 86 percent of landslides that have occurred in the city have some human influence such as excavating and filling on steep slopes, broken pipes and uncontrolled storm water.
Since the devastating landslide season of 1996/1997, which involved over 300 reported landslides, the city has taken steps to prepare and respond to slides by constructing mitigation projects to reduce the potential for future slides. It has also been presenting these public landslide awareness meetings for owners of landslide-prone property.
If a landslide damages your property and you have an immediate concern for your safety, leave the premises and call 9-1-1. Seattle property owners with structures that may be affected by or endangered by a landslide should contact a geotechnical professional for structural evaluation.
To view the current conditions of the USGS rainfall threshold for landslides, please visit: http://landslides.usgs.gov/monitoring/seattle/rtd/plot.php.
For more information about Seattle landslides and the City of Seattle free landslide awareness meetings, please visit: www.seattle.gov/dpd/emergency/landslides.
Take Winter By Storm is a regional campaign aimed at helping citizens and businesses get prepared before bad weather strikes. Learn more at: www.takewinterbystorm.org.