Washington’s widely varying climate and topography along with complex geology creates many areas that are prone to landslides. Identifying past landslides is the best way to identify future landslide hazards.
After the devastating SR530 “Oso” Landslide in March 2014, the state legislature recognized the need for a greater emphasis on landslide mapping. Resources were allocated to the Department of Natural Resources to assemble a group of geologists who specialize in landslides in order to increase understanding and awareness of this destructive natural hazard.
What We Do
The Landslide Hazards Program is part of the Division of Geology and Earth Resources (DGER) within the Washington Department of Natural Resources (DNR). We use a combination of cutting-edge, computer-based mapping as well as fieldwork to identify landslides. We are implementing a mapping protocol first developed and put into practice by the Oregon Department of Geology and Mineral Industries.
DGER geologists on a recent boat survey of the Pierce County shoreline, with the Olympic Mountains in the background.
Pilot Project: Pierce County
For any landslide mapping project, high-quality lidar is a necessity. For the Pierce County Project, this data was fortunately already available. We used the terrain models in conjunction with geographical information systems (GIS) to remotely identify and delineate potential and known landslides. Next, we assigned each of the potential landslides with low, medium, or high confidence values to denote the certainty of their presence on the landscape. We field checked a percentage of the landslides to gather more information about the local geology.
Above: Map of the current landslide inventory (blue) and the Pierce County pilot project study area (orange).
We met with Pierce County officials and asked them to prioritize areas of their county for which they would be interested in obtaining a detailed inventory of landslides. We are currently working on producing a detailed landslide inventory, concentrating on areas that present the highest hazard to people and infrastructure. Once complete, the detailed inventory can be used in landslide susceptibility mapping.
Future susceptibility mapping will allow us to make landslide hazard maps for a municipality or area of interest. These maps will combine our inventory of existing landslides with areas our models show are likely to have landslides in the future.
After we have identified areas that are susceptible to landslides, we will begin vulnerability mapping. This last phase uses additional data, such as the value of structures in susceptible areas, miles of road through at-risk areas, and more.
What’s in it for You
The outcome of all of this mapping is GIS and map products that city and county planners, community leaders, emergency managers, and you can use to make informed decisions about use of landslide-susceptible areas. We are also developing a Homeowners’ Guide to Landslides, which will provide information about how landslides are triggered, warning signs that landslide activity is occurring, and how you can reduce your risk.
DGER geologists. Clockwise from left: Kara Jacobacci, Kate Mickelson, Stephen Slaughter, Trevor Contreras, and Alyssa Biel.
Who We Are
We are five full-time geologists with a background in landslides. Combined, we have over 25 years of landslide geology experience.
Program Coordinator: Stephen Slaughter
A Washington native, I have earned a BS and MS in geology from Western Washington University and Central Washington University, respectively. I started with the DNR in 2004 and have worked in landslide hazards for nearly my entire career. I earned my Engineering Geologists license in 2008 and am the program coordinator for the Landslide Hazards Program.
I moved here from the beautiful Black Hills of South Dakota. I earned my BS in geology with a minor in geospatial technology at South Dakota School of Mines and Technology where I researched the Cook Lake, WY landslide. I continued to work on landslides during my job with the USDA Forest Service before coming to the DNR.
I grew up in Oregon, attended the University of Oregon for my BS and MS, and have 14 years of experience in geophysics, groundwater, geologic hazards, and geologic mapping. I earned my engineering geology license in 2013 and serve the landslide hazards program with my knowledge of glacial landforms and deposits of the Puget Lowland, and slope stability issues in working forests.
I’m an East-Coast native. I have a BS in geology from the University of Massachusetts and a MS in earth and climate science from the University of Maine. I specialized in landslide evaluation in Maine’s glacial stratigraphy. After working as an intern in North Cascades National Park in fall 2015, I decided the Pacific Northwest was an awesome place and moved across the country.
I’m a Colorado native with a BS in geology from the University of Colorado and an MS in geology from Portland State University. My Masters’ thesis focused on using lidar to create landslide inventory and susceptibility maps for a watershed in the Oregon Coast Range. I spent the last six years working on landslide hazards at the Oregon Department of Geology before crossing the border to work for DGER.