Friday, May 5, 2017

The Van Zandt Slide Gets Some More Attention

Dave Petley calls attention to the use of LiDAR (light detecting and raging) and the Van Zandt landslide in Whatcom County ( His post is in part derived from a bellinghamherald article that covers the recent work of the Washington State Department of Natural Resources Division of Geology and Earth Resources (DNRGER). He also gave my blog a nice compliment - I did a short write up on the Van Zandt Landslide (van-zandt-landslide-introduction) a while back after a trip to the slide with Geoff Malick. Goeff is getting near completion of his thesis on the slide.

The DNRGER has developed and recently expanded their geology information map portal The portal provides geologic maps but has also recently added LiDAR coverage.

I typically do not use the portal very often as I have most of the maps I need and their accompanying pamphlets/booklets. However, a separate portal of really good LiDAR imagery has recently been developed by the DNRGER ( This portal does not include as much LiDAR derived imagery as the main geology portal as a lot of LiDAR areas have yet to be added. But the quality of the imagery is sharper and allows one to pick which LiDAR flight to view when there are multiple LiDAR flights available. It also allows turning on or off the bare earth imagery. The site can also be used to download the raw data.

Below are the two images of the VanZandt Slde deposit from the portal - I should note some resolution gets lost in the process of saving the images to Blogger transferable images.

The DNRDGER has been getting really good at working with the LiDAR derived imagery by assigning color shades to elevations.

The imagery goes a long way to understanding where potential hazards are located. It has been my experience that the imagery is generally well understood by non geologists and the images certainly help me explain slide locations. The resources that the DNRGER are providing our state will go a long way towards better hazard planning - depending on how planners and politicians act.

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