Sinkhole risk in Clark County, WA: Not karst, but voids possible
Not karst, but voids possible
No soluble bedrock; some pseudokarst (piping or lava-tube ground).
- On soluble rock
- 0%
- At or near the surface
- 0%
- Buried under cover
- 0%
The next step for one property
Not true karst, but soil piping or lava tubes can still open voids - mention it to an inspector.
Across 629 square miles, under one square mile of Clark County maps onto soluble rock. With about 527,269 residents (839 per square mile), most of the county is built up, so a mapped unit is likely to sit under somebody's street. The figures come from 285 map points about 1.5 miles apart, so a pocket smaller than that can be missed or overstated.
Read next: how ground with no limestone still opens up, and how these percentages are measured.
Counties around Clark County
The nearest county rated sinkhole country is Emery County, UT, about 759 miles southeast. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.
- Multnomah County, OR 16 mi south · 0% at surface
- Cowlitz County, WA 31 mi north · 0% at surface
- Columbia County, OR 31 mi northwest · 0% at surface
- Skamania County, WA 31 mi northeast · 0% at surface
- Washington County, OR 33 mi southwest · 0% at surface
- Hood River County, OR 44 mi southeast · 0% at surface
Against the rest of Washington
Clark County ranks 14 of 39 in Washington for soluble rock at the surface, and sits above 0% of US counties on that measure.
- San Juan County 4%
- Stevens County 3%
- Pend Oreille County 2%
- Okanogan County under 1%
- Ferry County under 1%