http://www.ngs.noaa.gov/GRD/GPS/Projects/CB/SUBSIDENCE/subsidence.gif

http://www.msstate.edu/dept/geosciences/CT/TIG/WEBSITES/LOCAL/Summer2003/Buffington_Deborah/sinkhole.jpg

Subsidence

• sinking of ground surface(vertical deformation)

• Rates can vary (collapse to gradual)

• Caused by removal of subsurface fluids (oil, ground water, steam, gas) or solids (limestone dissolution, coal, salt)

Karst

Typical karst topography developed on carbonate bedrock in Russell County, VA Valley & Ridge province. From Lebanon 7.5' topographic map. http://www.wm.edu/geology/virginia/karst_topography.html

http://www.env.duke.edu/eos/geo41/gw2.htm

http://capp.water.usgs.gov/gwa/ch_b/gif/b094.gif

Ground water “mining”

http://ga.water.usgs.gov/edu/graphics/mapsubsidence.gif

http://www.extension.umn.edu/distribution/cropsystems/components/3115s01.html

http://capp.water.usgs.gov/gwa/ch_e/E-coastal_low5.html

subsidence from mining subsurface coal

http://www.ohiodnr.com/geosurvey/geo_fact/geo_f12.htm

http://ga.water.usgs.gov/edu/earthgwlandsubside.html

http://www.ohiodnr.com/geosurvey/geo_fact/geo_f12.htm

http://www.youtube.com/watch?v=dHol4ICeDoo

Lake Peigneur, LA – salt mine collapse History Channel footage

http://www.oca-arb.co.uk/img/trs_clip_image002.jpg

http://geochange.er.usgs.gov/sw/changes/anthropogenic/subside/

recognizing subsidence at your site