In the central valley, some areas have sunk 30+ft over the past century due to aquifers collapsing. http://www.watercalifornia.org/projects/projects_img/enid/f

In the central valley, some areas have sunk 30+ft over the past century due to aquifers collapsing. http://www.watercalifornia.org/projects/projects_img/enid/fables_large.jpg http://www.watercalifornia.org/projects/projects_img/enid/fa... http://www.capradio.org/articles/2013/11/22/usgs-study-1200-square-miles-of-central-valley-land-is-sinking/ http://www.capradio.org/articles/2013/11/22/usgs-study-1200-...