The single biggest hazard that people will encounter in Karst environments are sinkholes and cave-ins. When the limestone is dissolved from under the ground, void spaces are created underground. Unfortunately, it is difficult to determine where these void spaces are located. When they grow large enough the rock above them can no longer be supported. When this happens, a sinkhole forms on the surface. The big danger here is when sinkholes form where buildings are located. The buildings will collapse and anyone inside is in serious danger.
Another danger in this type of area is from recreational hiking. Exposed rocks in the area are being continuously chemically weathered. They can shift, crack, and break over time. If people are walking or climbing these rocks, the process can be accelerated.