Landslides
Landslides include any downslope fall or slide of rocks or soils. Heavy rains or the removal of plant cover can trigger landslides. Hennepin County is vulnerable to rock falls, along the Mississippi River gorge from Minneapolis south to Fort Snelling.
Risks of landslides in Hennepin County are low. The steep north wall of the Minnesota River Valley in Eden Prairie and Bloomington has the highest risk in Hennepin County.
The Twin Cities has experienced an increase in landslide activity over the past decade.
Interactive landslide map
Report a landslide
Sinkholes
Sinkholes form when acidic water moves downward from the surface. Or in land underlaid by carbonate rock that is dissolving as ground water moves through it. Cavities develop in the rock and expand through this process. When the cavity is close to the surface, a collapse may occur.
Contamination of groundwater may also happen from sinkholes. The toxic compounds on the surface reach bedrock through the same water routes.
Areas where depth to bedrock is 50 feet or less are at the highest risk. There are some sinkhole conditions in Hennepin County. They exist in a band from near Crystal southward to the area of the International Airport. The risk of sinkholes developing in Hennepin County is low. There are more active sinkhole areas in southeastern Minnesota.
Earthquake
An earthquake is the sudden release of energy from the Earth’s crust. That release results in seismic waves that can be destructive. Most earthquakes happen in active regions of the Earth where huge plates contact each other.
Hennepin County has a much lower risk of earthquakes than most of the rest of the United States. We are far from any active region and are in a stable area.
Yet, earthquakes have struck Minnesota and could do so in the future. The closest earthquake epicenters in Hennepin County were in 1981 in Cottage Grove (3.6 Richter scale) and in 1860 in New Prague (estimated 4.7 Richter scale).