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Ramsey County Multi-Hazard Mitigation Plan, 2018 Page | 95 is a result of multi-year impacts such as repetitive flooding, wave action, sea level rise, sediment loss, subsidence, and climate change. Death and injury are not typically associated with erosion; however, major incidents of erosion, such as landslides, can destroy buildings and infrastructure (FEMA, 2013). The movement of a mass of rock, debris, or earth down a slope by the force of gravity is considered a landslide. They occur when the slope or soil stability changes from stable to unstable, which may be caused by earthquakes, storms, volcanic eruptions, erosion, fire, or additional human-induced activities. Slopes greater than 10 degrees are more likely to slide, as are slopes where the height from the top of the slope to its toe is greater than 40 feet. Slopes are also more likely to fail if vegetative cover is low and/or soil water content is high. Potential impacts include environmental disturbance, property and infrastructure damage, and injuries or fatalities (FEMA, 2013). The river bluffs around the Twin Cities have a high risk of natural landslides in the spring, when ice thaws within the bluff and destabilizes rock (Stanley, 2018). Soil Erosion/Landslides History in Ramsey County On April 28, 2018, an estimated 400,000 pounds of rock and soil came loose on the bluff to cover Wabasha Street between Plato Boulevard and Cesar Chavez Street. After having an engineering firm study the slope, city officials decided to build a 12-foot-high retaining wall that will run about 250 feet along Wabasha Street. Ramsey County will receive $766,770 from the state’s disaster-assistance fund to help with these repair costs (Stanley, 2018). On May 22nd, 2013, two children were killed in a landslide in Lilydale Regional Park along the Mississippi River. The incident was preceded by several weeks of heavy rain, which inundated the soils around the area (Figure 22). The children were part of a school group looking for fossils. A group of four children were walking on a path on the edge of a bluff when the path collapsed beneath them. Two students died and another two were injured. Two firefighters were also injured (Gottfried, 2013). In 2011, a 20-foot boulder crashed through Bread, Coffee & Cake, a bakery in St. Paul located beneath a bluff near the Wabasha caves, south of downtown. When the owner arrived to bake on an April morning at 2:30 a.m., the place was demolished and gas fumes lingered. The city condemned the building (Jenkins, 2011). Soil Erosion/Landslides and Climate Change The increased magnitude and frequency of flooding events and storm activity that may result from climate change may in turn increase the risk of soil erosion and landslides. According to University of Washington geologist Dave Montgomery, “If the climate changes in a way that we get a lot more rainfall you would expect to see a lot more landslides” (Phillips, 2014). In Minnesota, the wettest days are getting wetter. This can contribute to increased erosion in many locations due to flooding and saturation of soils. Reduced ice cover on lakes and shorelines (due to Figure 22. Landslide in Lilydale in 2013