City of Irvine
2020 Local Hazard Mitigation Plan
Figure 3-5: Landslide Hazard Areas
the City of Irvine has taken numerous steps to mitigate landslide hazards as part of the development process. As a result, the City has not experienced significant landslide events. Subsidence According to data from the USGS, there are records of historical and current subsidence in Orange County as a result of excessive groundwater pumping in the first half of the 20th century, as discussed above. Due to better management practices promoted and monitored by OCWD, the overall risk of subsidence has decreased, though areas of isolated subsidence could still occur.
Risk of Future Events
Landslide Given the topography and geologic units within the foothills of the Santa Ana Mountains and San Joaquin Hills, it is anticipated that landslide risk will remain high in those areas. However, the City requires mitigation of these types of conditions, which reduces landslide potential in the developed areas of the City. Regarding seismic activity, as Figure 3-6 illustrates areas of the foothills of the Santa Ana Mountains and San Joaquin Hills that have the potential to fail during an earthquake. Destabilization of slopes and hills due to intense rainstorms also has the potential to cause future landslides. These can be further exacerbated after a wildfire, where vegetation becomes loosened and, therefore, more susceptible to
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