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82 5.3.7 Landslide In the Bay Area landslides typically occur as a result of either earthquakes (earthquake- induced landslides), or during heavy and sustained rainfall events. A given area can be at risk for both earthquake-induced landslides as well as landslides caused by rain-saturated soils but the variables that contribute to each landslide risk are different. Typically, an earthquake-induced landslide occurs when seismic energy at the top of a slope gets concentrated and breaks off shallow portions of rock. In rainfall-induced landslides, the slide can begin much deeper in the slope, in very-saturated layers of soil. For both types of landslides, there are not currently methods available to estimate the probabilities of future landslides at a local, or jurisdictional, scale. Steep slopes and varied types of underlying soils can influence the likelihood of landslides. Additionally, surface and subsurface drainage patterns also affect landslide hazard, and vegetation removal can increase landslide likelihood. Future landslides are most likely to occur within and around the places where they have previously occurred.5 PAST OCCURANCE AND POTENTIAL FOR OCCURANCE: San Leandro has not experienced any landslides from past earthquakes. The eastern hills are generally stable and not susceptible to sliding due to earthquake, but the Bay O’ Vista region of San Leandro, pictured in Figure 5-12, has been effected by rain related slides in the past. In 1997/1998 during an Atmospheric River period of rain two homes located on Hillside Drive were pushed from their foundation due to moving soil from the hillside. There were no injuries or death from the incident, but both homes had major damage and had to be demolished. 5 USGS (1999) 121