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69 <br /> <br />5.3.1 HISTORIC BAY AREA EARTHQUAKE OCCURANCES <br /> <br />The Bay Area has experienced significant, well-documented earthquakes. In 1868, a <br />significant earthquake occurred on the Hayward fault with an estimated magnitude <br />of 6.8-7.0. The fault ruptured the surface of the earth for more than 20 miles and <br />significant damage was experienced in Hayward and throughout Alameda County, <br />and as far away as San Francisco, Santa Rosa, and Santa Cruz. The M7.8 1906 <br />earthquake on the San Andreas Fault, centered just off the coast of San Francisco, <br />devastated San Francisco and caused extensive damage in Oakland, San Jose, and <br />Santa Rosa. More recently, the M6.9 1989 Loma Prieta earthquake caused severe <br />damage in Santa Cruz and the surrounding mountains, where it was centered, as well <br />as fatal damage 50 miles away in Oakland and San Francisco. Moderate earthquakes <br />are much more common in the Bay Area; twenty-two have occurred in the last 178 <br />years, averaging every eight years.3 The 2014 South Napa earthquake is a reminder <br />of the strong shaking that even a moderate magnitude 6.0 earthquake can produce in <br />a localized area. Because the 1906 earthquake released so much energy and stress <br />on regional faults when it ruptured, the last 100 years have been relatively seismically <br />quiet. As faults restore their stress and energy builds again, the region may have a <br />more seismically active future. <br /> <br />There have been six earthquake-related declared disasters in the Bay Area since <br />1950. Only the 1989 Loma Prieta Earthquake directly affected San Leandro. San <br />Leandro had no reported deaths or injuries due to the Loma Prieta earthquake, and <br />no major damage. Most of the reported damage was personal belongings, and minor <br />to moderate structural damage to dwellings. San Leandro’s Emergency Operations <br />Center was open to observe and assist as needed. <br /> <br />5.3.2 EARTHQUAKE HAZARDS <br /> <br />Earthquakes can trigger multiple types of seismic hazards, causing varying severity <br />of damage in different locations. The following sections describe each earthquake <br />hazard in greater detail, including where and how it is likely to affect the Bay Area <br />and more specifically, San Leandro. <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />108