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File Number: 13-571 eastern edge of the City is crossed by the Hayward Fault, creating the potential for significant damage. The city is also vulnerable to damage from earthquakes on the San Andreas Fault , located 10 miles to the west, and the Calaveras Fault, located 10 miles to the east. All such major faults have numerous fault complexes and branches. Recent significant seismic events include the 1989 Loma Prieta earthquake on the San Andreas Fault , centered about 60 miles south of San Francisco, which registered 6.9 on the Richter scale of earthquake intensity. That earthquake caused fires and collapses of and structural damage to buildings, highways and bridges in the Bay Area . Enforcement of the UBC by the San Leandro Building Division helps ensure that new construction will withstand the forces associated with a major earthquake. However, many of the buildings in San Leandro pre-date the modern UBC and are susceptible to damage. The City has completed a multi-year program to retrofit unreinforced masonry buildings (URMBs), most of which are located in and around downtown. In April 2008, the Working Group on California Earthquake Probabilities (a collaborative effort of the U.S. Geological Survey (USGS), the California Geological Society, and the Southern California Earthquake Center) reported that there is a 63% chance that one or more quakes of magnitude 6.7 or larger will occur in the Bay Area before the year 2038. Such earthquakes may be very destructive. The USGS predicts a magnitude 7 earthquake occurring today on the Hayward Fault, would likely cause hundreds of deaths and approximately $100 billion of damage. Property within the City could sustain extensive damage in a major earthquake, and a major earthquake could adversely affect the area’s economic activity. As noted above, City Hall is comprised of three structures which are combined to function as one building, all constructed on very firm soil. The building was seismically retrofitted, beginning in 1994, and a soils investigation was also conducted at that time, which investigation found the building’s underlying soil to be generally high in clay content or dense in consistency and thus not considered susceptible to liquefaction. In 1994, the soil moved as part of the seismic retrofitting was excavated a minimum of five feet and replaced with engineered fill. Flood. Flood hazards in San Leandro are associated with overbank flooding of creeks and drainage canals, dam failure, tsunamis, and rising sea level. During the last 40 years, urbanization in the watersheds has increased impervious surface area, which has resulted in faster rates of runoff and higher volumes of storm water in the channels. Recent maps published by the Federal Emergency Management Agency (FEMA) indicate that a 100-year storm (e.g., a storm that has a 1% chance of occurring in any given year) could cause shallow flooding in parts of southwest San Leandro. The City’s Floodplain Management Ordinance requires that new construction , additions and major home improvement projects are raised at least one foot above the base flood elevation. The City is also working with the Alameda County Flood Control and Water Conservation City to increase the carrying capacity of flood control channels. Measures being pursued include redesign of the channels, replacing undersized culverts, and keeping the channels well-maintained and free of debris. Page 3 City of San Leandro Printed on 11/12/2013