<strong>Safe</strong> <strong>Enough</strong> <strong>to</strong> <strong>Stay</strong>Figure 3: How Will the Expected <strong>Earthquake</strong> Impact San Francisco?Different neighborhoods have different housing s<strong>to</strong>ck <strong>and</strong> soil conditions, which means the degree of earthquakedamage will vary across the city. After a Magnitude 7.2 earthquake on the San Andreas Fault, we expect thepercentages of housing in red <strong>to</strong> be unusable, meaning not safe enough for residents <strong>to</strong> shelter in place.50%MarinaRichmond35%65%Sunset23%77%Merced24%76%50% North Beach27%26%73%Pacific Heights 74%Down<strong>to</strong>wnWestern Addition 27%27%73%73%Central Waterfront28%Mission25%72%75%Twin Peaks17%Bayview16%83%84%ExcelsiorIngleside12%11%88%89%Sources: SFGIS, Census 2000 <strong>and</strong> SPUR analysis of CAPSS Hazus Output Data 27Unusable Units25%1 mile75%Usable Units14 SPUR Report > January 2012
Figure 4: How Much of San Francisco’s Housing Will Be Unusable?In neighborhoods with a high number of vulnerable housing types, such as wood-frame soft-s<strong>to</strong>rybuildings <strong>and</strong> non-ductile concrete buildings, there will be a greater number of unusable housing unitsafter the expected earthquake.NeighborhoodTotal numberof unitsNumber ofunusable unitsPercent of unusable units by structure typeOne- <strong>and</strong>two-familywoodframesoft-s<strong>to</strong>ryWoodframesoft-s<strong>to</strong>ry withthree or moreunitsConcrete builtbefore 1980OtherBayview 9,000 1,500 42% 55% 1% 2%Central Waterfront 9,400 2,700 15% 48% 22% 14%Down<strong>to</strong>wn 54,000 15,000 2% 53% 28% 16%Excelsior 24,000 2,900 58% 38% 0% 4%Ingleside 7,900 900 76% 15% 0% 8%Marina 7,600 3,800 15% 79% 3% 3%Merced 8,200 2,000 16% 33% 28% 22%Mission 48,000 12,000 23% 71% 3% 3%North Beach 26,000 7,200 5% 85% 6% 4%Pacific Heights 19,000 4,800 12% 80% 5% 3%Richmond 27,000 9,400 27% 71% 1% 1%Sunset 38,000 8,600 51% 44% 1% 4%Twin Peaks 17,000 2,900 40% 56% 1% 3%Western Addition 41,000 11,000 12% 81% 4% 3%Total 330,000 85,000 22% 67% 6% 5%Sources: SFGIS, Census 2000 <strong>and</strong> SPUR analysis of CAPSS Hazus Output Data 27structure type. 26 However, this analysis only considers part ofthe picture: whether housing will be safe <strong>to</strong> occupy consideringearthquake damage <strong>to</strong> structures. It does not consider other damageor cascading consequences, such as damage <strong>to</strong> utilities or structuraldamage from fires following the earthquake. The fac<strong>to</strong>rs thatcontribute <strong>to</strong> whether residents choose <strong>to</strong> stay or leave after a disasterare complex, <strong>and</strong> the structural safety of residences is only one pieceof information, albeit an important one. This should be kept in mindwhile reviewing the following figures, which only represent that onepiece.The analysis makes clear that housing in every San Francisconeighborhood would be damaged heavily by a magnitude 7.226 Defining building performance in terms of shelter in place is a new concept.The CAPSS project used the best information <strong>and</strong> methods available at the time<strong>to</strong> estimate the amount of housing that would be usable after an earthquake.This task force has developed improved methods <strong>to</strong> identify which residencescould be used <strong>to</strong> shelter in place, but this new approach has not yet beenapplied <strong>to</strong> San Francisco’s building s<strong>to</strong>ck. The analysis presented in this reportis based on the CAPSS analysis. We are hopeful that an improved analysis willbe conducted some time in the future using the methods developed by this taskforce, producing updated <strong>and</strong> refined estimates of housing damage.27 Hazus is FEMA’s methodology for estimating damage <strong>and</strong> losses for naturaldisasters.SPUR Report > January 2012 15
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