Glendale (PDF) - Hazard Mitigation Web Portal - State of California

Natural Hazards Mitigation PlanCity of Glendale, CaliforniaSection 6 – Earthquakes• Several electrical transmission towers were damaged or totally collapsed. Collapse wasgenerally due to foundation distress in towers that were located near ridge tops whereamplification of ground motion may have occurred. One collapse was the result of aseismically induced slope failure at the base of the tower.• Damage to above ground water tanks typically occurred where piping and joints wererigidly connected to the tank, due to differential movement between the tank and the piping.Older steel tanks not seismically designed under current standards buckled at the bottom(called “elephant’s foot”), in the shell, and on the roof. Modern steel and concrete tanksgenerally performed well.• The most vulnerable components of pipeline distribution systems were older threaded joints,cast iron valves, cast iron pipes with rigid joints, and older steel pipes weakened bycorrosion. In the case of broken water lines, the loss of fire suppression water forced firedepartments to utilize water from swimming pools and tanker trucks.• Significant damage occurred in water treatment plants due to sloshing in large water basins.• A number of facilities did not have an emergency power supply or did not have enoughpower supply capacity to provide their essential services.• Lifelines within critical structures, such as hospitals and fire stations, may be vulnerable.For instance, rooftop mechanical and electrical equipment is not generally designed forseismic forces. During the Northridge quake, rooftop equipment failed causing malfunctionsin other systems.• A 70-year old crude oil pipeline leaked from a cracked weld, spreading oil for 12 miles downthe Santa Clara River.• A freight train carrying sulfuric acid was derailed causing an 8,000-gallon acid spill and a2,000-gallon diesel spill from the locomotive.The above list is by no means a complete summary of the earthquake damage, but it does highlightsome of the issues pertinent to the Glendale area. All lifeline providers should make an evaluation ofthe seismic vulnerability within their systems a priority. The evaluation should include a plan tofund and schedule the needed seismic mitigation.2006 PAGE 6 - 34