The California Seismic Safety Commission has funded the PEER Center to conduct research related to fire following earthquakes. Prof. Charles Scawthorn, a Visiting Scholar at the PEER Center , is leading the study entitled Water Supply in Regard to Fire Following Earthquake. This work is supported from the Commission’s Research Program and is expected to be six months in duration.
The purpose of the study is to review the current status of emergency water supply in California vis-a-vis needs for fires following earthquake and provide a series of recommendations for improvements if and where needed. Issues to be discussed include fire ignitions following earthquakes, the status of the state’s urban water systems, the status of urban fire departments’ emergency water supply, and opportunities to enhance emergency water supply systems.
Fire following earthquake (FFE) is a significant problem in California. Historically, every significant earthquake in California has resulted in multiple simultaneous fires that have strained, and at least in 1906, overwhelmed the fire service. In both the 1971 San Fernando and the 1994 Northridge earthquake, there were over 100 ignitions. Other disasters clearly demonstrate that massive fires are a problem in California under even non-earthquake ignitions, when onlyone or a few ignitions are involved – the numerous wildland urban interface fires that occur in California almost every year are only the most telling example of this – another example is the 1988 First Interstate Bank Fire, which totally destroyed 4 floors of the state’ s tallest building (at that time) and severely damaged the rest of the building through water and smoke damage.
In the absence of a major recent earthquake affecting the urban centers of California, the 2008 ShakeOut2 and associated Golden Guardian Exercise examined potential fires assuming a Mw 7.8 event on a morning in mid-November, with breezy, low humidity conditions. The analysis found that approximately 1,600 ignitions occur in Southern California, with the central Los Angeles basin experiencing hundreds of large fires. The estimated loss was estimated to be hundreds to perhaps a thousand lives, and approximately 200 million sq. ft. of residential and commercial building floor area, worth perhaps as much as one hundred billion dollars and virtually all insured.
While the fire service in California since 1906 has professionalized and advanced technologically to the point of being perhaps the best in the world, it has not been tested by a major earthquake since 1906. And, the Achilles Heel in 1906 was not the fire service itself, but rather the failure of the water supply – without water, firefighters may be able to save some lives but are handicapped to the point of helplessness for putting out fires. Water systems in California have failed in virtually all urban earthquakes in California – not only 1906, but also in the San Fernando, Northridge and the 1989 Loma Prieta events. As a result of these more modern events, water departments have engaged in major reviews of their system’s seismic vulnerability, and spend hundreds of millions of dollars retrofitting their systems. Exemplary programs include LADWP and MWD in Southern California, and EMBUD and San Francisco’s Hetch Hetchy system in Northern California, to name a few of the larger programs.
Nevertheless, the Achilles Heel of these systems, and the entire fire following earthquake problem, remains the distribution system – despite massive seismic retrofit programs, it has not been possible to replace all of the distribution systems, and it is quite possible that numerous distribution breaks will occur in the high intensity areas of a major earthquake, which will also be the areas most likely to have many fires. These breaks will not cause system-wide loss of water, but will cause loss of water in the neighborhood of the fire – for the firefighter, effectively the same thing. Knowing this, fire departments have identified and developed plans to access alternative water sources – in most cities for example, these include swimming pools, tanks, creeks, ponds and storm water drains. San Francisco, due to its experience in 1906, has gone far beyond this, to develop and maintain the high pressure seawater supplied Auxiliary Water Supply System (AWSS) and over 170 cisterns (underground water tanks spread throughout the city) In fact, San Francisco has a $412 million bond issue on the June 2010 ballot to enhance this system. However, other cities, particularly Los Angeles, San Jose and San Diego, lack such systems and, quite worryingly, the capacity of their water supplies (normal, and alternative) have never been examined vis-a-vis the demands that multiple simultaneous post-earthquake fires will place on those supplies.
 Scawthorn is a California Structural Engineer and in 2008 retired as Professor of Earthquake Engineering, Kyoto University (Japan). He is an editor of the ASCE Monograph Fire Following Earthquake and well known for his work on this topic.