Going a bit deeper, the earthquake took out most of the water supply to the fire hydrants in the city, and so the fire department couldn't put out the fires that started during the quake.
As a result, SF now has a backup hydrant system! Those big fat multi-colored hydrants are all connected to a fire-only water system that's gravity-fed from cisterns all over the city. The colors of the hydrants encode information about which cistern the water comes from, IIRC. And whenever you see a random arc of a circle made of brick inlaid in the road, that's outlining the location of a cistern.
I don't have the link handy, but I was reading an article about how the backup water system is inadequate for the western part of the city (Sunset district mostly) and they're figuring out now how they want to extend it.
I recall reading an article from a year or two ago stating that a lot of those cisterns are empty, and the overall backup water supply is woefully insufficient.
San Francisco has 66 fire trucks the last time I checked (I’m an SFFD volunteer). If there is a bad enough earthquake they will not come for you. The sheer volume of fires and service response calls will overwhelm them. It is your responsibility and the responsibility of volunteers in your community to make sure everyone is safe or triaged correctly the first 2 days (7 days better) after a disaster.
Neighborhoods will definitely burn but containment will be more of a factor of how windy it is and how easy it is to get to water.
> If there is a bad enough earthquake [the fire department] will not come for you. The sheer volume of fires and service response calls will overwhelm them.
Wish your comment was higher up.
If you're in the Bay Area: sign up for a NERT/CERT class, buy an ABC fire extinguisher, and know where and how to shut off your gas line. Assume the fire department will not get to you.
Many 1906 SF fires were intentionally set by the owners themselves, after the earthquake had damaged their buildings, because most insurance policies covered losses due to fire, but not those due to earthquake. So, if you burned your building down completely, leaving no evidence that it had been first damaged by the earthquake, you had a chance at being reimbursed. http://www.sfmuseum.org/1906.2/arson.html
It's not clear how much of the fire damage was due to intentionally set fires; there were also a significant number of fires started unintentionally when the fire department dynamited various buildings in failed attempts to establish fire breaks. (And, hey, you were still covered if your building was dynamited!) So, lets hope the SFFD is better in this regard than in 1906 as well.
It's not just the fire department that's better - in 1906 a lot of those fires were caused when the quake would pull a gas appliance from a wall and leave a gas leak that later ignited.
Nowadays everyone has their hot water heater and oven bolted or strapped to the wall. I'm sure there are other useful fire codes California has adopted since then but this one rule will probably prevent more fires in the next big quake than any other.
My LA house has to have a shutoff that automatically kills the main gas line during an earthquake. One must be installed when the house changes hands. No grandfather clause exception allowed.
yes, i'd forgotten about those; we got one installed at our house a couple years ago, iirc at no charge from PG&E. it's definitely better/safer than the per-appliance solutions.
What caused the most damages was the fires after the earthquake.
Hopefully SF has a better fire department now than in 1906.