AH Challenge: Effects of a bigger Sylmar quake

As you may remember, this past February marked the 40th anniversary of the 1971 Sylmar earthquake that ravaged much of Los Angeles. As bad as it was, it could easily have been worse...and your mission, should you decide to accept it, is to craft a scenario describing how much worse and what the consequences of a more powerful Sylmar quake would have been for LA and for America as a whole.
 
Making this or any quake more powerful would require something along the lines of having a nuclear missle strike along the fault line simultaniously w/the quake. While increasing the damage of an earthquake is quite doable, making an earthquake more powerful ("bigger") is pretty ASBish.
 
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The quake itself doesn't need to be stronger for there to be a much worse result. Just have the quake trigger a major fire that gets established before LAFD can knock it back. The PoD would be a human decision to locate a natural gas line somewhere else, build a 'quakeproof' fire command center that gets disabled by the quake (happened IOTL - Northridge quake, IIRC), etc.

Start a good sized fire and knock out LAFD's comms for thirty minutes and you could burn a good portion of the city to the ground.

The long-term outcome would probably be positive: better building and fire codes designed to prevent "The Great LA Fire" from ever happening again would save a lot of lives in later quakes.
 
Lord Grattan: You have a point...I probably should have said "effects of a more damaging Sylmar quake".

Gridley: The fire could also be triggered by having the quake knock down a utility pole and the pole(or one of the cables attached to it) hit a gas or chemical tank. A spark or two in the right place and...BOOM!
 
You should see this for some ideas.
http://www.archive.org/details/Earthqua1973
I was first informed about this from a friend and mentor who's dying of cancer and appeared in it in a minor role as a CAP member.

Perhaps key people are injured or killed in the quake?
Perhaps the VA hospital collapses totally?
Perhaps the response touches ethnic or racial nerves and riots result?
 
I don't know that in geologic terms it would be hard to make the quake stronger. Just eliminate some prior event that removed some of the strain and have a slightly stronger bind on the strain to let it last until 71
 
Making this or any quake more powerful would require something along the lines of having a nuclear missle strike along the fault line simultaniously w/the quake. While increasing the damage of an earthquake is quite doable, making an earthquake more powerful ("bigger") is pretty ASBish.

Lord Grattan: You have a point...I probably should have said "effects of a more damaging Sylmar quake".

Gridley: The fire could also be triggered by having the quake knock down a utility pole and the pole(or one of the cables attached to it) hit a gas or chemical tank. A spark or two in the right place and...BOOM!

I don't know that in geologic terms it would be hard to make the quake stronger. Just eliminate some prior event that removed some of the strain and have a slightly stronger bind on the strain to let it last until 71

I disagree with Lord Grattan. Earthquakes are chaotic events. Chaos, in physics, has been adopted as the term for "stuff that is actually deterministic but looks random to us because there are lots of positive feedbacks that make small variables potentially very significant and/or lots of variables hidden from our observation, not by fundamental quantum physics but by our practical limits."

So I'm not saying the 1971 Sylmar quake could have been any random magnitude one cares to name. There would, in the underlying geophysics of any particular timeline, be an upper bound set be the degree of unrelieved stress that had built up in the crust on that fault.

But I believe that the actual energy released in any particular quake is always a fraction of that total potential--sometimes a large one approaching 1, sometimes much smaller. Someone who knows more than me about the current state of geological science might be able to state what percentage of the possible tectonic energy available was actually released in 1971; if it was a lot less than 100 percent I don't think it would require any major divergence for it to have been a much larger amount in an alternate timeline. If that route is available then a logical consequence would be that in that timeline for some time after the possible magnitude of later earthquakes in that region would be limited.

Or it seems perfectly reasonable to me to go with an alternate timeline where the geological POD was much longer ago, and the potential stored up was greater, and yet have it run as close as one likes to OTL up until the effective historical POD of the larger quake that releases the greater energy (and conceivably leaves as much as OTL, or more, still in reserve for future quakes adding up to the same cumulative magnitude as OTL in the last 40 years).

Strict "butterfly" theory argues that since meterological, biological and human events are examples of the sort of basis for "chaos" I defined above, with lots of positive feedback and hidden variables, therefore even a deep subterranean POD must result in a different world by 1971; I say not necessarily. Because if changing the flow of some mantle material 200 or 2000 or two million years ago in a world otherwise perfectly identical to ours up to that point must mean a different human and indeed geographical world by 1971, there are other timelines that would not have evolved just as ours did without those geological changes, but with them they now converge as closely as we like with our world as of February 1971. This is the other shoe of infinite possible timelines dropping; insofar as "butterflying" events are truly chaotic and not a systematic result of a systematic influence, we can always choose the timelines where simply by chance purely chance events happened to break the way they did OTL, up to our dramatically chosen point of humanly significant divergence.

So, for purposes of alt-historical speculation I see no reason to censor the possible magnitude of an alternate earthquake on a known faultline that actually produces OTL quakes, beyond setting upper limits given by the basic geophysics of the situation--that is, there is some Maximum Big One possible at any time on any faultline, and you can't have one bigger than that. Unless you can squirrel away more stress in an alternate past, but I suppose the more you have stored up the more improbable it becomes that a given time interval would go by without some significant relief of the stress, and providing for a more active subcrustal circulation might run into physical limits and in any event such a systematic change would have systematic consequences, making for a different surface geography and hence a different history.

So there are limits, but if the Sylmar quake released say only 1/10 of the energy it potentially could have, then it could well have been 8 or 9 times as powerful without any need for any significantly observable prior divergence whatsoever, and we can surely shop around for alternate timelines with somewhat more stored up than OTL that nevertheless look indistinguishable from OTL on the surface up to that date.

So while saying "what if due to contingent events on the surface, the response to the Sylmar quake was such that more damage to people and structures accumulated" is itself an interesting challenge, we can just as well imagine WI Sylmar were the Big One, up to the limits geology sets on how big a Southern California quake can possibly be. We aren't compelled to imagine it must be part of the Confederate States or the chief overseas colony of a Basque superpower or that there are no intelligent hominids whatsoever just because of butterflies!
 
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