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inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #26 of 126: Gary Greenberg (gberg) Wed 27 Apr 11 14:14
    
Your account of strain relief reminds me of what happens at the
chiropractor--a good pop seems to relieve some kind of tension. Now, if
only we could feel the stress building up in the tectonic plates or
whatever.

If it were possible to burrow down to where the action of an
earthquake is, would we see a pile of rubble where the pop happened? Is
it like an explosion deep underground? 
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #27 of 126: Andrew Alden (alden) Wed 27 Apr 11 14:18
    
Before I go on any longer, I should point out a public talk on earthquake
prediction will be given by well-known seismologist Susan Hough tomorrow in
Menlo Park, California at the US Geological Survey. If I understand the
format correctly, she gives an expert lecture at noon and a nontechnical one
in the evening. Both will be streamed live. Details at
<http://online.wr.usgs.gov/calendar/>
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #28 of 126: Andrew Alden (alden) Wed 27 Apr 11 14:47
    
<23><24>: the 1755 Lisbon quake -- This is one of those "prehistoric" events
that we can only study from documents and maybe some ruins. The quake
happened at probably the worst time possible -- not rush hour on Friday. No,
it was on All Saints Day, 1 November, right after church. To the people of
the time, alert for divine signs and in a society based on religiously
ordained order, it was a profound shock that I don't think any American can
fully appreciate today. The rest of intellectual Europe was thrown into
turmoil, and the technocrats of the time were spurred to apply rational
inquiry (the word "science" was unknown then) to the event as a natural
phenomenon. It's worth noting that England had suffered a large earthquake
in 1750, and of course the Mediterranean is rattling all the time.

Anyway, modern research points to the plate boundary between Europe and
Africa, out in the eastern Atlantic, as the source. Wikipedia has a nice
summary at <http://en.wikipedia.org/wiki/1755_Lisbon_earthquake>. The
Azores are at the other end of that boundary, a group of volcanic islands.

Volcanoes are not strong things, just piles of broken rock glued together
with tongues of lava. They erode quickly, and they tend to rot inside and
collapse, and magma intrusions can disrupt them from the inside too.
Seafloor surveys have found big chunks of broken volcano, clearly fallen off
the islands at some point in the deep past. Hawaii is also well known for
that. Obviously the splash from something like that would constitute a huge
tsunami. The scientists who put together that scenario in the 1990s caused
an uproar, naturally, but just as a weak building or a large tree being cut
down gives many signs of its impending collapse, surely a volcano will do
the same thing. At least, these days the volcano monitoring programs so
famously derided by Gov Bobby Jindal rely on such signs when they issue
warnings that have saved many lives. So, like the Yellowstone
"supervolcano," the Azores will give us centuries of warning.
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #29 of 126: Mark McDonough (mcdee) Wed 27 Apr 11 14:59
    
Just as an aside, Jindal is a former Rhodes Scholar, so I can only
assume that his statement was pure grandstanding.
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #30 of 126: Andrew Alden (alden) Wed 27 Apr 11 15:03
    
<25> David, I don't want to mangle physics I may not be properly
understanding, but it's clear in physics as well as intuition that energy
wants to channel itself toward the most efficient configuration. Even a
jagged fault through rock that has never broken before will work its way,
over time and repeated events, toward a smooth plane.

That leads to Gary's question, what do faults look like way down there?
They're not crisp, thin cracks but wide zones of crushed rock. Near the
surface, where rock is most brittle, this layer of fault gouge can be
hundreds of meters thick, like at Tejon Pass on the San Andreas fault:
<http://geology.about.com/od/geology_ca/ig/saf1857/saf1857i5gouge.htm>
Click the next photo for a closeup.

Deeper down, where it's hotter and more chemically active, the gouge is
readily turned to clay minerals. Bodies of serpentine rock are also very
slippery and seem to attract faults. When a drilling project in Parkfield,
California succeeded in crossing the San Andreas fault at depth, the cores
were displayed at a memorable press conference:
<http://geology.about.com/od/seismology/ig/safod/pressconf.htm>
My photos of the fault zone follow that picture.

Deeper still, the friction of an earthquake can actually melt the rock,
leaving a telltale feature called a pseudotachylite. I wrote about them at
<http://geology.about.com/od/rocks/a/aa_fractfrict.htm>
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #31 of 126: Andrew Alden (alden) Wed 27 Apr 11 15:18
    
Heh -- I just got a note from the US Geological Survey about my email
Earthquake Notification Service, which I've had for years. Last month after
the Japan quake, I got an alarming number of messages for the aftershocks,
something like a hundred of them in just a couple days. The USGS said
they've just added "aftershock exclusion" to the system by default. But I'm
going to log in and add them back because I keep ferocious tabs on my email
inbox.

Anyone can sign up for ENS service at <https://sslearthquake.usgs.gov/ens/>
and get email for quakes all over the world.

Another thing I do routinely, as part of my morning warmup, is visit the
USGS page of California and Nevada earthquakes at
<http://earthquake.usgs.gov/earthquakes/recenteqscanv/>. The pattern of
small events is interesting to watch, and of course anything big (M 4.5 and
bigger in the U.S.) I get ENS messages for.
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #32 of 126: We're carrot people. (unkljohn) Wed 27 Apr 11 15:18
    

Thanks for this.  I find it all fascinating.
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #33 of 126: Tom Howard (tom) Wed 27 Apr 11 18:54
    
Thanks for all, and most recently the discussion of Mark's Lisbon
question.

Also, interested in something Mark, I believe, brought up in the
general Japan Fukushima reactor problems discussion:  there was a huge
tsunami that occurred in the same area 1200 yrs ago; if the reactor's
lifespan was calculated to be at least the 40 yrs it's been there; that
ended up giving us a 1/30 chance that the plant would be overwhelmed
by another tsunami.

a. is my math correct
b. is this a legitimate way of looking at the risk? Would you move
next to something that had a 1/30 chance of killing your newborn?
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #34 of 126: Mark McDonough (mcdee) Wed 27 Apr 11 21:00
    
Which actually raises an interesting question for everyone here who
lives in earthquake country - how do you think about the risk day to
day?

I lived in San Francisco for several years in the late 1970s and early
80s after taking a bunch of courses in geology.  One of these courses
included the showing of a very well-made film about San Francisco with
the title "The City That Waits to Die."

Even knowing all this, I moved there and enjoyed living in San
Francisco.
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #35 of 126: David Gans (tnf) Wed 27 Apr 11 21:27
    

As noted earlier, I have lived in California my entire life and I have
experienced hundreds of earthquakes including some big ones.  I have never
sustained one bit of damage - not even books knocked off shelves.
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #36 of 126: Andrew Alden (alden) Wed 27 Apr 11 21:27
    
The risk? I dwell every day on the possibility, not the risk. Maybe that's
just a good way of living with risk without thinking about it, but to my
mind odds are a crapshoot. There is no really sound theory about earthquake
recurrence, only odds. In the case of my fault, the Hayward fault, we know
from trenching studies that there have been about ten large quakes over the
last 2000 years or so; the average interval between the last six is 140
years, and it's been 142-plus years since the last large quake in October
1868. Beyond that is simply unknown, and I strive mightily, as do most
seismologists, against the idea of being "overdue" for the next earthquake.

One of the hardest scientific ideas for humans to grasp, and one of the
latest to enter science and the public domain, is probability and
its relation to randomness and order. When you think that modern science
began with perfect Euclidean geometry, absolute time and space, the
clockwork cosmos of Copernicus and Newton -- that's centuries of bias toward
the Cartesian notion that everything can be rationalized and calculated.
Earthquakes are very close to random, at least in time. We do have pretty
good information on where they occur in space, but anything beyond that --
sizes or dates, for instance -- is simply a blank. We don't have any way of
choosing Door Number 1, 2 or 3 through 100.

But I'd like to know how others of you go about your lives in earthquake
country.
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #37 of 126: David Gans (tnf) Wed 27 Apr 11 21:42
    

We have some earthquake prep in ur house, but not much.  One cupboard in our
kitchen with a latch so we can be annoyed every damn day of our lives rather
than have to pick up shards of coffee mug when that day does come.
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #38 of 126: Dan Flanery (sunspot) Wed 27 Apr 11 21:42
    
>Which actually raises an interesting question for 
>everyone here who lives in earthquake country - how 
>do you think about the risk day to day?

I probably think a little about it every day.  I was nuts about
earthquakes and - to a lesser degree - tsunami when I was a little kid
(also, dinosaurs!).  They scared the shit out of me, but I found them
fascinating.  One of my favorite books was one of those little
Scholastic books on earthquakes I got at a school book sale.  I
remember reading that thing in bed many, many times just before dozing
off.  It was published in the early '70s, when plate tectonics was new,
and had a lot of coverage of the big Alaska quake.

I remember when we visited a great aunt in Chino in '77 or thereabouts
that I was very nervous regarding earthquakes.  It's ironic I'd end up
living in earthquake country.  I guess I confronted my fears.

But I'm also fairly well prepared for a quake.  I have a large
earthquake kit with food and water, a campstove, cookware, rope . . .
even an axe.  And after watching footage of the folks in New Zealand
coping with the aftermath of the Christchurch quake I bought a couple
of hardhats, one for home and one for the office.  There may be lots of
rubble to contend with, and folks who need rescuing.
 
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #39 of 126: Dan Flanery (sunspot) Wed 27 Apr 11 21:43
    
I need to get those latches, though...
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #40 of 126: Mark McDonough (mcdee) Wed 27 Apr 11 22:16
    
There is some truth to the "overdue" concept, isn't there?  

Yes, there's an element of randomness, but quake intervals also
reflect plate movement (building up strain) and the strength and
"stickiness" of the fault boundary.

So sure, if the last n quakes in a particular area have happened on
average every 250 years, that doesn't really mean you're 10 years
overdue at 260 years - but it definitely means you're pretty unlikely
to go 750 years without a quake unless something has changed.
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #41 of 126: paralyzed by a question like that (debunix) Wed 27 Apr 11 22:30
    
Re:  earthquake preparedness--I'm a native Californian, used to the
occasional shake rattle & roll.  I do think about earthquakes when I'm
setting things up & rearranging and redecorating, and do a few simple
things like keeping bookcases slightly tilted towards the wall, and
storing some fragile items in cupboards rather than displayed on open
shelves.  By habit & inclination I always have plenty of food in my
pantry, although not all of it is 'ready to eat'--but a little water
and fuel and I could feed quite a few people for many days with the
bulk grains and beans etc.  I've got matches and candles and
flashlights, but have never developed a proper emergency kit--I just
can't stand the idea of buying gallons and gallons of unneeded water,
boxes of batteries, and cans of food that I don't otherwise have any
need for, to be wastefully disposed of (once outdated and needing
replacement, most places you could otherwise donate such won't accept
it) and replaced at regular intervals, and ditto batteries and other
things that need to be kept fresh.  

Instead, I hope a neighbor with a barbecue keeps enough charcoal &
bottled water that we can make do together with my hotpot & hibachi and
stores of beans and rice.  

If I'm able, I expect I would be spending most of my time at work at
the hospital (I live within walking distance), filling in for some
others who might not be able to get there, depending on the degree of
infrastructure damage.

Or perhaps I'll just get thoroughly squished by one of my unsecured
bookcases, and then it won't matter whether I was otherwise prepared or
not!
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #42 of 126: Mark McDonough (mcdee) Wed 27 Apr 11 22:44
    
While I'm not expecting a 9.0 in Northern Virginia, I'm like you -
I've got a ton of food in the pantry.  My Mormon neighbors saw it once
and said I had way more than them (which is a little worrisome).
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #43 of 126: spinning around like an errant, tuxedoed rinse cycle (thelobster) Wed 27 Apr 11 23:17
    
>a. is my math correct
>b. is this a legitimate way of looking at the risk? Would you move
next to something that had a 1/30 chance of killing your newborn?

I don't want to derail yet another earthquake discussion into a debate
about nuclear energy, but I'll just say that I don't think that your
math is correct.  

For there to be one in thirty odds, you'd have to assume that 100% of
the newborn babies living in the Fukushima exclusion zone were killed. 
As far as I know the actual percentage is rather close to zero, rather
than 100%.  
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #44 of 126: Ed Ward (captward) Thu 28 Apr 11 02:49
    
Thinking of Lisbon makes me wonder about the Western Mediterranean,
where I am (Montpellier). I don't think I've ever heard of an
earthquake around here, even historically, and when a guy I met told me
the city was built on an extinct volcano, I did some googling and
discovered that there is an ancient chain of dead volcanoes rising out
of the sea at Agde, about 50 miles west on the coast, but nothing
around here. Hell, we're all limestone, so we *couldn't* be volcanic,
right? 

Makes me wonder, though: are there any 100% non-quake zones anywhere
on the planet?
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #45 of 126: Tom Howard (tom) Thu 28 Apr 11 07:15
    
<thelobster>, thanks for mentioning my question.  There are so many
things wrong with what I was posing, I scarcely got around to posting. 


I was hoping <mcdee> might've mentioned, if it had been him elsewhere,
what he was talking about with the 1200 yr recurrence.

Anyway, I'm thinking it wasn't so much my math as my postulation.  Not
that your newborn baby would die, but that the people would allow a
plant like that in that area.  Ever.  

And, so, to bring it to the earthquake, why would you subject someone
you are responsible for to that risk.  The quake will happen, the
tsunami will happen, and a 30km exclusion zone will happen.  Would you
bring your baby to that area?

Personally, I am somewhat like <debunix>.  Yes, all those things might
happen, but I'm not responsible for any children ("children" is just
an egregious example), and I'd make do.  Living here inside the DC
beltway, moved here while the Cold War was going on (remember *that*
Ground Zero?), thru our current dirty bomb scenarios, and I'm figuring
no matter how bad it might get, I would be better off than others and
my job would be to assist.
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #46 of 126: Mark McDonough (mcdee) Thu 28 Apr 11 07:41
    
I have some older relatives who live in a fire-prone area.  Their
house is completely surrounded by thick brush.  It's a beautiful area,
and it's a beautiful setting for their house.  I asked them once if
they were worried about fire.  They just said they'd get the hell out,
let the house burn, and buy an RV.

Human decisions about risk are odd.  If they were more rational, why
would anyone live in, say, Los Angeles, which is subject to fire,
flood, and earthquake?  Or for that matter in DC, a prime terrorist
target.  Or build houses on the Atlantic ocean front?
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #47 of 126: paralyzed by a question like that (debunix) Thu 28 Apr 11 07:56
    
Or any place prone to tornadoes, which covers nearly everyplace that
isn't at risk for wildfires, floods, earthquakes, hurricanes, or
volcanoes....

I remember being just a little upset one day, shortly before my
departure from California to St Louis, by a map of tornado activity
that clearly included St Louis as one of the higher-risk parts of the
midwest.  In the time I was there, there were of course tornadoes
around the area, but the city itself mostly was spared (although this
year one hit the airport rather impressively).  

But I could rationalize the net risk as lower than earthquake country
because tornadoes are so localized in their most severe effects.   The
risk one is going to get *you* is pretty low even in tornado alley.  
The risk you're going to be affected by a big earthquake nearby is
bigger, because their impact is more broadly devastating, but it's more
localized in time than in place, so it all balances out.  Or something
like that was how I rationalized it to myself when I moved back to
California.

 
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #48 of 126: Ted Newcomb (tcn) Thu 28 Apr 11 08:44
    
http://www.grist.org/article/2011-01-19-california-superstorms-could-make-quak
es-look-tame-and-brisbane-

What do you think about these superstorms NOAA is predicting, as well
as the solar storms I keep reading about that might electromagnetically
wipe out  our satellite communication network??? Is this sci-fi run
wild or potentially true in our near-future?

Are these earthquakes part of some synergistic weather planetary
cyclical pattern???
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #49 of 126: Peter Meuleners (pjm) Thu 28 Apr 11 08:45
    
I've lived in the greater East Bay my entire life, felt dozens of
quakes, including Loma Prieta, and never think about them unless they
come up in conversation or one happens.  They're just a part of life. 
If they do no damage I actually enjoy them.  They connect me to the
planet I walk on in a very direct manner.
  
inkwell.vue.406 : Andrew Alden on Earthquakes
permalink #50 of 126: Andrew Alden (alden) Thu 28 Apr 11 10:02
    
Now that's a real California attitude!

Philip Fradkin has argued, and I think I agree, that earthquakes have always
shaped the Californian character. The very first expedition to California,
in 1769, walked right into a large Southern California earthquake. We've
always had this charming ability to roll with the punches. Seeking stability
in a roiling world is a Zen kinda thing -- and hey, Zen is from Japan.
  

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