atquake

Eathquake musings

What Have We Learned 10 Years After Sumatra?

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Well, quite a bit, but not enough is the short answer.  In 2004 we were still laboring under antiquated seismological theories about which subduction zones could and could not produce M9 earthquakes.  These theories came from near the dawn of plate tectonics, and had not really been put to the test.  Unfortunately, the Sumatra earthquake and later the Tohoku earthquake put an end to the idea that we can actually make such determinations.  We can’t.  It’s hard for our community to admit this, and many don’t, but I think we have to take a deep breath and accept it, then move on.  Will there be a replacement model?  I don’t know, but am doubtful that a single model will be able to describe the earthquake behavior of the worlds subduction zones.  My gut feeling is that the regional and local geologic context, when added to the commonalities shared by subduction zones, will keep them unpredictable.  So perhaps the lesson here is not what we hope it to be, but it’s there just the same.  We are hoping for some technical discovery, some new machine or new method that will “solve” the earthquake.tsunami problem decisively.  But I think the problem that needs solving is really the way we deal with it.  To make earthquakes and tsunami manageable, we need education above all else.  From education comes preparedness.  From a place of preparedness, we find that prediction is really not that important after all.  If we could predict, but were unprepared, how much good would it do?  In a few cases, warning helps.  Shutting down trains, switching on backup power in emergency rooms, diverting air traffic and that sort of thing, but this comes from short term warning systems which I think have some value.  But the value of preparedness is that it doesn’t depend on any new and untested model, nor on any device that may fail in the heat of the moment.  Chris Scholz new book Stick-Slip talks a lot about what would happen if we actually had an idea about prediction. The likely reality is more complicated that we might think.

In Japan recently on a project with OPB, we saw again the devastation from 2011.  That earthquake/tsunami was in so many ways a success story by comparison to Sumatra.  But it’s hard to look around at the towns that are gone, the piles of debris, and meet the people who lost loved ones, children, parents and friends and think this was a success.

So what have we learned, what can we learn?  I think we owe it to those who live in the path of great earthquake and tsunami to try, even if success looks like Tohoku.  The great test pilots like Bob Hoover, Neil Armstrong and Chuck Yeager say that every street at Edwards Air Force Base is named after one of their friends.  Airline safety that we take for granted is because of learning from all the errors that have been made along the way.  With what is at stake for the millions that live along subduction zones, can we do less?   There was an article today about a new marine science center OSU wants to build in the tsunami zone in Newport Oregon.  Vicki McConnell, the State Geologist thinks that really doesn’t make sense and I agree.

http://www.oregonlive.com/pacific-northwest-news/index.ssf/2014/12/state_geologist_warns_against.html

Only a few years after the Tohoku tsunami, can we not even learn that simple lesson?   I suppose none of the OSU administrators have been to NE Japan lately.  If they had, they might have met Mayor Sato of Minami-Sanriku.  He was the fellow who famously hung onto the cell antenna on top of the three story public safely building as it went under water (below), drowning most of the 58 member staff.  An inspiring man, he feels the weight of responsibility for his town, and the failure of it’s level of preparation.  He’s not your ordinary politician, he has his priorities straight.  https://d13uygpm1enfng.cloudfront.net/article-imgs/en/2011/05/24/AJ201105242660/AJ201107022664.jpg

At the very least, learning from Sumatra (and Tohoku) is simple: don’t build high occupancy buildings in a tsunami zone, particularly when they’re on fill and have limited evacuation options.  The people who work there won’t fully understand the risks they are assuming, the engineering will be based on a lot of assumptions, untested, and likely watered down by politics.   Mayor Sato knows.

Written by eqgold

December 26, 2014 at 8:19 pm

Posted in Uncategorized

Great news!

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Written by eqgold

December 12, 2014 at 6:25 am

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Weirdest geology lectures ever: Part 1

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The recent trailer for the movie “San Andreas” reminded me of a funny story and one of the two oddest geology talks I’ve ever given…  I was headed to Camarillo  CA to MMS to look at some seismic profiles, and a few days before leaving I found an obscure ad in a local flying publication offering dual instruction in a Hawker Gnat Mk. T.1.  I’m a pilot, and like to try new things, but had to look up what a Hawker Gnat was exactly…. When I found out, I called the guy and signed up as fast as I could…  Turns out a Hawker Gnat is a mid 1970’s jet, a supersonic jet no less with full dual controls!  “The guy” turned out to be Skip Holm, 5 time winner of the Reno Air Races, three tour Vietnam F4 jock and and Stealth fighter pilot.  He did the flying in the movie “Hot Shots” which used several Gnats with “The Navy” painted on the sides.  (there’s some geology coming up..really).

Several of these jets had been surplussed from the RAF and sold to American doctors and lawyers.  Previously some of them had flown with the Red Arrows, the RAF equivalent of the Blue Angels.  Skip was the only guy with a letter of authorization to instruct these owners, and was selling instruction by the hour, basically for the cost of the fuel, an unbelievable deal.   So when I got there, Skip, who was still in the Reserves at the time, said “this thing doesn’t have much gas, so we can basically do two things, either go out to Edwards and make a boom (go supersonic), and come right back outa gas, or do ~ 45 minutes of acro over the Mojave and come back outa gas”.  Being still in the military, he could get permission for supersonic flight over Edwards, the only place in the US where you can do that.  Cool as it would be, Mach 1 is now just a number on a dial, so I went for the acro.  So we took off in this very little jet (you can look down into the cockpit standing on the ground).  It was astounding, we climbed out at a 30-40 degree angle to stay under the 25o knot speed limit (under 10,000 ft in most of the world).  To get to 10,000 ft took like a minute or two I think.  We headed north from Van Nuys over the mountains to the Mojave…. On the way there, Skip says “do you hear that?”  Confused, I said “what?”  As if I would know anything about the sound the Gnat should or shouldn’t make…  He thought the gear doors maybe had not closed all the way.  “Roll us inverted and I’ll cycle the gear” he says, thinking that cycling the gear  inverted might work. I’d had one acro flight in my life, but there you go, so I took the stick and over we went and held the nose up with some forward stick while Skip started the gear extension cycle.  Turns out this is very slow in the Gnat so we were just hanging there when I looked up (down) and saw were were over the San Andreas fault, very clearly obvious… He noticed it too and said “hey you’re a geologist, isn’t that the San Andreas Faul184-a-1280t?”  “Why yes it is….” and proceeded to point out the evidence for right offset stream drainages and topography etc.  Oxygen mask and all, I gave a nice little talk on the San Andreas.  Apparently I was boring Skip because when the gear cycle was done and he said ” Well that’s enough of that shit, lets go flying”  He took the stick back and pulled to the vertical, rolled 180 and down we went to the town of Mojave.  He started cackling and said “they can’t see us over here!”  We were now behind the mountains, and the LA controllers couldn’t see us….By the time we got there at 98% power (a few seconds), we pulled out pretty dang low at nearly 500 knots and buzzed the town…  We proceeded to have a great time doing acro over the desert, I got to fly some of it… Was awesome beyond words, and pretty quiet, you could hear wind noise on the canopy while the engine was sort of a hum.  Much quieter than a piston airplane, most of the sound was behind us.  All too soon we headed back… We taxied in with the low fuel light glowing, and shut down, so ending my very favorite geology lecture ever!  I see Skip at the Reno Races some years (he had a winning streak in Dago Red quite a few years running and holds the lap record at 507 mph) and for some reason he still remembers the “geology guy” who almost (but not quite) hurled in the Gnat while talking about the San Andreas Fault.

Written by eqgold

December 10, 2014 at 3:40 am

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MH 370

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It’s hard not to get sucked into the Maylasian 370 story at some level… Although I mostly work on earthquakes, I started out and still am a sonar and seafloor mapping guy, so am interested in how it will be to search for this airplane.  The pinger contacts were on the west flank of Wallaby Ridge, also known as the Zenith Plateau.  Unfortunately this is a very rough area of seafloor that has never been mapped, much like most of the worlds oceans.  When you look on Google Earth, you get the impression that the ocean floor has been mapped everywhere, and in a way that is sort of true.  The Google earth image comes from Satellite altimetry, mapping the ocean surface.  Oddly, there is topography on the surface of the ocean caused by the gravitational pull of the seafloor mountains and trenches below. So mapping the surface gives you a sort of “pseudo gravity” map, which can then be converted to bathymetry with enough ground truth.  It looks great from a distance, but up close, you see that the smooth rolling hilly topography isn’t real, it’s mostly noise from the low resolution of the data.  Real mapping of the seafloor requires ships and underwater vehicles, and is very, very slow (and expensive) which is why it hasn’t been done globally.

Image

 

The pinger contacts from MH370 still leave a large area to search, but at least it’s possible, where without them, it was nearly hopeless.  The problem now is that the terrain there is very rough.  Even though it’s ~ 100 million years old, it has very little sediment cover, a few 10’s of meters most likely, of microfossil “ooze”.  the few swaths of multibeam sonar data nearby show a very rough terrain that will make finding even an intact airplane difficult, and there’s not much chance it’s intact.  A landing like the “miracle on the Hudson” might have been possible in perfect weather and a good pilot, but more likely the airplane is in small pieces.  Finding such pieces in a background of a mountainous, hard, rough, rocky bottom is a sonarmans nightmare.  There isn’t much contrast between the metal and the rocks from the sonar’s eye, and so you’d have to hope for a big recognizable piece to appear, like a wing.  If not, they will likely be chasing many many possible targets, and trying to photograph them with the AUV cameras, or with ROV cameras.  Hopefully they will get more vehicles there, as the one small AUV has a huge job.

One of the strangest stories in aviation history may take months, or even years to be told, but I think it will be told.

Written by eqgold

April 16, 2014 at 9:25 pm

Well, not completely dodged…

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While casualties and damage from the 8.2 quake near Iquique were thankfully light thanks to the smallish tsunami and good Chilean building codes, the local fishing fleet was heavily damaged.  Iquique is mostly a mining town, and the port there is a mostly man made fill expanding on several rock islands just offshore.  In the lee of this port facility, were numerous small fishing boats that were trapped in the open ended roadstead when he tsunami arrived.  I doubt the local fishermen would call the damage light.

Image

Fishing boats washed ashore by a tsunami sit in the waters of Iquique, Chile, on Wednesday, April 2. A magnitude-8.2 earthquake struck off the coast of northern Chile on Tuesday, April 1, triggering small landslides and prompting evacuations of coastal areas. At least six people were reported dead.

Wrecked boats in Iquique (AP photo)

This again reminded me of what would probably be a similar result to an earthquake of this size in the Pacific Northwest.  While we are well behind in preparedness, at least we know what to do.  Finding the will and the money is another matter.  But fishermen around the world are not so easily moved to higher ground, or at least their boats and livelihoods are not.  The same is true here in the northwest, in Japan, in Sumatra and wherever a subduction zone underlies the coast.  In first world countries, the answer is typically insurance, because there is no known cure for this problem. Well there is one cure, practiced in Japan, and that is massive tsunami walls and gates in some of the rivers and harbors. Elsewhere, not so much.

https://i1.wp.com/walrus.wr.usgs.gov/tsunami/japan/images/m-s4.jpg

River gate in Minami-Sanriku (USGS)

Written by eqgold

April 3, 2014 at 4:51 pm

Dodged a Bullet

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It looks like the Chileans and southern Peruvians dodged a bullet in the northern Chile seismic gap. The 8.2 earthquake yesterday didn’t fill the gap, and the tsunami maxed out locally at ~ 2.3 m or so. Some damage to the airport and container facilities at the mining port of Iquique, and a few casualties. Otherwise, the widespread evacuations were largely not needed, and damage was light.  The workshop I was at in Santiago in late January was focused on this exact spot, which probably was near the site of an M9 earthquake in 1868.  After Sumatra and Tohoku, areas previously though unlikely to generate M9 earthquakes are now suspect, and the not very well known 1868 Arica event is an example of a very large earthquake that never fit the older seismological models.

The 1868 Arica event generated a 12-16m tsunami locally, and one up to 7m in New Zealand!  Yikes.  But given the likely slip deficit, that is the seismic gap is not filled, there remains some possibility of another large event in the near future, triggered by this one and distinct from the aftershock sequence.  Something like this may have happened with two events in 1868 and 1877.

File:USS Wateree (1863).jpg

The focal mechanism for the April 2014 event is as expected, a shallow thrust well aligned with the strike of the Nazca-S. America megathrust:

 

April 1, 2014, NEAR COAST OF NORTHERN CHILE, MW=8.1

Meredith Nettles
Goran Ekstrom

CENTROID-MOMENT-TENSOR  SOLUTION
GCMT EVENT:     C201404012346A  
DATA: II LD IU DK CU MN IC G  GE
 KP 
L.P.BODY WAVES:159S, 393C, T= 50
MANTLE WAVES:  159S, 451C, T=200
SURFACE WAVES: 142S, 199C, T= 50
TIMESTAMP:      Q-20140401232631
CENTROID LOCATION:
ORIGIN TIME:      23:47:29.1 0.1
LAT:19.77S 0.01;LON: 70.98W 0.01
DEP: 21.9  0.4;TRIANG HDUR: 26.9
MOMENT TENSOR: SCALE 10**28 D-CM
RR= 0.940 0.004; TT=-0.037 0.002
PP=-0.903 0.003; RT= 0.595 0.023
RP=-1.270 0.030; TP= 0.201 0.001
PRINCIPAL AXES:
1.(T) VAL=  1.702;PLG=61;AZM= 58
2.(N)      -0.024;     6;    159
3.(P)      -1.678;    28;    252
BEST DBLE.COUPLE:M0= 1.69*10**28
NP1: STRIKE=357;DIP=18;SLIP= 109
NP2: STRIKE=157;DIP=73;SLIP=  84

            ########---           
        ---#############---       
      -----###############---     
    -------#################---   
   --------##################---  
  ----------##################--- 
  ----------#########   #######-- 
 ------------######## T #######---
 ------------########   #######---
 -------------#################---
 ----   -------################---
  --- P --------###############-- 
  ---   ---------#############--- 
   ---------------###########---  
    ---------------#########---   
      ---------------######--     
        --------------##---       
            ---------##           

Full Circle!

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It’s a big Deal!  That’s what a 2nd grader shouted when the assembly of K-5 kids were asked why worry about earthquakes when they are so rare?  This was yesterday at Central Elementary School in Albany, a 100 + year old URM school which has just been retrofitted with shear walls, a steel fire escape and other features to make it more earthquake resistant.  There are about 1000 schools in Oregon that fall into this risky category in earthquake country.  So far about 13 have been upgraded…. A long way to go, but it’s a start.

When I first came to OSU as a grad student, I wasn’t sure what aspect of geology I wanted to gravitate too, but after a couple of years, active tectonics, and later earthquakes rise to the top for me, as things we could observe directly, and also as things that actually mattered to people, which seemed like a plus, though not a requirement for me.  As time went on, and I started working on the Cascadia subduction zone, it was an odd enigmatic place seemingly devoid of earthquakes, and that alone made it interesting.  Then the evidence for past great earthquakes began to come out, which answered some questions but raised others.  The enigma was still there, the lack of small earthquakes, even though the riddle of the absence of any earthquakes faded.   When Hans Nelson and I started working on paleoseismology, it became more and more clear that regular and very large earthquakes punctuate the recent history in Cascadia.  I bought earthquake insurance.

The earthquake story evolved, but remained a scientific issue for me until 2004, when the 2004 earthquake and tsunami hit Banda Aceh, Thailand and places all around the Indian Ocean. In the blink of an eye, this was no longer academic, and there I was talking to CNN on live TV from the wave lab the day after Christmas.    Few had ever actually seen a large destructive tsunami and lived to tell about it, let along watch it on TV.  But like millions of others, I watched it, and the reality of it was there for all to see.

Suddenly,  Cascadia was no longer academic either.  8 years later, we put the finishing touches on the paper that pulled together a decade of paleoseismology and calculated new odds for earthquakes.  The numbers got bigger.  The enormity of the Pacific Northwest having to actually do something to prepare for this coming earthquake became much more apparent.  The Tohoku earthquake put triple exclamation points on it.

Two years ago, a parent in Portland sent me an email asking about 1906 URM school her daughter goes to might be a problem in an earthquake.  She said a retrofit was planned but not completed and she felt she was getting the run round from school officials.   I told her what any earthquake person would, yes it’s a problem.  I suggested she bypass the local officials and write some letters to people starting with state legislators on up.   She did better than that  and started an organization, and Amanda Gersh and Ted Wolf became involved and instrumental in pushing for changes. Two years later, a bond measure for seismic retrofit passed to retrofit schools on Portland.

Then yesterday, at Central Elementary School, I went to see  the dedication of the seismic retrofit and said a few words to the kids along with the folks who made it happen.  It was pretty cool really to see this come full circle.

Written by eqgold

April 26, 2013 at 2:56 am

Posted in Uncategorized

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