Sorowako Earthquake - 2011-02-15T1334GMT

[BigH]

All:
Just had a "significant" earthquake last night - while watching "The Closure". Wife starts screaming; everything shaking, bookcase fall over, pictures off walls, etc. Lasted about 20 seconds. Understand it is about 6.1 in magnitude. Interesting experience. Lots of little tremors subsequently; some lasting up to 5 seconds; rattling windows.

From USGS:

http://neic.usgs.gov/neis/bulletin/neic_b0001eez_l.html

Our house is at S2deg 31.03' ; E121deg 20.9'

I'll post a few snaps of the house later - - -

 

[Ron]

Geez BigH...looks like the epicenter was in your back yard! Glad you and family OK.

 

[Ron]

Roughly 3 to 4 miles southeast of you. That's a bit close!!

 

[BigH]

Understand that a study was done and determined the earthquake we experienced was 0.24g. Larger than they use in Vancouver.

 

[Ron]

BigH...what is the frequency of occurrence?

 

[dgillette]

Maybe that fellow in Oakland was only off by a few days on the end of the world.

Any dams in your neighborhood? I'm always looking for performance data, even if only eyeball observation.

 

[BigH]

Dave - we are building the third dam on the Larona River - just finished topping off and plan to water up towards the end of June. Designed, if I remember correctly, for something like 0.6g. As far as I know, nothing experienced any trouble - a few cracks - but while basically the same magntitude as that in Christchurch (would we be allowed to have a city called that - but that's for another time), we had no damage or as far as I know any injuries . . .

Just last night after we watched American Idol (on 12 hour delay), we had a minor quake that had the house shaking for about 10 seconds . . . not nearly as strong as the one we had in the OP. Guess they didn't want Scotty to win . . . .

Ron - we had minor aftershocks for about a month afterwards - the biggest being about 1/2 hour after the main one. Now they are about a month apart. We have a lot of "barely peerceptable" ones.

 

[dgillette]

Historically, well-compacted embankments on good foundations have always done well with loadings quite a bit worse than 0.24. I assume you are using 825s or something comparable for your core, and large vibratory rollers for your filter and drain zones, so I would have predicted only very minor deformation.

Apparently there has not yet been a geotech investigation of that Fujinuma Pond (dam) that failed in the big one; probably they have other priorities. It was started in the 1930s and completed after the war, times when Japan quite probably did not have lots of big sheepsfoot rollers. From that and some photos I've seen, I would bet that liquefaction of foundation and/or embankment was the culprit. In fact, I offered to bet my car against moe333's car. He has not accepted so far.

DRG

 

[BigH]

The one dam is RCC - the one we are building was supposed to be RCC but for many reasons I'd go over with you and a beer or two, it turned out to be low cement conventional mass concrete - carpi membrane on the backside; waterstops, galleries, etc. in the dam proper. Spillway goes over the powerhouse!

 

[moe333]

Dave, I agree, Fujinuma Pond (dam) has all the signs of a liquefaction failure. I wouldn't bet you on that one, and I doubt you would want my car.

 

[dgillette]

Mine is the sort you see advertised on Craig's List, "Runs good. Doesn't drip oil. Will trade for outboard motor or 2 hogs."