OT- Peak acceleration in Christchurch quake was 2.2G!
Hanno
Posts: 1,130
Peak ground acceleration was measured at 2.2G- basically right under my house- see attached map- I live within the first circle.
Last year's devastating quake in Haiti which killed >200,000 "only" measured .5G.
Loma Prieta was 1.7- but very far from cities.
Christchurch's downtown, which may not reopen until Christmas, measured 2.0G- I think even New Zealand's very strict building code only requires building to survive 1.0G forces. Truly unprecedented.
I didn't have my propeller-powered quake sensor running (I posted about it 6 months ago)- but if I had, the sensor would have maxed out- it's only capable of measuring 2.0G...
Personal update- Family and building fine- some damage but repairable. Got water today, electricity several days ago. People starting to come back, hopefully school will reopen this week. I recorded my keynote presentation for http://www.robovirtualevents.com/ yesterday.
Thanks everyone for thoughts and help.
If you're really interested in helping out plan a visit to NZ later this year- would love to show you around...
Hanno
850 x 641 - 57K
Comments
Are you going to rebuild your prop quake sensor so it can go to 3G?
'Glad to hear that your family is okay, that the house is repairable, and that things are returning to a state resembling normalcy. Yours is the first technical data I've seen about the quake, and 2G is just hard to imagine. Was that a lateral or normal shake? For how long? Your house must have amazing construction, BTW!
-Phil
Might be time to rethink that ceiling ?
I listened online to several NZ radio stations after the quake.
It was interesting listening.
It must have been very scary when the quake hit!
The biggest one that I have been near was just 5.1, but was quite close to the surface. I wouldn't want to get any larger ones happening close by.
I was 10 yards fron a lightning strike, in a field once, hence the paranoia.
Take care.
Some years ago I was at a amusement park and rode on the 'spinning room', a cylinder about 15 - 20 feet across. You line up backs to the rubber coated wall and after they bring it up to sufficient speed, the floor drops down a couple of feet. I was so surprised I could hardly press myself away from the wall. Makes one feel terribly weak to hardly be able to even turn around while against the wall.
Good to hear your family was spared, and that the house survived. I'm always surprised how strong the forces of nature and disasterous events can be. Must feel good to have the services being restored. Amazing how dependent we become for all the devices that need water, electricity, natural gas, sewer, etc. And for us engineering/hobbyist types, to be without electric power for a week is quite frustrating.
I've been thinking about the 2.2G figure now that it's official- and it simply amazes me. I don't think a normal person experiences that type of force outside traffic accidents. Flying acrobatics you do pull some g's- for example at the bottom of a loop you're probably close to 2G's.
I haven't seen characteristics of the force- but would imagine it to be ~.1sec lateral movement. Accelerating at 2.2G for .1sec gets you to 7.8km/h- roughly running speed. So, imagine your house accelerating to running speed for .1sec, stopping, then the other way- several times per second. I don't remember what it felt like- was running like hell to make sure rest of family was safe.
Most accelerometer sensors can be switched between 2G and 6G maximums- so it's easy to fix that- although I doubt we'll see another of that magnitude in our lifetime. I've seen one paper that said 2G forces were likely to be felt at the epicenter of a 8.6G quake!
I built a big portion of my house by myself- to NZ standards with help of a very good engineer and 11 inspections to keep me honest. Had to hire an electrician to connect the panel and plumber to connect sewage- did pretty much everything else by myself. I think it survived because:
- it's supported by timber poles which are sunk in concrete into very very solid soil- I cursed at it while digging the foundation, but very happy now
- it's lightweight- no tile roof, just "tin" coated to look like tiles.
- cladding is "linea" concrete/fiber weatherboard- no damage whatsoever- it's quite flexible but doesn't crack/expand with heat, so doesn't need to be repainted.
- all walls are light, but very strong: 2x6 studs, metal tape for triangles, and fiber backed plaster board.
- I'm very lucky
Hanno
If I hadn't been over about 8 months ago then I would. Am planning to come back but may have to wait a few year$..
People,
NZ is an amazing place - the people are lovely, and the scenery is spectacular. It is VERY easy when driving arond to see why they made Lord of the Rings in the south island.
If you're going to do a holiday OS this year - then I would _strongly_ recommend NZ.
Paul
Here's a way to put 2.2g in perspective. I've owned two Corvettes, both back when Chevrolet thought saving gasoline would sell more of the world's #1 sports car than would performance. Neither of my 'Vettes would do 1.0g. (I can't remember WHAT g number was assigned to them.)
The HIGH performance Corvettes have numbers like 0.92 and 1.10.
Hanno's house is faster.
--Bill
ps Actually, "quicker" is more correct than "faster", but "faster" sounds better.
Pacman-
Glad you liked NZ. Wife and I first came here during our honeymoon- loved it so much we moved here from California. Even with quakes I can't think of a better place to raise kids and enjoy life. Just came from a community bbq- lots of kids running around, live music, good time.
Hanno
Not another one!
http://www.christianpost.com/news/multiple-earthquakes-hits-new-zealand-51110/
Hope all is well.
Maybe time to move over to Oz. There are good buddies over there and don't seem to have the same ground shaking events.