5.9 in Christchurch, effing scary. Was a biggie.

Forums › Off topic › 5.9 in Christchurch, effing scary. Was a biggie.

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#1492164 14-Feb-2016 18:37

JWR:

Fred99:

surfisup1000:

5.7 -- doesn't sound that big but everyone is saying it was really big.

I guess quakes of similar reported strengths can have different effects at the ground level -- depending on depth and underlying geology.

The immediate questions will be around that school they were trying to close underneath some cliffs near sumner... and , in general, buildings on and below the cliff. Look pretty dangerous to my untrained eye.

The school (Redcliffs) is well forward of the cliffs. The Feb 2011 ground shaking intensity was 5-10x stronger than the shake today - yet here was no rockfall in the school grounds.

The school is being closed for reasons other than EQ risk - that's just an excuse. The same government closing down the school will have no problems allowing the land to be sold for housing development etc.

Problem is threshold of risk. If you were an engineer who had to sign off to say that in your opinion there was no risk, you'd likely hesitate, in the same way that you might be reluctant to say that central Auckland won't be blown sky high by a volcano.

Been a few more minor shocks too.

Bit of a shake just now.

That one was funny. Was watching news - TV1 - supposed "live" interview. It clearly wasn't a "live" interview at all.

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kiwirock

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#1492167 14-Feb-2016 18:48

surfisup1000:

5.7 -- doesn't sound that big but everyone is saying it was really big.

I guess quakes of similar reported strengths can have different effects at the ground level -- depending on depth and underlying geology.

The immediate questions will be around that school they were trying to close underneath some cliffs near sumner... and , in general, buildings on and below the cliff. Look pretty dangerous to my untrained eye.

I'm glad it wasn't bigger. I was just saying last week touchwood Chch hasn't had a decent quake latelty. There was quite a few decent quakes around the pacific ring over the last 3 weeks, and a Volcano getting quite active again in Japan and south of Australia. With that much activity Christchurch was usually the radar like the last few big ones.

Edit to include:

Over the last 30 days.

6.3 Chile
6.6 mexico
7.1 alaska
6.2 l.esperance rock (North of NZ)
6.3 indonesia
6.4 taiwan
7.2 russia

Not to mention scores of 5+ everywhere.

Volcanos that got media attention:

Sakurajima (Japan)
Mount Makaturing (Phillipines)
Karymsky volcano (Russia)
Big Ben- Heard Island in sub-Antarctica (Australia)
McDonald islands (neighbouring Heard Island)
Popocatepetl volcano in Puebla, Mexico

JaseNZ

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#1492170 14-Feb-2016 19:00

Fred99:

That one was funny. Was watching news - TV1 - supposed "live" interview. It clearly wasn't a "live" interview at all.

Haha was just saying that to the missus , bollocks that's live its not shaking her about.

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TwoSeven

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#1492171 14-Feb-2016 19:02

surfisup1000:

5.7 -- doesn't sound that big but everyone is saying it was really big.

I guess quakes of similar reported strengths can have different effects at the ground level -- depending on depth and underlying geology.

The immediate questions will be around that school they were trying to close underneath some cliffs near sumner... and , in general, buildings on and below the cliff. Look pretty dangerous to my untrained eye.

I got the feeling that after the previous quakes people kind of developed the equivalent to sea legs on a ship. People will offer an opinion on how deep something was and how far away just by the feel of the shake. We make a bit of a competition out of it to see who can guess the closest score before someone looks up the result, it helps divert attention sometimes.

For me, a 3 is not much different than a heavy truck going over a bump in the road nearby, a 4 is a bit of a shake or a jolt and a 5 is usually a bit of a rattle and wobble. What makes it interesting is when they go on for longer than normal like todays one. My memory isn't that good from the old quakes, but I seem to remember that the long duration ones used to sometimes pick up intensity half way through, so it can be interesting while waiting during the shaking to see if that happens or not.

There are also the really close ones, for example, having a 2.0 right underneath can make one jump just as much as a 4.0 a distance away. The close ones are interesting because the further away they are the more one can sometimes hear the approaching rumble so one can tell if they are worth giving further thought to, the close ones kind of sneak up unexpected.

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Djmixerdomo

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#1492235 14-Feb-2016 20:29

I was sitting on the beach at Rapaki and I though I was about to pass out or something when I was wobbling around. Then when I realised it was a quake I was looking around at the hills/cliffs to check for rockfalls, thankfully there were none unlike over at Godly head and Redcliffs.

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sen8or

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#1492835 15-Feb-2016 21:00

When the shaking was happening regularly in the 2010-2012 period, I used to be pretty good at guessing size and location.

Our DVD shop in Hornby had a sign on the outside, under 3.5 and it sounded like a truck going past, air movement but no real vibrations. 3.5-4.5 and it rattled a son on the outside of the shop, again though no real movement through the floor. It was only over 4.5 that you could feel it through the floor.

Close to location quakes are more sudden / sharp in nature, far away and it's like a wave.

That's how the one on Sunday felt out in Lincoln, like being on a boat in moderately rough seas, just a gentle up/down, nothing more. A little aurprised to be honest that it was as big as has been reported, but given we are 40 odd kms from the centre of the quake, it dispersed its energy pretty quickly.

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#1492885 15-Feb-2016 21:34

sen8or: When the shaking was happening regularly in the 2010-2012 period, I used to be pretty good at guessing size and location.

Our DVD shop in Hornby had a sign on the outside, under 3.5 and it sounded like a truck going past, air movement but no real vibrations. 3.5-4.5 and it rattled a son on the outside of the shop, again though no real movement through the floor. It was only over 4.5 that you could feel it through the floor.

Close to location quakes are more sudden / sharp in nature, far away and it's like a wave.

That's how the one on Sunday felt out in Lincoln, like being on a boat in moderately rough seas, just a gentle up/down, nothing more. A little aurprised to be honest that it was as big as has been reported, but given we are 40 odd kms from the centre of the quake, it dispersed its energy pretty quickly.

I wonder if Lincoln is directly behind the Sumner/Redcliffs hills, if so the hills bore the brunt of the energy in your path?

Djmixerdomo

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#1492901 15-Feb-2016 22:07

joker97:

sen8or: When the shaking was happening regularly in the 2010-2012 period, I used to be pretty good at guessing size and location.

Our DVD shop in Hornby had a sign on the outside, under 3.5 and it sounded like a truck going past, air movement but no real vibrations. 3.5-4.5 and it rattled a son on the outside of the shop, again though no real movement through the floor. It was only over 4.5 that you could feel it through the floor.

Close to location quakes are more sudden / sharp in nature, far away and it's like a wave.

That's how the one on Sunday felt out in Lincoln, like being on a boat in moderately rough seas, just a gentle up/down, nothing more. A little aurprised to be honest that it was as big as has been reported, but given we are 40 odd kms from the centre of the quake, it dispersed its energy pretty quickly.

I wonder if Lincoln is directly behind the Sumner/Redcliffs hills, if so the hills bore the brunt of the energy in your path?

Although the hills kinda between Lincoln and the epicentre of the quake, I think the it's just because Lincoln is 30+Kms away that resulted in it feeling very mild.

here's a quick map I made: https://i.imgur.com/4QPEIdp.jpg

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Fred99

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#1492916 15-Feb-2016 23:13

Isoseismal showing station near Lincoln, pga recorded there was 1.9% g.

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#1492978 16-Feb-2016 07:23

I was wondering, is the latest version of the building code - in general is it stricter in certain places like Chch vs everyone else or or does everyone use the same high quake standards

flyingdutchdude

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#1492984 16-Feb-2016 08:00

Fred99:

Isoseismal showing station near Lincoln, pga recorded there was 1.9% g.

Interesting map, thanks for sharing. Where did you locate the image?

This blog entry was enlightening too: http://info.geonet.org.nz/display/quake/2016/02/14/Large+quake+off+the+coast+of+Christchurch

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#1493031 16-Feb-2016 09:16

kiwirock:

surfisup1000:

5.7 -- doesn't sound that big but everyone is saying it was really big.

I guess quakes of similar reported strengths can have different effects at the ground level -- depending on depth and underlying geology.

The immediate questions will be around that school they were trying to close underneath some cliffs near sumner... and , in general, buildings on and below the cliff. Look pretty dangerous to my untrained eye.

I'm glad it wasn't bigger. I was just saying last week touchwood Chch hasn't had a decent quake latelty. There was quite a few decent quakes around the pacific ring over the last 3 weeks, and a Volcano getting quite active again in Japan and south of Australia. With that much activity Christchurch was usually the radar like the last few big ones.

Edit to include:

Over the last 30 days.

6.3 Chile
6.6 mexico
7.1 alaska
6.2 l.esperance rock (North of NZ)
6.3 indonesia
6.4 taiwan
7.2 russia

Not to mention scores of 5+ everywhere.

Volcanos that got media attention:

Sakurajima (Japan)
Mount Makaturing (Phillipines)
Karymsky volcano (Russia)
Big Ben- Heard Island in sub-Antarctica (Australia)
McDonald islands (neighbouring Heard Island)
Popocatepetl volcano in Puebla, Mexico

Kaiju activities...

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Fred99

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#1493050 16-Feb-2016 09:50

flyingdutchdude:

Interesting map, thanks for sharing. Where did you locate the image?

This blog entry was enlightening too: http://info.geonet.org.nz/display/quake/2016/02/14/Large+quake+off+the+coast+of+Christchurch

That was from USGS.

joker97: I was wondering, is the latest version of the building code - in general is it stricter in certain places like Chch vs everyone else or or does everyone use the same high quake standards

For houses, it's defined in zones (1-4) under NZS 3604 - simplified/modified map from BRANZ below: