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New Zealand earthquake: Tsunami follows powerful tremor

bbc.co.uk

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Re: New Zealand earthquake: Tsunami follows powerful tremor

#51

Post by jamestnz »

blueprint wrote: post #44

Anyone know of a group or website which is tracking the incidence and intensity of earthquakes over time?

Not sure if suitable for your purposes, but GeoNet. They use a network of digital seismic stations. Whenever seismic waves propagate, doing a time-analysis of when they passed under each station can tell you where the quake occurred. This is augmented with crowd-sourced "felt reports".

Literally within seconds of a shake, the preliminary report hits their website, and its confidence level increases over the next few minutes as more data reports in.

I believe their online (open) data set now catalogs all NZ-region earthquake events from like the last 80 years or something. Pretty neat.

Here is the page for the big one of 6 hours ago, not to be confused with the dozens of also-large aftershocks following it:

https://www.geonet.org.nz/quakes/region/newzealand/2016p8580...

Re: New Zealand earthquake: Tsunami follows powerful tremor

#52

Post by idlewords »

avar wrote: post #45
toomanybeersies wrote: post #26

Currently in Wellington. Was fucking shaky, seriously thought the building was about to collapse. This was ~500 km from the epicenter. We were evacuated and let back in. All the planning in the world doesn't prepare you for the real thing, the first thing you're meant to do is keep calm, and I sure as hell didn't. I sprinted right the fuck out of my apartment building, I have 4 levels above me, hiding under a table w…

> I have 4 levels above me, hiding under a table > wasn't going to do shit to save me [...] food > has fallen off all the shelves, The advice to hide under tables isn't meant to save you from the entire building collapsing, but from injuries sustained from stuff falling off shelves & the non-structural parts of your roof collapsing.

"You're doing it wrong," only for earthquakes.

Re: New Zealand earthquake: Tsunami follows powerful tremor

#53

Post by blueprint »

jamestnz wrote: post #51
blueprint wrote: post #44

Anyone know of a group or website which is tracking the incidence and intensity of earthquakes over time?

Not sure if suitable for your purposes, but GeoNet. They use a network of digital seismic stations. Whenever seismic waves propagate, doing a time-analysis of when they passed under each station can tell you where the quake occurred. This is augmented with crowd-sourced "felt reports". Literally within seconds of a shake, the preliminary report hits their website, and its confidence level increases over the next few…

I'm more looking for a study that tracks an increase or decrease in their intensity and magnitude over time. I would need to scientifically study and analyze the data at the link you kindly shared in order to see that.

Re: New Zealand earthquake: Tsunami follows powerful tremor

#54

Post by Freestyler_3 »

EdwardDiego wrote: post #39
zoltrain wrote: post #29

I'm from Christchurch, contacted family there. There's been mass evacuations from the coastline. Tsunami's have started but they can last for hours. Kaikoura has already had a a surge measured 2.5m, if this is the case the waves will get worse before they get better. But NZ is pretty prepared for these things, so hopefully everyone scampers to the safe distance from the coastline. I worry about the Chatham Islands, t…

No, that 2.5m high one was the worst of the waves. http://images.geonet.org.nz/tsunami/plots/latest/detide.png It was most likely caused by a movement of sediment into the Hikurangi Trough.

Then why is it still reported that waves 3-5 meters are expected?

Re: New Zealand earthquake: Tsunami follows powerful tremor

#56

Post by Freestyler_3 »

doldge wrote: post #30

Cross-posting from my FB feed: Here's some of the interesting stuff I've found on the internet about today's earthquake (that they're now calling a 7.8): 1) real-time Buoy data, for helping to determine the likelihood of a Tsunami: http://www.ndbc.noaa.gov/ Interestingly, the quake only caused a tiny change in the sea level (in the region of 5 cm's) but the expected swells on land are in the region of 3-5 meters. I b…

1) I think it was because the 5cm height is backed by a huge width, when crawling towards the land slope creates a very strong (not necessary high) wave that just keeps pushing forward.

Re: New Zealand earthquake: Tsunami follows powerful tremor

#57

Post by r721 »

r721 wrote: post #14

Better resolution map: https://pbs.twimg.com/media/CxJjRotUUAAJK-w.jpg:large (from https://twitter.com/NZcivildefence/status/797809307597213696 ) Some tweets with photos: https://twitter.com/ThomasMeadia/status/797806928520880128 https://twitter.com/ThomasMeadia/status/797809032635420672 https://twitter.com/HenryMcMullan/status/797813785461334017

Map updated: https://pbs.twimg.com/media/CxKErQkUQAArm_4.jpg:large (from https://twitter.com/NZcivildefence/status/797846187197902848)

Re: New Zealand earthquake: Tsunami follows powerful tremor

#58

Post by zoltrain »

Freestyler_3 wrote: post #54
EdwardDiego wrote: post #39

Earlier quoted context omitted.

No, that 2.5m high one was the worst of the waves. http://images.geonet.org.nz/tsunami/plots/latest/detide.png It was most likely caused by a movement of sediment into the Hikurangi Trough.

Then why is it still reported that waves 3-5 meters are expected?

Civil Defence are doing their job, getting people away from the coastline. There maybe Tsunami's there may not be, better not to take any risks. Must be protocol when any of the Tsunami alarms are triggered.

Re: New Zealand earthquake: Tsunami follows powerful tremor

#59

Post by idlewords »

EdwardDiego wrote: post #42
idlewords wrote: post #25

Earlier quoted context omitted.

A big problem in the Christchurch region is liquefaction. There's not much earthquake codes can do to keep the ground from turning to goop.

It wasn't liquefaction that killed people though. That is what removed a large portion of the housing stock in the east, however.

You're completely right. Earthquake codes save lives, but in liquefaction zones, the structures may be unlivable afterwards even if they're completely intact.

Re: New Zealand earthquake: Tsunami follows powerful tremor

#60

Post by DanBC »

doldge wrote: post #30

Cross-posting from my FB feed: Here's some of the interesting stuff I've found on the internet about today's earthquake (that they're now calling a 7.8): 1) real-time Buoy data, for helping to determine the likelihood of a Tsunami: http://www.ndbc.noaa.gov/ Interestingly, the quake only caused a tiny change in the sea level (in the region of 5 cm's) but the expected swells on land are in the region of 3-5 meters. I b…

There are some videos on Youtube of tsunami from various places.

Here's one from Japan: https://www.youtube.com/watch?v=j0YOXVlPUu4

https://www.youtube.com/watch?v=5IKIazZc-a8

It doesn't look like much is happening at the beginning. It doesn't look like a wave, or a front of water. But it's a lot of water, and it's fast.

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