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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

#73
post #45

Earlier quoted context omitted.

> 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.

Also, some tables, particularly heavy wooden and metal tables, can withstand lots and lots of weight. Hiding under them can help you avoid getting your skull bashed in by a falling slab of concrete.

The one biggish one I went through was in Seattle, where I was in a startup. We had cheap IKEA desks, which barely held the computers. I bolted for the door, which was the wrong thing to do in a brick clad building. Thankfully, we were on solid ground on Capitol Hill, not the fill in Pioneer Square, so I didn't get hit by falling cornice.

Re: New Zealand earthquake: Tsunami follows powerful tremor

#74
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.

Tsunami waves have an extremely long period. A good surfing wave forms when a swell 2-5 m amplitude with period 13-24s when it starts to feel the bottom of the ocean.

The amplitude of the tsunami wave in the open ocean is much smaller than wind-generated swells but they can have periods of 60-70 minutes so they are more of a surge that just keeps coming when they hit land, and as you say when they start to feel the bottom they stand up and the large volume of water in the wave makes it stand up larger and more powerful than you would expect for a smaller amplitude swell.

Every wave has a peak and a trough and the trough of the tsunami wave is what causes the water levels to recede so drastically before the wave hits.

Geographic features like valleys that get narrower and narrower will cause the same volume of water hitting the coast to make a much more drastic change in water level

Re: New Zealand earthquake: Tsunami follows powerful tremor

#77
post #8

Can someone please edit the title? And wow, this looks heavy. I hope everyone is well.

There's that word again. "Heavy." Why are things so heavy in the future? Is there a problem with the Earth's gravitational pull?

It's surfer slang, elements of which have made their way into a lot of the English spoken in NZ, Oz and SA.

Re: New Zealand earthquake: Tsunami follows powerful tremor

#78

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…

Currently in Wellington. Was fucking shaky, seriously thought the building was about to collapse. This was ~500 km from the epicenter.

~200km?

Also in Wellington, and it's work from home day today here while engineers check the building for damage.

Re: New Zealand earthquake: Tsunami follows powerful tremor

#79
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.

Imagine the energy stored by lifting a kilometre-high column of water 5cm. Now imagine how high that energy can lift a 5m column of water once it reaches the coast. Obviously there is the 1/r dissipation because the circumference increases, but still, deep water lifts like this can cause a massive surge at the coast.

Re: New Zealand earthquake: Tsunami follows powerful tremor

#80

Earlier quoted context omitted.

There's that word again. "Heavy." Why are things so heavy in the future? Is there a problem with the Earth's gravitational pull?

It's surfer slang, elements of which have made their way into a lot of the English spoken in NZ, Oz and SA.

He is quoting the movie "Back to the Future"

http://www.imdb.com/title/tt0088763/quotes?item=qt0416301

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