Busytown by Jolisa Gracewood

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Busytown: The shakes

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  • ChrisW,

    Why that aftershock at 7.49am felt so much worse than suggested by its magnitude of 5.1 -

    I've been off-line and only just heard of this one so missed the actual coordinates, but Geonet now puts its source as 6 km deep "10 km NW of Diamond Harbour" - an odd reference point, they might have said "2 km SE of the Square" (it won't really be that precisely located, but still).

    So - inverse square law again - the intensity of the shaking felt in central-eastern Christchurch say 7 km from the source (hypocentre) of the earthquake would be expected to match that of a magnitude 6.1 earthquake 40 km away.

    Earthquake Magnitude is always only part of the story, not very meaningful on its own.

    Gisborne • Since Apr 2009 • 833 posts Report Reply

  • Sacha,

    Just the thing to shore up that saggy kitchen, provided he keeps his yap shut

    The hair alone would make a handy draught excluder for a school hall or other vital social infrastructure

    Ak • Since May 2008 • 16627 posts Report Reply

  • Steve Barnes,

    Something not quite right in that arithmetic there Sofie. Southerly might say it per units of atomic bombs, which I'm looking forward to.

    A rule of thumb equivalence from seismology used in the study of nuclear proliferation asserts that a one kiloton nuclear explosion creates a seismic signal with a magnitude of approximately 4.0. This in turn leads to the equation

    Mn = 2/3log10 mTNT/Mt +6

    where mTNT is the mass of the explosive TNT that is quoted for comparison (relative to megatons Mt).

    So, what's that in Elephants farts?.
    :-)

    The wireless north ;-) • Since Dec 2006 • 4824 posts Report Reply

  • Rich of Observationz,

    According to Wikipedia's handy table, 5.1 is an atomic bomb that didn't really work right. (500 tonnes TNT)

    Of course, the wielders of nukes don't typically bury them kilometers underground.

    Back in Wellington • Since Nov 2006 • 4450 posts Report Reply

  • Ian Dalziel,

    SNAFU... status quo really - and I hate heavy metal!
    we are all fine, but the Lyttelton Rd tunnel is closed apparently - they are saying take the Evans pass road via Sumner
    - don't think I'd be game to do that route...
    as that last shock was centred near the port hills...

    and I have to say the Martyrdom of Bob Parker is beginning to wear thin - he's going on in the paper (and on his extended Campbell Live Ad last night) about doing 20 hour days - but is not being a team player - he is only one elected official and he is not delegating to anyone else or sharing the load - the very thing that got him so unpopular - he just doesn't learn - a stretched sleep deprived mayor is no good to anyone...

    Christchurch • Since Dec 2006 • 4892 posts Report Reply

  • David Hood,

    Since we've moved into the Earthquakes measured in atomic bombs, I thought I'd mention I found out last week about the banana equivalent dose for measuring radiation.
    wikipedia

    Dunedin • Since May 2007 • 884 posts Report Reply

  • ChrisW,

    Resident geologist here. The main earthquake was from abrupt movement on a fault analogous to the Hope Fault, more-or-less parallel to it and with the same sense of movement. So the surface fault trace is aligned west-east from Greendale to near Rolleston, and the fault-plane dips to the north towards Darfield. The north side of the fault moved eastward up to 4 m relative to the southern side, and also a little upward, up the fault-plane.

    This new fault is an outer part of the Australian/Pacific plate boundary system that links between the Alpine Fault in the SW and the Hikurangi Trench off the east coast of the North Island. The plate boundary in this form is only a few million years old, much younger than the Gondwana story. The new fault may really be 'new' but more likely just newly discovered in that it has previously undisturbed 16,000-year-old gravels overlying it, demonstrating there had been no movement on it for 16000 years (which does not mean "it last moved 16,000 years ago").

    The aftershocks are from secondary release of strain within crustal rocks (not surface gravels) caused by the main earthquake. This last intense one under Christchurch is right on a continuation of the observed faultline. I think this is a good sign, in that it's 20 km away from the eastern end of the new surface break, and makes it seem less likely that there will be a fundamentally bigger one from propagation of the original fault displacement further along the fault plane.

    Gisborne • Since Apr 2009 • 833 posts Report Reply

  • Tim Michie,

    It certainly was reassuring to hear how calm Emma sounded reviewing this morning although I'm sure she could've made a conribution on swearing too.

    Auckward • Since Nov 2006 • 561 posts Report Reply

  • Emma Hart,

    It certainly was reassuring to hear how calm Emma sounded reviewing this morning although I'm sure she could've made a conribution on swearing too.

    Dude, this isn't the first time I've said this, and it won't be the last, but that's not me.

    Christchurch • Since Nov 2006 • 4364 posts Report Reply

  • Sacha,

    That voice is nowhere near witty and saucy enough

    Ak • Since May 2008 • 16627 posts Report Reply

  • Kyle Matthews,

    Of course, the wielders of nukes don't typically bury them kilometers underground.

    At Mururoa they dug up to a kilometer under the atoll to set off 147 nuclear bombs over a 20 year period.

    Since Nov 2006 • 6166 posts Report Reply

  • Tim Michie,

    Not you.

    Apologies.

    Auckward • Since Nov 2006 • 561 posts Report Reply

  • Hilary Stace,

    Emma, it was a trifle confusing that Kathryn Ryan mentioned that that Emma Hart was in the Wellington studio with her, while you had just written about being in bed in Christchurch.

    Wgtn • Since Jun 2008 • 2077 posts Report Reply

  • Craig Ranapia,

    Where would we be if we couldn't say "How 'bout that weather eh" :)

    How about Conversation the Jane Austen Way:

    In the present instance, she confessed and lamented her want of knowledge, declared that she would give anything in the world to be able to draw; and a lecture on the picturesque immediately followed, in which his instructions were so clear that she soon began to see beauty in everything admired by him, and her attention was so earnest that he became perfectly satisfied of her having a great deal of natural taste. He talked of foregrounds, distances, and second distances—side-screens and perspectives—lights and shades; and Catherine was so hopeful a scholar that when they gained the top of Beechen Cliff, she voluntarily rejected the whole city of Bath as unworthy to make part of a landscape. Delighted with her progress, and fearful of wearying her with too much wisdom at once, Henry suffered the subject to decline, and by an easy transition from a piece of rocky fragment and the withered oak which he had placed near its summit, to oaks in general, to forests, the enclosure of them, waste lands, crown lands and government, he shortly found himself arrived at politics; and from politics, it was an easy step to silence.

    North Shore, Auckland • Since Nov 2006 • 11941 posts Report Reply

  • Emma Hart,

    Not you.

    Apologies.

    Oh, no worries Tim. It just happens kind of a lot.

    Christchurch • Since Nov 2006 • 4364 posts Report Reply

  • Martin Lindberg,

    How about Conversation the Jane Austen Way

    Jeez Craig! You need to put up a warning before posting Austen. I stopped before the first comma, but now I feel all stabby.

    Stockholm • Since Jul 2009 • 796 posts Report Reply

  • Joe Wylie,

    and I have to say the Martyrdom of Bob Parker is beginning to wear thin - he's going on in the paper (and on his extended Campbell Live Ad last night) about doing 20 hour days -

    The hagiography is rather in overdrive. I reckon those who are genuinely working overtime to create a semblance of meaning behind Mayor Bob's paper-thin 'personality' are tempting fate. Once you've performed your first apparent miracle it's foot to the floor exploiting the window of opportunity between that and your inevitable crucifixion.

    flat earth • Since Jan 2007 • 3477 posts Report Reply

  • dyan campbell,

    Of course, the wielders of nukes don't typically bury them kilometers underground.

    The Amchitka bomb test was set off nearly 2km deep.

    Time Magazine, 1971 Amchitka

    auckland • Since Dec 2006 • 595 posts Report Reply

  • Marcus Turner,

    Re quakes and bombs, a couple of pertinent animations:

    Quakes

    And

    Bombs

    Since Nov 2006 • 202 posts Report Reply

  • Danielle,

    Jeez Craig! You need to put up a warning before posting Austen. I stopped before the first comma, but now I feel all stabby.

    Hmph! That was a really funny paragraph.

    Charo World. Cuchi-cuchi!… • Since Nov 2006 • 3655 posts Report Reply

  • Joe Wylie,

    Well f*ck me I've been yellow stickered & must vacate.
    Goodbye sweet broadband.

    flat earth • Since Jan 2007 • 3477 posts Report Reply

  • Emma Hart,

    Well f*ck me I've been yellow stickered & must vacate.
    Goodbye sweet broadband.

    Oh Joe, that sucks. Good luck.

    Christchurch • Since Nov 2006 • 4364 posts Report Reply

  • giovanni tiso,

    What Emma said.

    Wellington • Since Jun 2007 • 7358 posts Report Reply

  • Jackie Clark,

    So sorry Joe, that really is terrible. Big loves to you and yours.

    Mt Eden, Auckland • Since Nov 2006 • 3123 posts Report Reply

  • 3410,

    Damn. Sorry to hear that, Joe.

    Auckland • Since Jan 2007 • 2618 posts Report Reply

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