Archive February 2011

Lyttelton earthquake peak ground acceleration Grant Jacobs Feb 27


A light post introducing two maps showing the difference in shaking in the September 4th and February 22nd earthquakes.

If you are looking for my news feed on the Christchurch/Lyttelton earthquake, I post comments updating news here; older comments can be found on an older post.

During the 22nd February Lyttelton earthquake my uncle’s bath, half-full with water, was thrown up in the air to meet the taps on the wall.

We’re held on this planet by gravity, 1 G’s worth.

Any force that throws things up upwards has to be greater than gravity’s pull downwards.

One way geologists measure earth movements is to record the acceleration in movements of the ground.

Acceleration is the amount of change in speed. You plant your foot on the pedal in a car, the rate at which the speed increases is acceleration.*

Peak Ground Acceleration (PGA) is the amount of acceleration of movement of the earth at the point recorded, reported as a percentage of gravity’s acceleration (9.80655 m/s2).

Below are the peak ground acceleration maps for the Sep 4th earthquake and below it the February 22nd earthquake that I found on the GeoNet website (click on the image to see the full images at the GNS website):

PGA values for Darfield September 4th, 2010 earthquake; map from GNS GeoNet website (cropped, with legend moved)

PGA values for Darfield September 4th, 2010 earthquake; map from GNS GeoNet website (cropped, with legend moved)

PGA values for Lyttelton Feb 22nd, 2011 earthquake; map from GNS GeoNet website (cropped, with legend moved)

PGA values for Lyttelton Feb 22nd, 2011 earthquake; map from GNS GeoNet website (cropped, with legend moved)

These maps show the peak ground acceleration at particular points (coloured boxes), with a few landscape features sketched in. The black lines are coastlines and rivers, the red lines roads. The CBD is roughly the area of the right-hand half of that bounded by the two red lines (roads) at 90˚ to each other at the upper-left of the sections of the maps I’ve shown.

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Forecasting space weather and capturing paper data Grant Jacobs Feb 27

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Sunday diversion from earthquake news with some space science – and a little reminiscing from my Ph.D. studies.

At the end of second of the two videos below Chris Davis refers to ’the space weather forecast’, hence my title.

Basically, he’s talking about the magnetic atmosphere of the earth and the influence of the sun on it.

As everyone here knows I’m not an astronomer (I’m a computational biologist), but Chris explains what he’s doing so well I’m getting the picture too.

In the first video he’d dug up old paper recordings of atmospheric activity. Scientists are fond of datasets in their field. Dataset have all the clues to the mysteries they’d like to dig into and solve. You hate to see the stuff get thrown away or sit there idle.

Chris ponders how to add years of paper (film) records to the modern digital ones. It’s a problem in many other fields too, and brings up issues of data formats–even electronic data formats age and present problems in time, something people in my field deal with from time to time.

YouTube Preview Image

Now that I think back, in a sense I’ve done a little of what Chris is up to here myself.

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Beautiful peaceful images Grant Jacobs Feb 25


If you’re shellshocked from all earthquake disaster reporting, these peaceful images may provide a little relief.

You can view the winners of the annual Wellcome Image awards either at the Wellcome Image Awards website (click ‘View the gallery’) or on this excellent BBC slideshow. The slideshow jazzes things up a little with sound and moving the images around, but the stills are superb on their own. You’ll also get more information about the images on the Wellcome site. Larger copies of the images can be seen by clicking on the images at the Wellcome site (and below). As a teaser, I’ve included two below.

Try guess what this before you click on the image to find out:

Credit: Kevin MacKenzie, University of Aberdeen, Wellcome Images.

Credit: Kevin MacKenzie, University of Aberdeen, Wellcome Images.

Or this:

Credit: Spike Walker, Wellcome Images.

Credit: Spike Walker, Wellcome Images.

6.3 earthquake in Christchurch Grant Jacobs Feb 22


This is page contains collected snippets and links for this event from the time they were found. Please bear in mind the advisories are for the time written. I’ve left them as a record of how things unfolded. Later corrections or updates are, for the most part, enclosed in square brackets, minor typos excepted. (This note added 24th Feb., am.)

Just a quick note to alert New Zealand readers: a large earthquake, reported to be magnitude 6.3 has occurred centred 10km south-west of central Christchurch at a depth of 5km. Early reports are of some buildings down and concerns over possible deaths. The brief newspaper report out thus far says that Christchurch hospital is being evacuated. [Reports later corrected this to one ward evacuated.]

Moving this to top temporarily:

@vodafoneNZ needs clear network through ALL NZ please. #eqnz #chch

That is, they’re asking people throughout the country to stay off the phone network unless it’s urgent. No mobile calls. Twitter is OK apparently. ~5pm: More recent requests are for people to limit themselves to texts. 22nd Feb., 9:30am: reports are the request to stay off mobile phones unless urgent still stands.

I will update this post as I get more news. Newer information is added to the bottom (sorry).

Best wishes to all in Christchurch.

(Disclosure: Christchurch is my hometown; my family lives there. My brother & partner have a baby due today, too.)

While of lesser magnitude than the September 4th event, today’s event is much closer to the centre of the city (~10km vs. ~45km) and shallower (~5km vs. ~10km).

1:52pm: Calls are going out to limit phone calls & use text if possible. Wish they’d come clean out and say if texts are OK. (I want to contact my family!)

Top of Cathedral gone: (Will put this up later.)

Update: more of the cathedral has fallen since in an aftershock.

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Message to Otago Daily Times: homeopath is not a sound career option* Grant Jacobs Feb 21


OPINION. Every now and then I see something in the paper that really annoys me…

The Otago Daily Times–locally known as the ODT–is a good newspaper, I wouldn’t be buying it otherwise, but even good papers mess up from time to time.


Why on earth has the ODT presented an homeopath in one of it’s on-going series of snapshots of people in different careers?

More importantly, perhaps, why does the presentation have no critical questioning?

The ODT starts it’s weekend employment vacancies section with an article presenting a series of questions and replies about a particular person’s job. I’ll assume the answers are written by the ‘interviewee’ for the purpose of this. (Rather than transcribed from an interview.)

John S. Carroll recently said that journalists’–and by implication, newspapers’–loyalty should be to citizens.

To me, this includes critically judging what they present.

Things that appear in print gain a certain amount of creditability merely by being in print in a reputable publication.

Shouldn’t statements of questionable creditability be questioned in order that the citizen is well served?

Should a journalist not question the creditability of homeopathy in questioning a homeopath? Should this even be offered as a sound career option on a careers page?

My answers: yes to the first, no to the second.

There’s enough trouble trying to get rid of this nonsense without it being presented as something someone might aspire to.

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Curiouser and curiouser (history of science & research topics) Grant Jacobs Feb 18


History of science is great stuff. There’s endless stories and I’ll introduce you to some excellent reading soon.

I paused for thought today, just a little, over how these popular accounts might be taken to represent all or most of the science of that time.

Astronomer Zhang Heng's water-driven earthquake detection/warning device (CE 132). (Source: Wikimedia Commons.)

Astronomer Zhang Heng's water-driven earthquake detection/warning device (CE 132). (Source: Wikimedia Commons.)

There’s a selection bias going on, of course.

The quirkier and more intriguing a story, the more likely a writer is to choose it. So we read the stranger stories of the past, not the routine – or at least the stranger from today’s viewpoint.

Crime writers, too. They’re more likely to pick the odd, the clever than the ordinarily brutal. (True?) This must, surely, also be true for those who write about the science associated with crime.

The same might be said for research projects.

I can recall–a number of years ago now–hearing a remark from an excellent technician. I forget exactly what was said, but it was a cheerful admonishment to effect that scientists were drawing conclusions from (early) ‘gene array’ studies based mainly on extrapolating from the exceptional cases, rather than looking to the commonplace.

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On learning the sounds of a new (spoken) language Grant Jacobs Feb 17


Infants learn languages so easily. In particular, they are able to distinguish the important sounds in a language.

Below are two videos of lectures given by Professor Patricia Kuhl (University of Washington) exploring how infants learn language.

The first first, the shorter of the two, is a TEDx presentation; the latter is a longer exposition given at the University of Washington. Both are aimed at a general audience.

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Backstage at the Diamond Light Source Grant Jacobs Feb 13

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Backstage Science are going behind several of the more prominent of England’s research facilities, giving an informal glimpse of what’s going on in there. It’s a nice concept, to try show what’s inside some of the larger facilities that most people would never get to see.

synchrotron-wikipediaIn the second video they have produced in the series thus far they visit The Diamond Light Source, the UK’s national synchrotron facility.

Simplistically put, synchrotrons accelerate particles to very high speeds to create very powerful beams at a chosen wavelength of ‘light’.

One use of synchrotrons are to work out the structure of a protein, but for now it’s enough to look at the machine itself. They’re pretty impressive!

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Darwin Day e-card – but I prefer a tree Grant Jacobs Feb 12

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The American Humanist Society is offering Darwin Day e-cards that you can email to friends. (Hat-tip: @StacyCBaker).

It’s fun idea, but one uses that darn linear iconography again:


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Of use of the active voice by scientists Grant Jacobs Feb 11


Immediately before the ScienceOnline2001 meeting, well-known science writer Carl Zimmer wrote a piece on his blog titled Death to Obfuscation! In it he wrote,

[…] Scientists have a fierce passion for the passive voice. I suspect it has to do with the abject humility that they claim as a virtue of their profession. No one has the temerity to actually write, ‘We discovered X.’ Instead, ‘X was discovered.’

I agreed with the sound advice the article offered but I wondered a little about the claims about what scientists do and don’t.

So let me channel the spirit of this tweet from Tom Levenstein (retweeted via Gloria Lloyd and others):

Be as critical and curious about craft of writing as you would be about science.

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