2009-04-20 | by Chris | Full Article | Comments (5)

Attention geologists and geobloggers alike: mark your calenders for Saturday, May the 2nd for the first ever Geobloggers in the Pub in London. Come along for an afternoon of drinking and a live podClast recording. Here are the details you’ll need:

Time: 2pm onwards

Date: Saturday the 2nd of May 2009

Place: Cittie Of Yorke Tavern, 22 High Holborn, Camden, London, WC1V 6BN, United Kingdom (map) – it’s a short walk from the Chancery Lane tube station, and it looks like this:

In order to find us, I’ll place a piece of A4 on the table which will look like this:

Hopefully see some of you lot there.

2009-04-20 | by Chris | Comments (8)

2009-04-09 | by Chris | Full Article | Comments (1)

The medieval city of L’Aquila in Central Italy suffered a magnitude 6.3 earthquake this morning at 0132 GMT. Below is the shake map of this quake from the USGS. Full details can be found at the USGS.

Earthquakes in Italy are not unusual. The collision of the African tectonic plate with the European portion of the Eurasian plate cause these seismic events just as in any other tectonic collision. What IS unusual about this particular event, however, is the strength of the quake. Below is a map of all earthquakes in this area between 1973 and today from the USGS.

So since 1973, there have been 11 earthquakes in the Italy/Northern Africa region of magnitude 6 and above (0.5%), vs 2,234 earthquakes between M4 and M5.9. This is also expected, as smaller earthquakes are simply more common than large ones, but there’s a stark contrast here as all of the strongest quakes are extremely shallow (<33 Km in depth) while weaker quakes vary across the entire lithosphere/upper mantle (due to the nature of this collision). As a contrast, here’s the same segmented data from New Zealand:

Earthquakes in New Zealand >M6 (left) vs M4-M5.9 (right)

That’s 46 earthquakes of M6 or greater (1.25%), and 3660 quakes between M4 and M5.9. You’ll notice there’s a spread of depths with both quake groups in the New Zealand case, due to the subduction-related interactions of the Pacific and Australian plates (with a patch of ≥M6, 300-500 Km, purple, earthquakes at the start of the Kermadec arc, a classic case of back arc volcanism).

If you’re interested in the human side of this story, the BBC has an article about the 27+ deaths and building damage which includes video.

2009-04-06 | by Chris | Comments (0)

As many of you may know, I’ve been in the UK for a couple of months, and I’ve got a couple more to go before jetting off to Europe in June and California in July.

On the first weekend of May I’ll be stomping around the mighty city of London and in between catching up with the 7 million kiwis who live there, I’d like to initiate the first Geobloggers in the Pub (calling it “Geologists in the Pub” would have set off my redundancy meter – but either will do). Before announcing official times and a location, I’d like to just get a show of hands from geologists or geo-interested persons who’d be willing to sit around a table in the mid afternoon in a pub in central-ish London on Saturday, May the 2nd.

Since it’ll be a podclasting weekend, I’m intending on doing a recording with whoevers there too, getting opinions on whatever geonews is around for 20-40 minutes. That’ll make it the first “live” podclast.

So, who’s up for drinks and some light conversation?

2009-03-25 | by Chris | Comments (7)

2009-03-23 | by Chris | Full Article | Comments (6)

The geoblogosphere is fantastic. We tweet (a lot now), we have carnivals and we even podcast once a fortnight. One thing we don’t do, though, is pool our combined centuries worth of geological knowledge in unified, constructive ways. At least not all that often.

I would like to make this post a call to arms of sorts to all geobloggers and internet-savvy geologists out there to help with something. This particular page, Wikipedia’s entry on the mantle, is an absolute shambles. Not only are things like the Mohorovičić discontinuity only mentioned in passing without much description:

The top of the mantle is defined by a sudden increase in seismic velocity, which was first noted by Andrija Mohorovičić in 1909; this boundary is now referred to as the “Moho.”

(The page on the Moho is equally as vauge), but the figures, links and some of the references and suggestions in this page are simply stupid. Look at this bit of the extremely brief section on temperature:

Modern observations suggest that the mantle is cold.[15][16][17][18][19]
The mantle of Mars is also cold.[20]
This has very serious implications for those who believe the mantle is convecting hot fluid.

That has a very serious whiff of the EEdiots about it. Especially considering that every single reference given about the “cold mantle” is either in regards to an underlying section of the equatorial Atlantic MOR being colder than expected, or other areas of other MORs or spreading regions being cooler than expected (for the record, references 16 and 17 are the same). Not a single one of those references suggests the mantle is cold. The reason being that the mantle isn’t “cold” (whatever that means anyway, cold compared to what? Very unscientific). Any layperson reading this page would, however, be left with the impression that there’s serious debate regarding whether the mantle can flow at all.

I hereby kindly request that anyone out there with sufficient expertise in the mantle or associated sciences to please help in righting this travesty. I’m not asking for this to be done today, but over the next year we should endevour to pretty much rewrite this entire Wikipedia entry (lest the EEdiots take it upon themselves to do it for us and misinform the public even further). Wikipedia is fickle, however, and the formatting can be difficult to master, so getting a grasp on it now would be advantageous if you intend to contribute.

I’ll be doing some of my own research and clean-ups, but it’d be great if other concerned parties could help out too. After all, we blog about our science because we want to inform the layperson about how cool it is and to advance public awareness. Ensuring the go-to website for basic scientific facts is accurate can only help our cause.

2009-03-20 | by Chris | Comments (9)

Callan at NOVA Geoblog has a new meme going:

What are ten things that every geology major ought to know about? The only restriction is you’re not allowed to list anything that has already been listed by a previous geoblogger. You don’t have to list everything, just ten important things

Mel at Ripples in the Sand has added to the list (both can be seen at the bottom of this post) and now it’s my turn. Embarrassingly I know nothing of “Pedogenesis” or “How aquifers work” as listed by Mel, but this is all about brushing up, isn’t it? : )

Here’s my list of 10 things every geology major should know:

1. The difference between absolute and relative radiometric dating.
2. Uranium-lead dating and how each element on the uranium 238 decay chain interacts differently with the environment.
3. The difference between a continent and a tectonic plate.
4. The properties of felsic, intermediate and mafic lava types.
5. How and why the melting temperature of a rock changes depending on the the concentration of volatiles therein.
6. What an ophiolite is and the significance of very old ophiolites.
7. The structure of the deep Earth (the upper and lower mantle including the MoHo and other zones)
8. The biological explanation for the formation of banded iron formations.
9. The insignificant difference between a volcanic sill and a volcanic dike.
10. How to spot changing environments in a stratigraphic column.

I could go on, but those seem pretty important. Below are Callan and Mel’s lists

Callan’s list:

1. The relationship between cooling rate and crystal size in igneous rocks.
2. The fact that rocks can flow, given sufficient temperature and pressure [and low strain rate, for the purists out there].
3. The idea that sedimentary rocks reflect specific depositional settings. By studying modern depositional settings and the sediments they contain, we can interpret ancient sedimentary rocks in light of the conditions under which they accumulated.
4. The fact that the chemical stability of molecular configurations (minerals) changes with different temperatures and pressures (metamorphism).
5. Large Igneous Provinces, and their potential role in tectonics and expressing mantle plumes.
6. Elastic rebound theory for the origin of earthquakes.
7. The notion of partial melting, and its relationship to Bowen’s Reaction Series.
8. An understanding of the carbon cycle, and an understanding of the atmospheric physics that facilitate global warming.
9. The role that rivers play in shaping the landscape: nickpoints, terraces, quarrying, abrasion, drilling of potholes, etc.
10. The Earth is 4.6 billion years old, which is extremely old in comparison to human life — and the reasons we think it’s so old [Pb isotopes, etc.].

Mel’s list:

1. Evolution.
2. Evidence for plate tectonics.
3. That fossils (and trace fossils) can provide more information about the rocks they reside in – depositional environment, chronology and correlation, water temperature, stratigraphic up, relative rate of deposition, water depth, etc.
4. And vice versa, the rocks can tell you a lot about the fossils that are contained within them – geography, taphonomy, chronology and correlation, etc.
5. The relationship between sediment production –> sediment transport –> sediment deposition.
6. How to identify minerals.
7. Differentiation and fractionation and how they apply to the planet, the solar system, and isotopes.
8. How aquifers work (or don’t work if we drain them too quickly).
9. Where our energy supply comes from. All facets from petroleum products, to solar radiation, to conductive metals extraction, etc. (These are also useful for seeking gainful employment as a geologist.)
10. Pedogenesis. How it takes thousands of years of chemical reactions and transport to generate the soils we use for agriculture. (And how we should be taking better care of them.)

2009-03-16 | by Chris | Comments (7)

2009-03-12 | by Chris | Full Article | Comments (2)

2009-03-06 | by Chris | Full Article | Comments (3)