Sunday, 27 February 2011

10 Things You Didn't know about earthquakes - Part 1

Notes taken from the Iain Stewart video seen in my upper sixth classes this week:

Earthquakes are among the deadliest forces known to man, capable of releasing vast amounts of energy over a short period of time, crumbling buildings and turning solid ground into a mushy liquid that swallows houses whole. For the exam this summer you need toe able to comment on a range of earthquake case studies how we have approached management and how close we are to predicting the worst of these disasters.

This video took you through ten lesser known facts about earthquakes, mentioned some useful anecdotal evidence you can use in your essays and covered the surprising ways in which we have learned about this natural hazard.

1) Greece - how earthquakes affected our earliest civilizations

Ancient Greece is widely regarded as the birthplace of modern civilization, yet it sits upon the most earthquake prone region in Europe. Although today it is still littered with the remains of Classical Greece, many thousands more buildings have been lost either through natural weathering and decay or removed by antiquities hunters in the 18th century. By far the largest number have been lost to earthquakes, many of the most magnificent temples have been destroyed including the Temple of Apollo at Corinth, and the frequent seismicity led Aristotle o form the earliest "rational theory"on earthquakes (By rational we mean not based on the God Poseidon who liked to cause carnage and ruin). Aristotle likened the rumblings of the earth to the rumblings of the human stomach, and said earthquakes were caused by subterranean winds, much like trapped gas!

2) San Fransisco 1906 - the Birth of seismology

This was the worst earthquake in American history, a magnitude 7.9 struck, lasting 45 seconds, enough to nearly flatten most of American Boom Town built on the Gold industry (which is a by product of tectonic activity and rivers - the concentration of rare earth materials). Out of a city of 400 000 inhabitants, 6000 were dead and 200 000 homeless, fires from ruptured gas mains raged for three days.

This earthquake had significant impacts on shaping America as we see it today, the rebuilding effort saw the diversion of trade and population from San Fransisco to Los Angeles, which is now the larger city, it was the first natural disaster in America to be both photographed and filmed and led to significant further study of the topic. San Fransisco was due to hold the Panama-Pacific International Exposition - a significant draw for future industry and investors, and as such the move to rebuild was rushed. By far the worst affected area in the 1989 quake was the Interstate 880, a dual tier motorway which collapsed killing 42 people.
The problem following the breach of the new building codes, was that it took until the 1950's for buildings rebuilt after the quake to reach the quality demanded by 1906 building codes. This remains a significant problem and it is estimated that a large earthquake would have a significant impact on many of the buildings from this era, and potentially cause many thousands of deaths.

One positive outcome of this was that Henry Fielding Reid, an American Geophysicist, formed a new scientific theory on earthquakes, this is the theory of elastic rebound and strain, and was the first to set out how rocks are strained along fault lines to a point at which they snap, releasing energy which is the cause of earthquakes. This theory remains one of the most important developments in tectonics and is studied world wide.

3) Paranoid Eureka Moments - Seismology and Nuclear Testing

During the height of the cold war and the nuclear arms race, America developed the means to remotely spy on Russian test sites for nuclear weapons. As the two nations developed nuclear capability, America's desire to know how large the bombs were led them to place over 120 seismometers worldwide to record the seismic shock traces left by weapons testing.

Novaya Zemlya was the designated Russian test site, in total 224 Nuclear detonations took place here, the largest of which registered as a 6.97 on the Richter scale and generated an 80 million tonne avalanche which blocked several streams and created a lake 2km long.
In total the tests at Novaya Zemyla held the explosive energy equivalent to 265 megatons of TNT.For comparison, all explosives used in the Second World War, including the detonations of two U.S. nuclear bombs, amounted to only two megatons.

The unexpected side effect of this remote spying, was that not only were all the Russian tests recorded, but the location of earthquake epicentres could also be located and plotted, and for the first time, earthquake foci were observed to follow straight lines, or late boundaries as we know them today. It is worth remembering that although Wegner proposed Continental Drift in 1908, we still lacked an understanding of the potential mechanism for movement, and this was still regarded as a fairly crazy theory until the early 60's.
The final thing the nuclear seismographs showed, was that the plates were moving in specific directions. One of the final pieces of evidence needed for continental drift to be accepted and linked to hazard management.

4) Why loose rock is dangerous.

The Shaanxi earthquake was the deadliest quake in history, for one reason - the rock type. Called Loess it is loose windblown sediment, common in China and a vital proxy for understanding climate change (dont worry thats in the next module). Wen shaken, it collapses, and in this region, it had been used to carve out cave dwellings for centuries. Over a million people died, and the damage spread as the L waves amplified through the soft sediments causing significant ground roll and destruction. It is worth noting that there are many other areas built on soft rock that have not experienced an earthquake in the recent past (ie since we have developed the region/urbanised).

5) Mexico's Tallest tower

Mexico City is built on the dried up bed of an old lake, first drained by Spanish Settlers. As such is it notoriously unstable, with foundations of loose, unconsolidated sediment, on a subduction zone, hence prone to large earthquakes, and located Right next door to the monstrous Popocatepetl. Yet, completed in 2003, the Torre Mayor is Mexico's tallest building, a towering 200m and 55 storeys high, it is one of the most high tech buildings in the word. A series of interlocking diamonds with colossal shock absorbers at the overlaps holds the structure in place, and should counteract the motion of the ground during an earthquake.

It is built on one of the most unstable parts of the city, the ground here liquefied in the 1985 quake,with the soft sediments amplified the waves and turned much of the ground to liquid. The video referenced in the documentary was the Niigita Earthquake of 1964, where liquefaction was first filmed

It has since been experienced at many locations world wide, notably last year in Christchurch, and this February as well, but there will be a separate post on this coming soon. So, it is possible to earthquake proof buildings, this is by no means the only example, the Taipei 101 tower is another, and there are many buildings in LA with shock absorbers or counteraction weights. It is also possible to retrofit older buildings to make them earthquake proof, however, the recent quake in Christchurch has demonstrated the fact that large aftershocks on already weakened buildings, even if they are retrofitted, can only withstand a certain amount of shaking.


Just a quick post to start with, there is a longer one on the way!!

The two class case studies blogs are up and running, and the student blogs are quite worryingly (only  for my ego's sake) looking better than mine at the moment, so I will have to up the standard of my blogging!

Firstly, a quick thank you to all of you who emailed to ask about my eyes, much appreciated, I now have perfect vision without lenses or glasses so it will be harder than ever to fall asleep at the back of my classroom!

Secondly - the tragic earthquake in Christchurch has been a shocking development from last Septembers earthquake, and goes to show that even in a developed country, well used to earthquakes and with all planning possible in place, earthquakes are one of the most devastating natural events. The next blog post will look at the science behind this quake and why it has been so deadly, we will also be discussing it in class tomorrow so if you have any questions, let me know then, and I will try to create a useful case study on this latest event.

Thirdly - what is going on in Iceland? For those of you coming on the trip, or following the Iceland Met website, the last few days have seen a swarm of rather larger than average earthquakes. No reason to worry, but who can work out what is going on?

here is an image from today:

Answers on a blog comment underneath, its quite interesting (yes I do know the answer)

Thursday, 10 February 2011

Encounters At The End Of The World

This DVD is now in stock in the LRC, it is on the geography display shelf, check it out! (Literally!)

Tuesday, 8 February 2011

How Earth Made Us - Notes from the episode on Energy

Type up of the notes taken from the video watched in class last week and some extra pictures and background!

The video started by discussing how before the 16th century, the UK was covered in deciduous broad leafed forest, which is our climatic climax vegetation. Whilst the balance between usage and production through growth of new biomass remained in balance, this was fine, but as we started to develop, and to require more fuel for cooking and heating, early industry and building, our forests were decimated, so that by the end of the 17th century, all but a few of our largest forests were gone. As the fuel supplies started to dwindle in the form of fuel wood, we were forced to seek alternatives, the first of which was coal. Readily available in the UK, close to the surface and easy to access in our northern coalfields, we started to mine the seams, following them underground to extract more of this "Stored Sunshine", as our demand for energy outstripped the rate at which photosynthesis could produce new material for us to burn.

This in turn, led to the development of the steam engine, first as a means to pump water out of ever deeper mine shafts to allow excess to deeper coal, but it was quickly adapted for motion, and became the steam engine as we know it today. Perhaps this is evidence for Boserups's early ideas on population, as our needs develop, we will develop the means to meet them?

Coal formed in most global deposits during the Carboniferous Period, between 360 and 300 million years ago in swamp environments when the worlds first early forests developed. The Lake Iain Stewart was diving in was in Oregon, and is called Clear Lake, but there are several other examples of forests that have been submerged in cold waters and preserved, the photo below is one from Kazakhstan called Lake Kaindy

The Carboniferous is so called due to the massive expansion in forest and plant growth, especially following the development of Bark bearing trees and the first growth of plants with Lignin, important, as the trees had bark that was particularly hard to degrade, there were bark to wood ratios of between 8:1 and 20:1 as opposed to modern day 1:4, lignin concentrations were higher in these early trees, meaning that the bark was toxic to most fungi and bacteria, so when the trees died, there were few organisms that could break it down. The other main reason as to why forest bloomed in this time period is because there was a significant fall in sea level which led to the development of massive lowland swamps, meaning a carboniferous scene may have looked lie the artists impression below:

The most significant long lasting effect of this period, was that this development of huge forests and trees, and the trapping of CO2 in swamps raised the level of oxygen in the atmosphere to as high as 35% (today it is 21%). This is one of the speculated reasons as to why later organisms (dinosaurs) could grow to such gigantic sizes due to the abundance of oxygen. The carboniferous ended with a significant ice age, but the forests remained buried in anoxic environments, and after subsequent layers of beds were laid down on top of them, they were compressed into coal.

So why is this important? This is where our excess CO2 production today comes from, we are now using up this coal resource, and releasing this carbon that was captured during the carboniferous back into our atmosphere. The fact that the UK during the early Carboniferous had vast swamps and deltas, and we developed extensive coal reserves, meant we were one of the first countries to develop a coal based economy, the driver behind our industrial revolutions early start.

So, why were we one of the first countries to develop our coal based industry? There is another country with even larger readily accessible coal reserves, which was technologically advanced at an early stage in history, but didn't keep pace with the UK. China's coal reserves are now one of the Climate Change camps most significant concerns.  The reason China has not exploited them until recently, is two fold. Firstly, being such a large country, their focus on meeting needs was running the empire, the second problem, is that China's coal fields are far inland, up the impassable Yellow River, filled with treacherous rapids (a product of the local geology) and a shallow dangerous river regime for large boats:

But, we have studied the Mississippi in the Rivers module, this river has been extensively managed for shipping since the mid 19th century, so why didn't China manage the smaller Yellow river? They didn't need to, China's main trade was via the sea, most of its large developing cities were on the coast, whereas America had to manage the Mississippi flooding to develop and to trade with the Interior, perhaps another one for the Population Optimists?

Onto Oil, when we ran out of coal, heavy, dirty and difficult to transport, we turned to its sister fossil fuel, Oil. Cleaner burning, more efficient, more mobile and with a wider range of applications, Oil was the natural preference to coal. The first city to see a boom in the oil trade was Naftalan in Azerbaijan. The location of the rather icky scene in the documentary where Iain takes a bath in some yummy crude oil. This is an old application for oil, its purported health benefits may seem comical now, but people have bathed in oil for a long time:

This picture from the 1930's is of the Naftalan treatment centre, which the Soviet Union invested heavily into to discover it holds any true benefits, the answer is possibly, it is a thermal treatment and has had some success treating arthritis and other muscular-skeletal disorders. The big question is, do you really fancy taking a bath in fossilised fish poo and plankton?? Like this guy:

To be honest, it doesn't appeal to me, but each to their own. Back to geography, is it really worth it? This is a photo of the Azeri oil fields, the level of contamination in the water is high and the scenery is blighted by the presence of hundreds of nodding donkeys:

The impact of this is that many streams an lakes around Baku are now biologically dead, and scenes like this one are not uncommon:

The location of major oil reserves across the world is not even, it is not even allied to those countries that have a high dependency on oil. The ease with which oil could be moved, meant it was the first fossil fuel that could be extracted and exported whilst maintaining a profit. The region that won the geological lottery of having been a shallow marine sea for most of the last few million years was of course the middle east, Saudi Arabia in particular has colossal oil reserves almost 22% of the worlds proven reserve.

We will be coming onto geopolitics in class soon if you haven't started it already, but the point in the video was that oil is found by looking for salt, not something you need to worry about unless you are taking geology as well, in which case, you need to understand why, but here is a picture of Iran's Salt River, fed by the Salt glacier that Iain walked over, with some spectacular salt formations in it;

To end, the development of "Oily Rocks" of the coast of Azerbaijan during the 1950's was the first offshore drilling platform, and is quite unusual, it was one of the first oil pipelines laid, it hosts a temporary population of up to 3000 people working in two week shifts, its own power stations and entertainment facility.

So, that's it for this post, it has been fairly lengthy, but understanding this difference in the location of oil and the location of oil consumers is key to most of this module. Keep reading the student posts on their blogs which can be followed through mine, and if anyone else has another blog to add it would of course be much appreciated, just email me!


Sunday, 6 February 2011

Encounters At The End Of The World

This is possibly one of my most favorite films ever (After Harry Potter and Lord of the Rings of course), it was original, interesting and insightful, with fantastic footage and some quirky characters. It is however a documentary, made by German Filmmaker Werner Herzog, it documents the life of people living in Antarctica, based in McMurdo, the sort of make shift Capitol of Antarctica.

The film follows the stories of a few different groups of scientists who are working on Antarctica, and a few of the other characters such as the Bus driver, the random collection of travelers and survival trainers. The scientists are some of the most respected in the field of Glaciology, such as Douglas MacAyeal, whose theories on ice sheet disintegration we will study when we get to Heinrich Events (see the wikipedia page for a sneak peak of our last module here).

The interviews are a fantastic mix of the truly bizarre, including the lady who can fold herself up into a suitcase, and the out rightly terrifying perspective on radical climate change and the break up of the ice sheets, and giant icebergs, and my personal favourite bit, the volcanologists studying Mt Erebus which is monitored using the CCTV cameras currently employed in high security prisons!

The film clearly has an underlying message about the fate of the world, otherwise it wouldn't be on my list of movies to review, but it is also a positive movie, the scenery is just stunning, the wildlife is incredible, and for me the noises of the glacier and diving under the ice sheet were pretty jaw dropping (yes students, I know I am a nerd). The only thing i really didn't like, was how developed McMurdo was, my vision of Antarctica had always been of a pristine, unspoiled wilderness, but I was very wrong, it is in fact a small town, filled with people for most of the year, although their work is important, it slightly spoilt my mental image of the wilderness, and it left me feeling slightly sad that even Antarctica, vast and hostile though it may be, has been encroached so much by people already.

So, why is this a good geography movie? Firstly, it is just awesome, Herzog has made a very unique and fascinating movie, secondly, I have always wanted to go to Antarctica, and this is a very different view of the continent than presented in other movies about it. Lastly, it does in fact link to our syllabus quite a lot. The studies taking place at Erebus are useful tools for learning how to predict other eruptions, the Ice Caps are one of the most important things for us to understand in terms of future and past climate change, and are our most complete and accurate record for paleoclimatology over the last 600 000 years. You wont learn much about these things just from the movie, but as a good lead in to our final module in the Upper Sixth, you cant beat it. So, the Library have ordered it, and it will be there soon, let me know what you think!

Thursday, 3 February 2011

The Awesome Awesomeness of Silica (AKA Volcanology 101)

Hello Everyone!

Exams are over and it is time to get back to the grindstone, just as well we are starting back on one of my favourite areas of study in Earth Sciences which is if course, volcanology. Thinking of volcanology and volcanologists summons up images of Pierce Brosnan in Dantes Peak (Essential geography viewing in terms of spot the errors - clue - you cant drive over lava flows!) and wild majestic peaks covered in snow, well, perhaps only if you are me, as you may have gathered i love volcanoes! (Be warned Icelandic Field trippers, ask me a question and I will talk for hours!).

In reality, understanding and appreciating this particular branch of science hinges on one thing, silica. It controls the nature of the explosion, the shape of the volcano and the produces/hazards, and itself is controlled by plate tectonics. Silica makes volcanoes sticky, explosive and violent, whereas a low silica diet produces runny, flat and effusive gassy volcanoes (they do not trap gas, it escapes easily therefore gas is a hazard).

Silica in its purest form forms quartz, a crystal you have probably seen plenty of times before

Why is silica so important? It traps gas, it melts at low temperatures, is the last thing to solidify out of the melt. Translated into geography talk, the low melting point means that at convergent boundaries, volcanoes above the subduction zone will always be more silicic for two reasons:

1) The sub ducting plate melts, and the lowest temperature forming minerals, melt at the lowest temperatures, this happens to be silica, so the pluton of melt that is released from the melting plate will be enriched in silica, it rises as soon as there is enough melt as it is hotter , and lighter than the surrounding semi- solid mantle.

2) as the pluton rises, it cools, loosing heat to its surroundings, what this means is that the higher temperature forming minerals form a solid mass as the melt cools past their crystallisation temperatures, and being solid they are heavier and sink to the bottom, thus leaving the remaining molten rock enriched in silica

This is why, the most destructive eruptions are always found on convergent margins, and the worst are found when magma rises through the full thickness of a mountain chain. Therefore we can easily identify that continent/ocean convergence zones are the most explosive.

This does not mean that they are the worst volcanoes for people, there are plenty of big acidic eruptions that don't affect us in any way, you need to remember that a risk only becomes a hazard when people are potentially affected, these are the ones such as Sarychev and Shiveluch on the Kamchatka Peninsula (My favourite choice for my next holiday location), Sarychev erupted last year and the images were captured in this spectacular video of the eruption column by satellites:

The Kamchatka Peninsular is sparsely populated, with few major cities and the worlds highest concentration of active volcanoes, most of which are explosive, and the notorious "Valley of Death" a region with a heavy concentration of fumaroles and minor forms of extrusive activity which leads to a near total absence of oxygen in the first metre above ground level, and high concentrations of Carbon Dioxide and Hydrogen Sulphide. Hence, although these are some nasty volcanoes, they pose little risk, and certainly none that cannot be managed by diverting flight paths away from the ash clouds.

That is not to say that our basaltic volcanoes are the most dangerous, indeed quite often they present a significant opportunity  for tourism and research, and can bring in many millions a year to an area, in fact Mt St Helens now brings in the vast majority of the Cowlitz and Skamania Countries $105 million per year, with over three million visitors to the National Park every year.

Some Basaltic volcanoes have claimed more lived and done more damage than their more explosive but less frequent sister eruptions. Basic volcanoes may be prettier, with bright glowing lava, but lava can travel for several tens of kilometers from the vent, release far more gas, which could be a more deadly hazard (ie Lake Nyos - Invisible and Odourless).

So, does the difference in impact come down to money? Well, at least in part yes, but there are significant other factors. Disasters that happen during rush hour, or the middle of the night tend to be more deadly, those that occur in cities will always have more of a demographic impact, those that occur in agricultural regions such as Armero will have a wider social implication as the food supply could be affected. Those that have the potential to affect the water supply, either through contamination by decay or pollution, will cause a widespread and possibly ongoing disaster. So in fact, hazards potentially could cause similar levels of destruction, however, the financial impact tends to be more significant in developed countries whereas the social impacts are more significant where money has not allowed hazard planning and mitigation strategies to develop.

The final element for discussion, is whether or not the primary or the secondary impacts are worse, and whether the relationship changes from MDC to LDC? Certainly secondary impacts are harder to address in LDC's. as the three basic necessities are harder to come by (food/shelter/water), and recovery is often slowed by the requirement for aid rather than the country having the financial means to recover independently.

This debate forms the basis for many of the A2 questions, there is no right or wrong, the marks come from discussion and debate around the issues, and the careful use of appropriate case studies. Case studies do not have to be in a lot of detail, hence the need for you two know two eruptions well and anecdotal evidence for a fair few more.

Finally, some of you have been asking about the background picture on my blog, it is in fact a giant natural smoke ring produced by Etna, one of the few volcanoes known to puff giant perfect circles like these:

Don't ask me how or why, it just does and it is fascinating, Stromboli has done it as well, there were a couple in Iceland last year, but they have always struck me as rather fabulous!

See you tomorrow