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I had of course heard of quicksand, but via a tweet today I learned that there is also such a thing as “quick clay”. Thank you Twitter!

As far as I can make out quickclay is unique in the sense that it is only found in those regions of the northern hemisphere that were glaciated during the last ice age (Pleistocene). The clay was deposited in the sea (as marine clay), but when the land mass later rose (due to post-glacial rebound), the clay was exposed, and formed the soil mass for new vegetation. The rainwater in these northern countries was quite aggressive to these clays, and the salt water in the pores was replaced by fresh water so that the ionic 'glue' of the clay was weakened, making the clay unstable. (Because of the way “flat” sheets of clay minerals stack in sea water and freshwater, marine clay contains relative large pores contrary to clay formed in fresh water, where the flat sheets lay flatter against each other). Quickclay deposits are rarely located directly at the ground surface, but are typically covered by a normal layer of topsoil, so that you may not discover that it is there until it is too late. While the topsoil can absorb most normal stresses, such as normal rainfall or a modest earth tremor, a shock that exceeds the capacity of the topsoil layer — such as an earthquake, or an abnormal rainfall which leaves the topsoil fully saturated so that additional water has nowhere to run off except into the clay — can disturb the clay and initiate liquefaction (excessive pore-water released), finally giving way to massive landslides (also known as quick clay slides).

In Canada quickclay is also known as Leda clay or Champlain Sea clay. In Canada alone, it has been associated with more than 250 mapped landslides. Leda clay deposits are a legacy of the Champlain Sea that once stretched from Pembroke to Quebec City (a.o covering what is now Ottawa and Montreal). As to Norway parts of the centre of Trondheim is built on quickclay with 2500 people at a high risk of being hit by a catastrophic landslide. In Norway as a whole 60,000 people live on top of risky quickclay.

In Norwegian:

• http://nrk.no/vitenskap-og-teknologi/1.7997947

PS:
A reader has kindly drawn my attention to a fantastic video (with English commentary) about a quick clay landslide that on 29 April 1978 devastated large areas of the rural district of Rissa in mid-Norway. One person died whilst 13 farms; 2 homes; a cabin and a community centre were taken by the clay masses.

There are other maps than geological maps (what a surprise!) They all tell different stories. Let me show you a few.

Here is one showing the Sahel:


The Sahel is a climatic transition zone between the Desert in the North and the Savannas in the south. The Sahel covers parts of the territory of (from west to east) Senegal, southern Mauritania, Mali, Burkina Faso, southern Algeria, Niger, northern Nigeria, Chad, (North) Sudan, and Eritrea. The Arabic word sāḥil ساحل literally means "shore, coast", describing the appearance of the vegetation of the Sahel as a coastline delimiting the sand of the Sahara. Some years it gets sufficient rain to sustain the population (like the biblical 7 years of plenty). Other (bad) years it is hit by drought. 2011 and 2012 are among the bad ones. More funding is needed to avert a humanitarian disaster in Africa's Sahel region where up to 14 million people are suffering from food shortages, the international Red Cross said a few days ago.

The next map is a historical map:


The map shows the extent of the Mali Empire in the 14^th century. Oh yes, there were great cultures in Africa before the Europeans colonised the continent, and most of to-days political boundaries are drawn rather arbitrarily and seldom reflect “nation states”. I have actually seen and heard clues of what the Mali culture once was in Senegal and The Gambia - understandable when you see this map. If you compare it with the Sahel map you notice that all of this Mali empire was south of the Sahel.

Next a map of the areas where significant numbers of Tuareg live. After the collapse of the Kadhafi regime many of those fighting on his side have had to flee southwards. They are further aggravating the problems in the Sahel. This includes Tuaregs who returned from fighting for Kadhafi and have taken up a decades-old battle for control of the north of Mali. Fightings that since mid-January have sent over 20,000 refugees into neighbouring states. This means that Sahel aid workers must avoid no-go zones in the conflict between Tuaregs and the Malian army, and the resulting displacement of thousands more Tuaregs.


So finally a political map showing country boundaries, for what such African boundaries are worth.

• http://www.voanews.com/english/news/africa/UNICEF-Calls-for-Urgent-Funds-to-Help-Sahel-Food-Crisis-139020424.html
• http://www.terradaily.com/reports/Libya_fallout_fans_Sahel_hunger_pangs_as_crisis_looms_999.html
• http://www.africasia.com/services/news_africa/article.php?ID=CNG.bfde8ce317beaf7d920ce18fdf5d323f.51
• http://www.irinnews.org/report.aspx?reportid=94829
• http://www.terradaily.com/reports/More_aid_needed_to_divert_disaster_in_Sahel_Red_Cross_999.html

A tropical cyclone has hit the island of Madagascar, with winds of up to 195 km/h. The damage may be as bad as in 1994, when a cyclone killed 200 people and displaced 40,000. Madagascar, the world's fourth largest island, is prone to cyclones and tropical storms, especially in the rainy season between February and May.

On 14 February 2012 at 07:15 UTC (10:15 a.m. local time - Madagascar/3:15 a.m. EST), the MODIS instrument on NASA's Terra Satellite captured this visible image of Cyclone Giovanna almost directly in the center of the island of Madagascar.

• http://www.bbc.co.uk/news/world-africa-17025328
• http://www.google.com/hostednews/afp/article/ALeqM5jYak3T1KyLCKxDXLvD_IjON8qsRg?docId=CNG.107187bf1d9600ec3e3ca2c05d5be856.651
• http://www.digitaljournal.com/article/319619
• http://www.aljazeera.com/news/africa/2012/02/201221411847251989.html
• http://www.miamiherald.com/2012/02/14/2641203/cyclone-giovanna-kills-3-on-madagascar.html
• http://www.nasa.gov/mission_pages/hurricanes/archives/2012/h2012_Giovanna.html

See also my post Malagasy Cyclone Season

Mexicans struggle with the worst drought in Mexico in 80 years. Half of Mexico is affected by the lack of rain, which is threatening food production and employment in the agriculture sector. So, what to do? Rain dance -- or is there anything better? Cloud seeding maybe?

In October 2010 the Convention on Biodiversity under the United Nations Environment Programme adopted a resolution which placed a moratorium on geoengineering unless it can be proven that the method in question can be shown to not have an adverse effect on biodiversity. Cloud seeding is however not considered to be geoengineering. Cloud seeding involves the spraying of selected clouds with chemicals, usually silver iodide, either from aircraft or from the ground through the use of generators or rockets. This leads to the formation of ice crystals, which grow in size until they reach the necessary weight to fall in the form of rain. Silver iodide can cause possible residual injury to humans and mammals with intense or continued but not chronic exposure.

Of course I can understand that the population is desperate, but doubts do remain as to whether cloud seeding is truly effective - or safe (what are indeed the potential effects on the air, water and soil of the chemicals used?).

• http://ipsnews.net/news.asp?idnews=106678
• http://www.guatemala-times.com/technology/energy/2927-cloud-seeding-an-uncertain-solution-for-the-mexican-drought.html
• http://online.wsj.com/article/SB10001424052970203711104577201043392294110.html

On 18 October 1356 an earthquake occurred near Basel in Switzerland which may have had a Mw magnitude as strong as 7.1. It destroyed the town of Basel, decimated its inhabitants, and caused much destruction in a vast region extending into France and Germany. It is the strongest earthquake to have occurred in Central Europe in recorded history. Could it happen again?

Less than 50 km north of Basel we find the oldest nuclear power station in France, at the village of Fessenheim about a km from the border with Germany. It entered into service in 1977. The concrete containment vessels that surround the reactors at Fessenheim are just a fraction of the thickness of those at the Fukushima Daiichi plant in Japan, at least one of which was shown to have cracked in the disaster there. The stations twin reactors were built about 10 m below the dike of the canal that runs alongside the Rhine River — the water serves as the station’s coolant — but France’s national utility, which runs the plant, has declined to study the consequences of a break in the embankment. I fully understand that the French ask themselves “Faut-il fermer Fessenheim ?” (Should Fessenham be Closed?). The front-runner in this year’s presidential race, Hollande, has pledged to close the plant if he is elected in May. The present president, Sarcozy won’t !

I suppose that there is no need to tell that German local authorities, and many citizens nearby, want Fessenheim closed and are angry that they have no say in the matter, despite the fact that the station sits just 1.5 km from their border. Switzerland, 40 km further south also wants Fessenham closed.

Maybe I ought to add that since its opening in 1977 the station has had no significant accidents. Does that mean that it is safe? (The design requirements for Fessenheim did certainly not specify that it must resist an (unlikely?) earthquake of magnitude 7 nearby).



The Rhine Graben is a failed rift system of Oligocene age (35.4 million to 23.3 million years ago). It is in fact the finest example of a graben I have ever seen. It formed as a response to the evolution of the Alps to the south and remains more or (I would say rather) less active to the present day. Not that the faults are very active, but a fault always remains a weak zone in the crust, where you may expect earthquakes to occur.

• http://www.nytimes.com/2012/02/03/world/europe/wishing-upon-an-atom-in-a-tiny-french-village.html
• http://www.platts.com/RSSFeedDetailedNews/RSSFeed/ElectricPower/8610936
• http://www.bbc.co.uk/news/science-environment-14189013

In French:

• http://elysee.blog.lemonde.fr/2012/02/06/sarkozy-prevoit-de-se-rendre-a-fessenheim-jeudi-et-ne-fermera-pas-la-centrale/
• http://www.terraeco.net/Faut-il-fermer-Fessenheim,41826.html

In Danish:

• http://ing.dk/artikel/126479-frankrigs-aeldste-a-kraftvaerk-ligger-i-muligt-jordskaelvsomraade

Hat tip to Jón Frímann for reminding me of Greenland’s hot springs.

Hot springs in Greenland have no breaking news value. There are thousands of them, and they have been known ever since the first Scandinavians emigrated to Greenland about a thousand years ago. On the Island of Disko alone there are over 2000 hot springs. The most famous and one of the warmest of them all are however situated on the Uunartoq Island near the village of Alluitsup Paa (in my youth known as Sydprøven in Danish). Over the last 150 years it has been regularly studied by biologists, and over this period measurements at the bottom have constantly shown temperatures ranging from 40°C to 41.9°C, and there is no reason to believe that this temperature range has changed over the last thousand years. Compared with the around 800 hot springs in Iceland with an average water temperature of around 75°C this is not extremely hot - but more like warm, I would say. The difference lies in the volcanic activity in Iceland -- the Greenlandish hot springs are not related to any volcanic activity. Geothermal springs without any connections to volcanoes or hot magmas are however not at all unusual. The water issuing from a hot spring is heated by geothermal heat. In general, the temperature of rocks within the earth increases with depth. If water percolates deeply enough, it will be heated as it comes into contact with hotter rocks, The now warmer water will seek its way upwards through cracks and faults and, if still hot enough, emanate as a hot spring. The water from hot springs in non-volcanic areas is heated in this manner and such springs are known all over the world. Some authors make a distinction between hot springs with water above 37°C and warm springs with water below 37°C (normal human body temperature). There is however no universally accepted definition of a hot spring, so that a hot spring may just mean any spring with water temperatures above its surroundings. Probably the most general definition of a hot spring is that it has the same temperature all year round and is warmer than the location's average temperature.

There are ruins of a nunnery built near the hot springs on the Uunartoq Island after Greenland was Christianized, around 1000, the choice of construction site may have been related to the hot springs. The surface water is usually between 34 and 38 °C and thus well suited for bathing. That the water should contain radium and for that reason have healing properties is a myth however. Radium has never been found in the water, so if it makes you feel well it is rather because of its temperature. Gas bubbles of pure nitrogen are however rising from the bottom. The nitrogen feeds a.o. nitrogen fixating cyanobacteria, that form thick gelatinous microbial mats.

Before the second world war there were plans to utilize the hot water for various purposes, and they even started digging with the intention of building a public swimming bath, but the war made an end to that.



By the way the Greenlandic word uunartoq means something like “is warming”.

• http://www.greenland.com/en/about-greenland/natur-klima/varme-kilder.aspx

The Empty Quarter, or as it is called in Arabic, Rub' al Khali (الربع الخالي‎) is said to be the largest sand sea in the whole world. It encompasses most of the southern third of the Arabian Peninsula, including most of Saudi Arabia and areas of Oman, the United Arab Emirates, and Yemen, and covers some 650,000 km2. It holds about half as much sand as the Sahara Desert.



The desert is 1000 km long, and 500 km wide. Its surface elevation varies from 800 m in the southwest to around sea level in the northeast. The terrain is covered with sand dunes with heights of up to 250 m, interspersed with gravel and gypsum plains. As seen in above satellite image the sand is a reddish-orange color due to the presence of feldspar.

For thousands of years this territory has resisted settlement as one of the Earth's hottest, driest, and most unyielding environments - hence the name "quarter of emptiness". However oil of excellent quality has been found there and is exploited. The al-Ghawar oil field is one of the world's largest.

Dust from The Empty quarter regularly give rise to dust storms also to neighbour regions. The NASA satellite image below shows a dust storm that swept over the Arabian Peninsula in early February 2012. The image was captured on 2 February 2012. This dust storm follows a familiar pattern for this region, with especially thick dust occurring in the southwest. Toward the northeast, the dust thins enough to show the Persian Gulf, Qatar, and Bahrain.

• http://earthobservatory.nasa.gov/IOTD/view.php?id=9054
• http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=77070
• http://ngm.nationalgeographic.com/ngm/0502/feature1/index.html
• http://www.infoplease.com/ce6/world/A0842602.html#ixzz1lKqaYr1o

Climate change effects the extent of Arctic sea ice, which again effects the climate. In my cartoon below I have shown two ways in which the ice cover effects the temperature.



The albedo effect: Albedo is the fraction of solar energy (shortwave radiation) reflected from the Earth back into space. It is a measure of the reflectivity of the earth's surface. Ice, especially with snow on top of it, has a high albedo: most sunlight hitting the surface bounces back towards space. Water is much more absorbent and less reflective. So, if there is a lot of water, more solar radiation is absorbed by the ocean than when snow or ice dominates.

The lid effect: Ice cover prevents release into the atmosphere of heat stored in the ocean.

Such effects make Arctic sea ice an important component in the global climate system.

A study recently published in the scientific journal Tellus A shows that the probability of cold winters with much snow in Central Europe rises when the Arctic is covered by less sea ice in summer. A shrinking summertime sea ice cover changes the air pressure zones in the Arctic atmosphere and impacts the European winter weather.

Retreat of the light ice surface reveals the darker ocean, causing it to warm up more in summer from the solar radiation (ice-albedo feedback). The diminished ice cover can no longer prevent the heat stored in the ocean being released into the atmosphere (lid effect). As a result of the decreased sea ice cover the air is warmed more greatly than it used to be particularly in autumn and winter because during this period the ocean is warmer than the atmosphere. The warming of the air near to the ground leads to rising movements and the atmosphere becomes less stable. Winds are driven by air pressure difference between the Arctic and mid-latitudes: the so-called Arctic oscillation with the Azores highs and Iceland lows. If this difference is high, a strong westerly wind will result which in winter carries warm and humid Atlantic air masses right down to Europe (cf. the severe January storms we had in North Western Europe last month (January 2012) - January on average in fact being the most stormy in this region). If the wind does not come, cold Arctic air can penetrate down through to Europe, as was the case in the winters of 2009/2010 and 2010/2011. Model calculations show that the air pressure difference with decreased sea ice cover in the Arctic summer is weakened in the following winter, enabling Arctic cold to push down to mid-latitudes.

It must be pointed out that other factors of course also play a role. The sea ice-atmosphere relationship suggests however a potential for use in operational Northern Hemisphere seasonal forecasts.

Reference:
Jaiser et al.
Impact of sea ice cover changes on the Northern Hemisphere atmospheric winter circulation
Tellus A 2012, 64, 11595
doi:10.3402/tellusa.v64i0.11595
(NB: published under the terms of the Creative Commons Attribution-Noncommercial 3.0 Unported License -- and thus not behind a pay-wall).

• http://www.tellusa.net/index.php/tellusa/article/view/11595
• http://www.sciencedaily.com/releases/2012/02/120201105126.htm
• http://www.physorg.com/news/2012-02-summer-arctic-sea-ice-winter.html
• http://www.constantinealexander.net/2012/02/new-study-shows-correlation-between-summer-arctic-sea-ice-cover-and-winter-weather-in-central-europe.html

Have you seen the doctor lately. Here is one that helps keep South African Cape Town healthy - "die Kaapse dokter" in English known as "The Cape Doctor“. The Cape Doctor is the local name for a strong south-eastern wind – also known as South-Easter - that blows around Cape Town. It is said to clear all pollution (dispersing brown haze, allergens, pollutants and irritants) in the city and across the Cape Flats, offering an amazing clear sky and view of the City and its Table Mountain. Last week it also helped extinguish a fire in the Tygerberg Nature Reserve in Plattekloof. Some winds seem to have a better reputation than e.g. the Californian Santa Ana winds - that by the way aggravate fire danger.

The wind was named "die Kaapse dokter" by early settlers. it occurs regularly between October and March (the South African summer) and is not always benign. Cape winds have been responsible for 484 shipwrecks and thousands of deaths in Table bay and on the shore of the Cape peninsula over the last 500 years.



The South-Easter/”Cape Doctor“ originates from the South Atlantic High pressure system, which moves further southwards in summer as the westerlies retreat polewards. The South Atlantic High then ridges south of the country and joins up with the South Indian High pressure system often forming a band of high pressure to the south of the country during summer. Air flows anti-clockwise around a high pressure and clockwise around a low pressure in the southern hemisphere, so the resultant wind over the Western Cape in summer is mainly from the south east.

• http://www.1stweather.com/regional/education/southeaster.shtml
• http://www.news24.com/SouthAfrica/News/Cape-Doctor-helps-Cape-Town-firefighters-20120125
• http://www.capetownmagazine.com/weather-cape-town/Cape-Towns-Cape-Doctor/160_22_17572
• http://www.qi.com/talk/viewtopic.php?t=2898&start=0&sid=b694d932c18e440af575279acc4e4672
• http://www.zigzag.co.za/news/enviro/8433/You-should-have-been-here-an-hour-ago---The-Cape-Doctor,-Western-Cape---%5B-your-world-in-a-photo-%5D