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Πέμπτη 30 Απριλίου 2015

How earthquake safety measures could have saved thousands of lives in Nepal

Poorly built houses were destroyed in the
Credit: Domenico/flickr, CC BY-SA
Earthquake engineers often say earthquakes don't kill people, collapsing buildings do. The tragic loss of life that followed the huge earthquake in Nepal on April 25 occurred despite the fact that the country is among the world's leaders in community-based efforts to reduce disaster risk. But poverty, corruption, and poor governance have all led to a failure to enforce building codes – as has a shortage of skilled engineers, planners and architects.

Sadly the country was on its way to deploying knowledge and skills to tackle its long-term vulnerability just as the ground shook.

So why aren't more buildings designed to withstand shaking – even extreme shaking.

To keep buildings standing, it is essential to have adequate building and planning codes, as well as proper training and certification for professionals such as engineers, architects, and planners. But having certification and codes on paper does not ensure implementation or compliance. Nepal does, after all, have some of these things. Laws and regulations must also be monitored and enforced. That is not easy in a country such as Nepal, which has isolated villages, a history of conflict and many governance difficulties.

Vast vulnerability


Financial as well as social resources are needed to set up earthquake resistant buildings. Governments at all levels need to be functioning and competent in order to engage with processes such as urban planning and earthquake-resistant construction. Citizens must trust and have the opportunity to work with their governments, including the law enforcement and judicial sectors.

It's not just about buildings. Many non-structural measures are needed to ensure survivability in earthquakes. Appliances such as televisions, microwaves, hot water boilers, and refrigerators (which do not always exist in Nepalese homes) must be securely fastened to the floors and the walls. Otherwise, they move and topple, killing as readily as building collapse. Even in affluent earthquake-prone locations such as New Zealand and California, we see shockingly low rates of households enacting these basic measures.

But Nepal is not New Zealand or California. It has been wracked by conflict and troubled by unstable governments, not to mention the governance issues caused by being sandwiched between China and India. It has long had high poverty and low formal education rates.

Despite recent improvements, Nepal still lags behind other countries when it comes to human development and it is still seen as highly corrupt. It also scores badly on child health and gender equality measurements.

When families struggle daily for enough food to keep their children healthy, they are not likely to spend time thinking about making their home earthquake resistant.

And when children are malnourished and stunted, they perform worse in school. That leads to long-term education inadequacies that prevent them from developing into adults with the skills to lobby for adequate and enforced building codes. What's more, when women lack the same opportunities as men, half the population is excluded from demanding and enacting good governance.

All these factors contribute to the country's vulnerability. All these factors have led to housing and infrastructure prone to collapse in an earthquake.

Rebuilding a nation


None of these things can be solved overnight. Tackling vulnerability is a long-term process, yet earthquakes strike and bring down buildings in seconds and minutes.

As the earthquake struck, Nepalese people were working hard to overcome these vulnerability conditions. My friends and colleagues from the country have taught me plenty about retrofitting buildings and constructing earthquake-resistant homes.

They travelled to communities with small shake tables, which are used to simulate earthquakes by shaking model houses or building components, showing the difference between an earthquake-resistant house and a non-earthquake resistant house. They made many schools safe. They taught school children and their parents about earthquake-safe behaviour.

These efforts saved hundreds of lives, if not more, during the recent tremors. With a few more decades, a mere instant in geological time, they could have made Nepal comparatively safe from earthquake disasters despite earthquakes. In that time, so many more buildings would have been retrofitted, we might have had adequate building code enforcement, and most importantly, an earthquake-educated and vulnerability-educated generation would have started to take power.

Nepal must now continue these efforts in order to avoid similar future devastation. We can be optimistic. Education is happening – for boys and girls. Women are increasingly being given equal opportunities as men. This means the Nepalese people are taking charge of their own health, their own environment, and their own sustainability. That is vulnerability reduction over the long-term.

Τετάρτη 29 Απριλίου 2015

USA: National Guard out in full force in Baltimore

Inhospitable climate fosters gold ore formation

The richest gold ore in Witwatersrand is found in thin layers rich in carbon,
plating fibres of ancient microbial life forms.
(Photo: James St. John / Wikimedia Commons)
The Witwatersrand Basin in South Africa holds the world's largest gold deposits across a 200-km long swathe. Individual ore deposits are spread out in thin layers over areas up to 10 by 10 km and contain more gold than any other gold deposit in the world. Some 40% of the precious metal that has been found up to the present day comes from this area, and hundreds of tons of gold deposits still lie beneath the earth. The manner in which these giant deposits formed is still debated among geologists. Christoph Heinrich, Professor of Mineral Resources at ETH and the University of Zurich, recently published a new explanation in the journal Nature Geoscience, trying to reconcile the contradictions of two previously published theories.

The prevailing 'placer gold' theory states that the gold at Witwatersrand was transported and concentrated through mechanical means as metallic particles in river sediment. Such a process has led to the gold-rich river gravels that gave rise to the Californian gold rush. Here, nuggets of placer gold have accumulated locally in river gravels in the foothills of the Sierra Nevada, where primary gold-quarz veins provide a nearby source of the nuggets.

But no sufficiently large source exists in the immediate sub-surface of the Witwatersrand Basin. This is one of the main arguments of proponents of the 'hydrothermal hypothesis', according to which gold, chemically dissolved in hot fluid, passed into the sediment layers half a billion years after their deposition. For this theory to work, a 10 km thick blanket of later sediments would be required in order to create the required pressure and temperature. However, the hydrothermal theory is contradicted by geological evidence that the gold concentration must have taken place during the formation of host sediments on the Earth's surface.

Rainwater rich in hydrogen sulphide


Heinrich believes the concentration of gold took place at the Earth's surface, indeed by flowing river water, but in chemically dissolved form. With such a process, the gold could be easily 'collected' from a much larger catchment area of weathered, slightly gold-bearing rocks. The resource geologist examined the possibility of this middle way, by calculating the chemical solubility of the precious metal in surface water under the prevailing atmospheric and climatic conditions.

Experimental data shows that the chemical transport of gold was indeed possible in the early stages of Earth evolution. The prerequisite was that the rainwater had to be at least occasionally very rich in hydrogen sulphide. Hydrogen sulphide binds itself in the weathered soil with widely distributed traces of gold to form aqueous gold sulphide complexes, which significantly increases the solubility of the gold. However, hydrogen sulphide in the atmosphere and sulphurous gold complexes in river water are stable only in the absence of free oxygen. "Quite inhospitable environmental conditions must have dominated, which was possible only three billion years ago during the Archean eon," says Heinrich. "It required an oxygen-free atmosphere that was temporarily very rich in hydrogen sulphide -- the smell of rotten eggs." In today's atmosphere, oxygen oxidises all hydrogen sulphide, thus destroying gold's sulphur complex in a short time, which is why gold is practically insoluble in today's river water.

Volcanoes and bacteria as important factors


In order to increase the sulphur concentration of rainwater sufficiently in the Archean eon, basaltic volcanism of gigantic proportions was required at the same time. Indeed, in other regions of South Africa there is evidence of giant basaltic eruptions overlapping with the period of the gold concentration.

A third factor required for the formation of gold deposits at Witwatersrand is a suitable location for concentrated precipitation of the gold. The richest deposits of gold ore in the basin are found in carbon-rich layers, often just millimetres to centimeters thick, but which stretch for many kilometres. These thin layers contain such high gold concentrations that mining tunnels scarcely a metre high some three kilometres below the Earth's surface are still worthwhile.

Hard and dangerous labour: The mines
provide no place to stand.
(Photo: Courtesy Prof. C. Heinrich)

The carbon probably stems from the growth of bacteria on the bottom of shallow lakes and it's here that the dissolved gold precipitated chemically, according to Heinrich's interpretation.

The nature of these life forms is not well known. "It's possible that these primitive organisms actively adsorbed the gold," Heinrich speculates. "But a simple chemical reduction of sulphur-complexed gold in water to elementary metal on an organic material is sufficient for a chemical 'gilding' of the bottom of the shallow lakes."

The gold deposits in the Witwatersrand, which are unique worldwide, could have thus been formed only during a certain period of the Earth's history: after the development of the first continental life forms in shallow lakes at least 3 billion years ago, but before the first emergence of free oxygen in the Earth's atmosphere approximately 2.5 billion years ago.


Δευτέρα 27 Απριλίου 2015

Hit by Avalanche in Everest Basecamp 25.04.2015

Harrowing videos of Mount Everest climbers running from an avalanche and watching as the injured were airlifted off the mountain began to emerge today from the aftermath of Nepal's 7.8 magnitude earthquake. 
The climbers described chaos as the avalanche headed for the base camps where many of Nepal's mountain climbing tourists, Sherpas, and guides were beginning their ascent of the mountain.  
Footage captured by a German climber shows the terrifying moments after the earthquake hit when a wall of snow and ice came barreling down the mountain.

Κυριακή 26 Απριλίου 2015

Search for avalanche survivors on Everest begins

Δημοσιεύτηκε στις 26 Απρ 2015
After the devastating Nepal earthquake touched off an avalanche, 17 climbers have been found dead at the Everest base camp. Pictures from Everest’s south side base camp show flattened tents and blocks of rock scattered around a site deep in snow. Carsten Lillelund Pedersen, Danish climber, was on Mount Everest when the avalanche hit. He filmed these pictures as a rescue effort got under way.Al Jazeera's Ali Mustafa explains.


Residents view Chile volcano damage

Δημοσιεύτηκε στις 26 Απρ 2015
Residents who live on the foothills of the Calbuco volcano return to assess the damage after it erupted without warning on April 22. Rough cut (no reporter narration).


Iranian General Discusses Possible Terror Attacks in Saudi Cities, Adds:...

Δημοσιεύτηκε στις 25 Απρ 2015
In a recent TV interview, Brigadier-General Ahmad Reza Pourdestan, Commander of the Iranian Ground Forces, said: "If Saudi cities were targeted by bombings and missiles, it would be difficult for the officials there to withstand this." He further said that in order to prevent a Sunni-Shiite union from materializing, "the first thing [the Americans] did was to plan and carry out the events of 9/11." Pourdestan was speaking on the Iranian Al-Alam TV channel on April 19, 2015.


Διαδηλωτές στη Βαλτιμόρη σπάσιμο αυτοκίνητα της αστυνομίας

Δημοσιεύτηκε στις 26 Απρ 2015
Διαδηλωτές αυτοκίνητα της αστυνομίας και καταστήματα επιτέθηκε κεντρική Βαλτιμόρη ανατολικές Ηνωμένες Πολιτείες, στο περιθώριο από τα μεγαλύτερα συστήματα συλλογής από το θάνατο του νεαρού άνδρα αφρικανικής καταγωγής, αφού τραυματίστηκε κατά τη σύλληψή του από την αστυνομία