What exactly happened, and actually still happens because aftershocks may take up to a week, roughly known: south moved to a fragment of the mighty Himalayan fault stretching along the highest mountains in the world. Area under the shift is approximately 150-200 km and a width of 50-60 km. On this particular block of rock that split second he lost his balance and remains unstable, is Kathmandu – Nepal’s capital millionth, one of the most densely populated cities on the globe where every square kilometer population of over 20 thousand. people (on average five times more than in Warsaw). This is the result of the first findings, which made Roger Bilhah, professor of seismology at the University of Colorado, one of the best experts in the Himalayan tectonic puzzle, which for three decades conducting research in Nepal, India and Tibet.
Earthquakes in the Himalayas there every day. However, most of them are too weak to be felt man. On average, once a decade shocks occur magnitude 6, which may already cause slight damage. In contrast, every few years, there is a shock with a power of 7 degrees or more. Such disasters have been enormous destructive force. Can cause enormous human and material losses. The one that struck Saturday in Nepal, was magnitude 7.8 on the Richter scale. Counting only the victims and the loss continues.
Previous such a disaster in the Himalayas took place in October 2005. In Kashmir. According to the data of Pakistan that killed more than 70 thousand. humans. The strength of that shock was 7.6 degrees. Therefore, it was not very strong. He was not very extensive – a fragment of the fault had moved only 40 km long. Pech was, that this block was under the densely inhabited regions, and the shock was shallow, which usually means large scale damage.
The above-mentioned perpetrator of all disasters in this part of the globe, which is a step Himalayan, pulls the length of 2500 km from northern Pakistan along the border between India and China, Nepal, Bhutan on the north-eastern states of India. This is one of the major tectonic boundaries on the planet. Colliding continental plates are two of the lithosphere – Indian and Eurasian south from the north. Both have similar density and no I do not want to plunge into the depths of the planet. For this reason – he says Bilhah – the region could be a source of earthquakes tens of times more powerful than the one that was the cause of Saturday’s tragedy. Such megawstrząsy happen, according to the researcher, an average of once every thousand years. Bilhah warns that within the expected disaster can be found densely populated areas of the valley of the Ganges and many cities inhabited by tens of millions of people. If the strike element in one of them, the death toll could reach hundreds of thousands.
When and where this area can be megawstrząs? is not known. In the last two years, the Himalayan region only a few times shuddered from a very severe shock. The largest recorded in 1950. In the province of Assam in the east of India. Magnitude was 8,5-8,7. Fortunately occurred in sparsely populated mountainous terrain and did not cause major damage.
A much more tragic was the shock of magnitude 8.1 degree, which in 1934. Destroyed around Kathmandu. 15 thousand were killed. humans. Note that the same city was destroyed by an earthquake as strong a hundred years earlier. – But these few disasters only a small part of this energy, which in the last two centuries gathered in certain parts of the Himalayan fault – emphasizes Bilhah. It is estimated that the power of 8,5-8,7 shock, and so from a few to tens of times more powerful than a Saturday, it’s a matter of time. But come to him for a year or 30 years from now, we can not say today.
Why did the earth’s crust along the Himalayas accumulates so much destructive power? India, traveling north to the speed of 4 cm per year, particularly hard breaking through Tibet. If he had not, they would be somewhere around Mongolia. Instead slope and along the fault line slip into a powerful Himalayan Tibetan Upland. But not without resistance. Movement of the rock mass is held jumps separated periods of forced interruptions. It is these spikes are a source of earthquakes, and the longer the interval between them – the worse.
Same Himalayas are also one of the consequences of the collision of India and Tibet. The resulting stacking rocks therebetween. Squeezed like a vise, the two plates of the lithosphere, increase at a rapid pace. Therefore, they are the highest on Earth. They argue, but at the same time too narrow. Bilhah using GPS transmitters calculated that attacking India and Tibet resisted entering them closer to each other at a rate of about 2 cm per year. At the expense of Nepal.
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