Scientists: plate tectonics in Pakistan is moving like a caterpillar

January 16. Kohat plateau in north-western Pakistan is a special geological structure, which moves on the surface of another tectonic plate small, successive short steps — about the same as a caterpillar, say Indian and American geologists in a paper published in the journal Nature Geoscience.

Bilhem Roger (Roger Bilham) from the University of Colorado at Boulder (USA) and his colleagues believe that "tracked" the motion of the plateau was the cause of the mysterious earthquake May 20, 1992, the strength of which reached 6 points on the Richter scale. To date, this event is considered the most powerful earthquake for the time in which people live in the north-western boundaries of Pakistan.

The scientific team led Bilhema tried to find the reasons for this earthquake, the structure of tectonic plates in the region of the epicenter with special interferometric radar.

As noted in the article, the area of Kohat Plateau is interesting because in this region there are two major tectonic plates — the Eurasian and Indian. Eastern and northern boundaries between them are the entire length of the Himalayas and other mountain massifs, where the clash between the plates causes the rare but extremely powerful earthquake.

On the other hand, the western part of the impact zone is different "quiet" nature. This territory goes smoothly Indian plate beneath the Eurasian plate rocks coming through a layer of soft rock on which the slide of its mass.

Scientists have "gaps" this substrate using interferometric radar and found that there are several areas where they played harder than in other regions of the plateau of rock. Apparently, one of these points was the epicenter of the 1992 earthquake, as evidenced by the strong deformation of the substrate material itself and covering her Indian plate.

As explained Bilhem and his colleagues, and other volcanic ridges of solid rock on the surface of the substrate significantly slow down "flow" downstream rocks. As a result, the matter of Indian tectonic plate gradually accumulate in the lip, causing the pressure and stress at this point gradually increased. After some time the board has broken, which was the cause of the earthquake.

After this plateau continued to fall under the Eurasian plate without major obstacles. Scientists compare this way of movement of the cortex to the way a caterpillar crawling — it moves only one segment of the body and moves them one by one, from the head to the tail, resulting in an undulating motion characteristic.

The researchers suggest that "tracked" nature of the flow of rocks is the main cause of a small number of earthquakes in this part of Pakistan.

According to their calculations, the crash in 1992 is the exception rather than the laws — such events should occur no more frequently than once every 600 years. Following an earthquake is likely to occur in the southern part of the plateau in the mountains Surgar adjacent to Kohat Plateau. The maximum force of cataclysm will not exceed 7 on the Richter scale.

Source: RIA Novosti


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