Tajik scientist about seism durability of Rogun HPS

JuraevRahimjonUsmanovich – head of laboratory “Regional Seismology Institute of Geology, construction of seism durability and Seismology Academy of Science of Republic of Tajikistan. Occupation  engineer- geologist. Since 1976 carries on macro seismic inspection of aftereffects of strong and palpable earthquakes of Tajikistan, making up the catalog of palpable earthquakes, gathering and systematization of historical seismic events, which happened in Republic. He has got over 40 publication to this subject.

The problem is: What is importance of seismic conditions in surrounding of construction of hydro energy structure?

Solution: while construction and exploitation of safety big hydro structures in seismic active areas, among large complexes of special inspections, main role takes assessment of seismic threats. Seismic conditions of constructing area and assessment of maximum possibility of earthquake has main consequence. Tajikistan has already experience in building of high dams – its Nurek HPS, where all seismic parameters of area were taken under consideration. In conclusion of seismic monitoring, problems regarding inflame of seismic areas of Nurek HPS were particularly investigated. It was found that the excited earthquake in science-based mode filling of the reservoir, as a rule, cannot be stronger than the maximum possible earthquakes, calculated with the general seismic zoning. Seismicity (excited earthquake ) is can be adjusted by increasing or decreasing the water level in the reservoir . 

The problem: What is the situation in this respect in the design of building cascade in the middle and upper reaches of the valley of the river Vakhsh , including Rogun.  

Solution: The initial project of the Rogun hydroelectric power station was made at 1972-1978 years. Projects and survey and scientific research institute " SredazHydroproject". Beetle Tashkent, who was a leading research institute, and which has the best professionals of the time. Naturally then were taken into account seismic conditions of the construction site. When finalizing the draft Hydroproject Moscow in 2006-2009, were reviewed and considered all seismic parameters area. 

For the analysis of the seismic conditions of the construction site plant is extensive enough material for quite a long time: New catalog of strong earthquakes in the USSR (Section Central Asia and Kazakhstan ) from ancient times to 1975 , earthquake catalogs from 1955 to 2013 , the catalogs perceptible earthquakes for the period from 1941 to 2012, detailed macro seismic data on manifestations of strong earthquakes from 1895 to the present time and so on,which you can with reasonable certainty to evaluate the seismic conditions of any region in Tajikistan. These materials are generally only specialists. 

The problem is: what caused the publication of your book " Macro seismic manifestations of strong earthquakes in the area of construction of the Rogun HPP"? 

Solution: Recently, media and Internet sites appear different concoctions on the assessment of seismic conditions in the area of the Rogun hydroelectric power station. 

When evaluation of seismic conditions in the area of the facility , along with instrumental data records of earthquake parameters , a significant role for the study of macro seismic information about the historical strengths and tangible earthquakes have occurred in the area. It should be noted that even in the absence of instrumental records of macro seismic data processing technique allows to identify the main source parameters ( maximum score in the midst of its coordinates , magnitude , focal depth , etc.) with sufficient reliability.

This publication is the result of the collection and preparation of macro seismic information for the determination of strong earthquakes in combination with other parameters of seismic events as possible earthquakes ( maximum magnitude ) in the construction of the Rogun hydropower plant and the impact on the area of strong earthquakes in Tajikistan. 

This paper is devoted to a brief description of the strong earthquake was felt at the site of the Rogun hydroelectric power station with a different intensity. 

The author of the macro seismic data collected about the strong crustal earthquakes in the period from 1895 to 2012 occurred in the immediate vicinity of the Rogun hydroelectric power station, damaging seismic events occurred at a distance of 100 to 150 km away, and the most powerful of deep tremors , epicenters removed within 200 km or more . 

Presented and analyzed material gives a good idea of the maximum earthquakes and their manifestation in the construction of the Rogun hydroelectric power station. 

The strongest and most devastating earthquake in Tajikistan with M ≥ 6.0 is mainly confined to the main tectonic faults - Hissar- Kokshaal and Ilyaksk - Vakhsh faults. An analysis of the macro seismic data determined that the intensity of the manifestations of these earthquakes occurred at a distance of 60 to 160 km in the study area did not exceed 6 points.

As can be seen from the material published on the basis of the available macro seismic data for the period from 1895 and nearly 500 year period according to the "New catalog of strong earthquakes in the USSR (Section Central Asia and Kazakhstan ) from ancient times to 1975 in the immediate vicinity of the Rogun HPP earthquake intensity in the epicenter of more than 6-6.5 points with magnitude M ≥ 5.5 does not occur. Local earthquakes are mainly related to tectonic Lonahsh infringement which takes place in the immediate vicinity of the construction site , which is a measure of its features are not able to save energy for more strong earthquakes. The more so that the construction of this facility is designed for 9 points. 

It should be noted that at present the facility is working on the creation of a modern system of seismological , geological monitoring of the deformation and the experience of research previously conducted in the construction of the Nurek hydropower plant . 

PMPInternational » under the" Rehabilitation of the seismic network and the provision of geological , seismic and deformation monitoring Rogun district "for 2012 

When collecting materials used published literature , data collected directly by the author during the examination of earthquakes as a member of the Institute of Earthquake Engineering and Seismology (now the Institute of Geology, Earthquake Engineering and Seismology ) , Academy of Sciences of Tajikistan, the Main Department of Geology under the Government of Tajikistan and the Geophysical Service nearAcademy of Science of RT.