Seismic Hazard for Radioactive Tailing Areas
Seismic Hazard Assessment of the Radioactive Tailing Areas in Kyrgyz Republic
Tech Area / Field
- ENV-RWT/Radioactive Waste Treatment/Environment
- ENV-SEM/Seismic Monitoring/Environment
3 Approved without Funding
Institute of Seismology, NAS, Kyrgyzstan, Bishkek
- ANPA/Italian Agency for Environment Protection, Italy, Rome\nUniversity of Oregon / Department of Geological Sciences, USA, OR, Eugene\nUniversity of Colorado / Department of Geological Sciences and Cooperative Instiute for research In Environmental Sciences (CIRES), USA, CO, Boulder\nUniversity of Vienna / Institute of Risk Research, Austria, Vienna\nUniversity of Graz / Institute for Geology and Palaeontology, Austria, Graz\nRoyal Museum for Central Africa / Department of Geology and Mineralogy, Belgium, Tervuren
Project summaryAims of Project. The assessment of seismic hazard for four regions in the Kyrgyz republic where the radioactive tailings are concentrated and localization of those areas where the geodynamic effects of strong earthquakes (surface ruptures, landslides, rockfalls, etc.) can be developed; compilation of the database of the hazardous processes for the operative analysis of the geodynamic situation in the regions in question.
Urgency of the proposed studies is conditioned by the fact that numerous radioactive waste storages in Kyrgyzstan are located in the mountainous, tectonically and seismically active regions. Thus, strong earthquakes, as well as different modern geodynamic processes such as surface rupturing and slope failures associated with earthquakes and triggered by earthquakes pose the potential treat for these objects. Assessment of such a hazard is extremely important for substantiation of the measures for the environment protection and for minimization of the negative consequences of the hazardous processes.
The proposed Project was significantly improved according to the suggestions made by experts acquainted with its first version. We pay much more attention to detail study of the manifestations of the geodynamic processes at the specific sites and to their linkage with the regional tectonic deformations studied by the GPS and SAR observations. We take an opportunity to express our gratitude for thorough analysis of our proposal.
More than 75 millions cubic meters of radioactive waste tailings are accumulated in 49 waste storages in Kyrgyzstan. Total amount of tailings that contain heavy metals, cyanides, acid and other ecologically dangerous agents exceeds 620 millions cubic meters. These storages pose significant hazard to the environment.
Each year thousands earthquakes occur in Kyrgyzstan and about 10 events per year can be considered as hazardous. More than 10 destructive earthquakes occurred here in the last 150 years. The strongest events such as the 1885, M 6.9 Belovodsk, the 1911, M 8.3 Kemin, the 1946, M 7.6 Chatkal, the 1992, M 7.3 Suusamyr, were accompanied by large-scale tectonic deformations and slope failures, especially large within the fault zones.
Many of the radioactive waste storage areas are situated just near the large fault zones, characterized by mylonitization and intensive fracturing of rocks, their watering, i.e. by the conditions favourable for slope failures of different types. Especially dangerous are the active faults subjected to the intensive tectonic movements including those that occur during strong earthquakes. Usually the source zones of strong earthquakes, long surface ruptures, zones of large slope failures concentration are associated with such faults.
All these phenomena, either separately or in the aggregate, can destroy the storages, which may cause the catastrophic pollution of the environment. We must note that special study of active faults is obligatory for the design of nuclear power plants. It is undoubtedly, that large radioactive waste storages need the same consideration for their safety.
No complex seismic hazard assessment of the radioactive waste tailings that take into account possible geodynamic effects have been performed in Kyrgyzstan. Meanwhile, for example in Maily-sai, where 1374000 m3 of radioactive waste have been accumulated, several modern landslides which activity correlates with seismicity threaten these tailings (Torgoev et al., 1999). The above region is located several kilometers to the west from the active Talaso-Fergana fault which was, in particular, the source zone of the 1946, M 7.6 Chatkal earthquake. Its intensity at the Maili-sai was at least 6-7 points of the MM scale. Several smaller events that occurred nearer to the storage site also had the intensity about 7 points. Risk of these storages’ destruction is especially high since they are located upstream from the densely populated Fergana valley.
Of the large potential hazard are the radioactive waste storages near Kadjy-sai located not far from the regional Terskey fault. In case of their destruction the Issyk-Kul Lake can be polluted. One more region of the radioactive waste tailings is near the Mingkush town just nearby from the active faults bounding the neotectonic Mingkush-Kokomeren depression. This site is within the basin of the Naryn River – the main river of the Republic and the source of the Syrdaria River. The last region is near the Kara-Balty town in the densely populated Chu depression and, practically, in the epicentral zone of the strong 1885 Belovodsk earthquakes that was accompanied by large-scale surface ruptures and slope disturbances.
The official seismic zoning map of Kyrgyz Republic at the scale of 1:1,000,000 (1996) gives only general characteristics of seismic hazard and its detailed elaboration is necessary for the above regions. To guarantee the geodynamic safety of the enumerated tailings it is necessary to investigate and systematize potentially hazardous geological processes anyhow associated with the seismicity.
The Projects' implementation requires solution of the following tasks:
- Study of the active faults in the vicinity of the radioactive waste storages (Maili-Sai, Kadjy-sai, Mingkush, Kara-Balta), estimation of their displacement rates and regimes, values and kinematics of the single-event displacements and of their recurrence intervals corresponding to the strong earthquakes in these fault zones.
- Study of the modern geological processes in the tailing regions, first of all of the large-scale slope failures; assessment of the slopes' conditions and stability.
- Analysis of the data on the regional geodynamic processes derived from the GPS and SAR measurements; their correlation with the seismotectonics and local geodynamic processes.
- Study of the modern seismicity of the tailing regions, assessment of the parameters of the regional seismicity; study of correlation of the seismicity and slope processes.
- Compilation of the re-supplied database of the modern geodynamic processes in the radioactive waste tailing regions.
The proposed research methods
- The proposed studies are focused on the specification of the modern geodynamic conditions in the radioactive waste tailing regions. It requires utilization of the following research methods:
1. Analysis of aerial and space images for the purpose of mapping and segmentation of the active faults, localization of the areas affected by large-scale landslides and rockfalls.
2. Detail study of the selected active faults including their trenching; study of fault kinematics, average rate of slip, recurrence of rupturing events that can be interpreted as strong earthquakes. These data will allow to estimate magnitudes and recurrence intervals of the earthquakes associated with these fault zones, as well as the probability of the next strong earthquake, that can be expected at the studied fault segment.
3. Seismological observations by the local networks of permanent and temporary seismic stations in the selected areas. Analysis of the available seismological data for the previous period, including macroseismic data. It will allow to specify seismic regime of the regions in question, focal mechanisms of earthquakes.
4. Mapping of the different slope processes and study of their characteristics (landslide type, volume, present and past activity, distribution, etc.). Collecting of data on the relief, geological structure, geotechnical characteristics of different rock and soil types of the studied areas. Comprehensive analysis of these data will help to select potentially hazardous zones where seismically triggered landslides may occur.
5. Analysis of the modern regional tectonic deformations derived from the GPS and SAR measurements.
Data obtained during the proposed Project implementation will allow to study earthquake source zones in more details, to estimate the probability of the earthquakes occurrence within these zones and of the activation of hazardous geological processes in the tailing.
The results of these studies will be compiled in the data base, which will include data on the seismic regime, geological information, characteristics of the active faults and other information. It will also contain data on the landslides and rockfalls including local hydroheological and meteorological parameters. These database will be regularly supplied by the new information and will allow to obtain operative information on the state-of-the-art of the modern geological processes in the tailing areas and to predict its possible fluctuations. They will be used to specify the official map of seismic hazard of Kyrgyzstan.
- Complex assessment of the geodynamic and seismic hazard of the radioactive waste disposal storages for the Maili-Sai, Kadjy-sai, Mingkush, and Kara-Balta regions.
- Database on the modern geodynamic processes in the radioactive tailing regions that will be used for the generalization and operative analysis of the natural hazards.
- Recommendations for the Government of the Kyrgyz Republic with the purpose of development preventive measures for an abatement of ecological hazard in regions of a location of radioactive wastes.