ncdc logo title
Emergency response service of scientific data for Tajikistan M 7.2 earthquake (20230223)
According to China Earthquake Networks: An earthquake of magnitude 7.2 occurred in Tajikistan at 08:37 local time on February 23, 2023. The epicenter was located at 37.98 degrees north latitude and 73.29 degrees east longitude, with a focal depth of 10 kilometers, about 82 kilometers from the nearest border of China.There are 10 large and medium-sized cities within 300km of the epicentre, the nearest being Khorog, about 162km away.The earthquake caused a strong sense of earthquakes in Kashgar, Xinjiang.In the past 11 years, there have been 621 earthquakes of magnitude 3 or above within 200 kilometers, among which there have been 3 earthquakes of magnitude 7 or above, and the largest one was 7.4 on December 7, 2015.No casualties or damage have been reported. The National Cryosphere Desert Data Center (NCDC) for Glaciology and Permafrost Desert collects and prepares basic geographic data, satellite remote sensing data, population data, topographic data and other emergency response scientific data based on disaster situations.The "Emergency response service of scientific data for Tajikistan M 7.2 earthquake (20230223) " system has been released, which provides data visualization, interoperation and data download capabilities.For use by relevant emergency, rescue and research departments. The subsequent NCDC will continue to further collect and sort out various data resources in the earthquake area and gradually release them through the data center platform for the use of relevant emergency, rescue and research departments. Service Website:
New Models
A large number of reservoir inflow with preserved data, spillway discharge and discharge of breach ditch (unstable flow with sediment transport capacity) formed along erosion are comprehensively applied in the model. It is assumed that the slope ratio at the bottom of the breach is basically the same as that at the downstream of the dam. The development of breach ditch depends on the material properties of dam body (D50 size, unit weight, friction angle, bond strength). The model takes into account the following possible complexities: 1) the material properties of the dam core and the outside of the dam are different; 2) before the real breach caused by overtopping flow is formed, the erosion ditch along the downstream slope surface of the dam is determined; 3) the downstream slope of the dam may be covered with grass or contain materials larger than the external components of the dam; 4) the shear strength and cohesive force are exceeded The results show that more than one sudden structural collapse mechanism is enlarged due to the hydrostatic pressure; 5) the width of the breach obtained from the slope stability theory is enlarged; 6) the free surface breach flow is developed by piping, which causes the collapse; and 7) the non cohesive material (gravel) or cohesive material (clay) may be carried away by erosion. The discharge water level hydrograph is obtained by time step iterative method, which can be completed in only a few seconds on a main computer. The model is not constrained by numerical stability and convergence stability.