In this article,the vertical components of the continuous waveform data of 90 seismic stations in Ningxia and its adjacent regions recorded from January 2012 to December 2013 are used to obtain the Rayleigh surface wa...In this article,the vertical components of the continuous waveform data of 90 seismic stations in Ningxia and its adjacent regions recorded from January 2012 to December 2013 are used to obtain the Rayleigh surface wave group velocity dispersion images in the study area( 101°- 112°E,31°-42°N) according to the method of noise imaging,with period between 6s - 50s and resolution of 0.5°. The Yinchuan basin in the 6s - 26 s period obviously shows a low velocity anomaly,which is not uniform and has a tendency to gradually weaken; the Guanzhong Basin in 6 s-22s shows a strip of low velocity anomaly and demonstrates a transverse inhomogeneity,where velocity in the southeast is slightly faster than that in the northwest. In the 30s - 50s period it shows that in the Yinchuan graben basin and its southern area,there is a large low velocity anomaly area,which moves from northeast to southwest. It shows that between the main active tectonic zones,like mountains and basins,there are obvious geomorphologic boundaries. For example,the deep fault near Liupan Mountain is the dividing line between two large tectonic units of eastern and western of China. The inversion results have good correlation with the geological structure and the stratigraphic landform. The results are consistent with the results of artificial seismic section tomography across the basin. It provides an important basis for the dynamics of active tectonic zones and the mechanism of earthquake occurrence in this area.展开更多
Through the investigation on radioactive activities of water, sediment and some marine organismsin the Zhujiang Estuary, adjacent sea area and the distributary mouths of the Zhujiang River, activities of total α. rad...Through the investigation on radioactive activities of water, sediment and some marine organismsin the Zhujiang Estuary, adjacent sea area and the distributary mouths of the Zhujiang River, activities of total α. radioactivity, total β radioactivity, artificial radioactive 90Srand 157Cs, and factors inflencing the distribution and the content of U in seawater are studied.The mainly radioactive pollution substances and their sources in the sea area are studied by γ spectra obtained from sediment in the sea area. The results show that the main radioactivity substances are natural radioactivity U,Th series and 40K. which were produced by the modern industry and transported into the sea through the main current of the Zhujiang River.展开更多
[Objective] The research aimed to study the climatic characteristics of hail in the southern mountain area of Ningxia in recent 50 years. [Method] Based on the hail observation data of 5 surface meteorological station...[Objective] The research aimed to study the climatic characteristics of hail in the southern mountain area of Ningxia in recent 50 years. [Method] Based on the hail observation data of 5 surface meteorological stations (Guyuan, Xiji, Jingyuan, Longde, Liupanshan) in the south of Ningxia during 1960-2009, the spatial distribution rule, the interannual and monthly climatic characteristics and variation trends of hail in the south mountain area of Ningxia were analyzed by using the statistical method. Moreover, the hail disaster prevention and reduction measures in Guyuan were put forward. [Result] The hail in the south mountain area of Ningxia in recent 50 years had the obvious annual, seasonal, monthly and daily variation characteristics. The hail might occur from March to October and mainly concentrated during May-August which occupied 72% in the whole year. The occurrence probability of hail in June was the biggest and occupied 21.7% in the whole year. It was the typical multi-hail zone in summer. The interannual variation of hail occurrence in Guyuan was big and had 3-year periodicity. The secondary-order time trend of hail in Guyuan was the anti-parabolic type, and the hail occurrence times during the 1960s-1980s presented the increase trend. It was the hail multi-occurrence period in the 1970s and 1980s. After the 1990s, the hail presented the decrease trend. In recent 20 years, the hail significantly decreased. The hail in Guyuan mainly concentrated during 12:00-21:00, and the hail occurrence times occupied 85% of total times. The hail distribution in Guyuan area had the obvious regional characteristics. The hail in the mountain area, hilly area was more and in the stream valley, north Pingchuan area was less. The hail cloud mainly derived from the mountain areas, such as Liupanshan, Nanhua Mountain, Yueliang Mountain, Xifeng Mountain and Yunwu Mountain, etc. The move direction of hail cloud was mainly from northwest to southeast or from north to south. Part of hail cloud disappeared in the original place. According to the regional distribution of hail, the hail risk in Guyuan City was divided into the high, moderate and low occurrence zones by combining with the hail disaster data. [Conclusion] The research provided the scientific basis for the forecast, early-warning of hail weather and the artificial hail suppression.展开更多
基金sponsored by the Earth quake Science and Technology Spark Plan(XH14051YSX)the Natural Science Foundation of Ningxia,China(NZ15213)
文摘In this article,the vertical components of the continuous waveform data of 90 seismic stations in Ningxia and its adjacent regions recorded from January 2012 to December 2013 are used to obtain the Rayleigh surface wave group velocity dispersion images in the study area( 101°- 112°E,31°-42°N) according to the method of noise imaging,with period between 6s - 50s and resolution of 0.5°. The Yinchuan basin in the 6s - 26 s period obviously shows a low velocity anomaly,which is not uniform and has a tendency to gradually weaken; the Guanzhong Basin in 6 s-22s shows a strip of low velocity anomaly and demonstrates a transverse inhomogeneity,where velocity in the southeast is slightly faster than that in the northwest. In the 30s - 50s period it shows that in the Yinchuan graben basin and its southern area,there is a large low velocity anomaly area,which moves from northeast to southwest. It shows that between the main active tectonic zones,like mountains and basins,there are obvious geomorphologic boundaries. For example,the deep fault near Liupan Mountain is the dividing line between two large tectonic units of eastern and western of China. The inversion results have good correlation with the geological structure and the stratigraphic landform. The results are consistent with the results of artificial seismic section tomography across the basin. It provides an important basis for the dynamics of active tectonic zones and the mechanism of earthquake occurrence in this area.
文摘Through the investigation on radioactive activities of water, sediment and some marine organismsin the Zhujiang Estuary, adjacent sea area and the distributary mouths of the Zhujiang River, activities of total α. radioactivity, total β radioactivity, artificial radioactive 90Srand 157Cs, and factors inflencing the distribution and the content of U in seawater are studied.The mainly radioactive pollution substances and their sources in the sea area are studied by γ spectra obtained from sediment in the sea area. The results show that the main radioactivity substances are natural radioactivity U,Th series and 40K. which were produced by the modern industry and transported into the sea through the main current of the Zhujiang River.
文摘[Objective] The research aimed to study the climatic characteristics of hail in the southern mountain area of Ningxia in recent 50 years. [Method] Based on the hail observation data of 5 surface meteorological stations (Guyuan, Xiji, Jingyuan, Longde, Liupanshan) in the south of Ningxia during 1960-2009, the spatial distribution rule, the interannual and monthly climatic characteristics and variation trends of hail in the south mountain area of Ningxia were analyzed by using the statistical method. Moreover, the hail disaster prevention and reduction measures in Guyuan were put forward. [Result] The hail in the south mountain area of Ningxia in recent 50 years had the obvious annual, seasonal, monthly and daily variation characteristics. The hail might occur from March to October and mainly concentrated during May-August which occupied 72% in the whole year. The occurrence probability of hail in June was the biggest and occupied 21.7% in the whole year. It was the typical multi-hail zone in summer. The interannual variation of hail occurrence in Guyuan was big and had 3-year periodicity. The secondary-order time trend of hail in Guyuan was the anti-parabolic type, and the hail occurrence times during the 1960s-1980s presented the increase trend. It was the hail multi-occurrence period in the 1970s and 1980s. After the 1990s, the hail presented the decrease trend. In recent 20 years, the hail significantly decreased. The hail in Guyuan mainly concentrated during 12:00-21:00, and the hail occurrence times occupied 85% of total times. The hail distribution in Guyuan area had the obvious regional characteristics. The hail in the mountain area, hilly area was more and in the stream valley, north Pingchuan area was less. The hail cloud mainly derived from the mountain areas, such as Liupanshan, Nanhua Mountain, Yueliang Mountain, Xifeng Mountain and Yunwu Mountain, etc. The move direction of hail cloud was mainly from northwest to southeast or from north to south. Part of hail cloud disappeared in the original place. According to the regional distribution of hail, the hail risk in Guyuan City was divided into the high, moderate and low occurrence zones by combining with the hail disaster data. [Conclusion] The research provided the scientific basis for the forecast, early-warning of hail weather and the artificial hail suppression.
基金Challenge Programon Water & Food" Conservation agriculture for the dry-land areas of the Yellow River Basin"(CN228)"十一五"国家科技支撑计划项目"黄土高原水土流失综合治理工程关键支撑技术研究"(2006BAD09B04)欧盟DESIRE项目(037046)
