A Study On Fractal And Multifractal Properties Of Landform System And Seismic Crustal Deformation Fields

Based on the fractal theory, fractal and multifractal properties of landform system in Tianshan area, Xinjiang, China, are studied from different aspects and hieracies and by using different computing methods. Furthermore, the dynamic mechanisms of geomorphological formation and evolution are discussed. In addition, the pattern fractal and multifractal features of different periodical sesmic deformation fields are analysed.The fractal dimensions of elevation isolines in 6 studying sections from 3 different types of geomorphological zones, including high mountain, low-moderate mountain and catchment basin,are computed by using successive coarsening method. The results show that all the studied isolines are statistical fractals, and the fractal dimensions take on different characters for different geomorphological types and scale ranges. It can be inferred that the fractional dimension values are closely dependent on the erosional intensities, and it can be a very important parameter for dynamic geomorphological researches.By using the standard deviation method, the scaling properties described by the local fractal dimension D and crossover length tc of 48 measured landform profiles in different direction of 6 different studied landform sections are calculated . After that, the multifractal spectra Dq-q are computed by fixed-mass method. The results show that in the studied scaling range different types of landscapes and profiles in different directions perform different fractal properties, that is, the D value and crossover length ^ decrease in turns with the landform type from high-moutain, mid-low mountain to basin , and the profile parallel to wear grooves often has lower D values(<1.5) than those perpendicular to wear grooves do(1.5) in the same section. Furthermore, the Dq value ranges of profile multifarctal spectra in different landform types and in different directions of the same sections perform different properties and anisotrpies. It can be concluded that the landscape fractal properties depends closely on the intensity, manner and inhomogenity of exogenic and inogenic processess,and with the properties, we can study quantatively the dynamic geomorphic process.By using the same methods just above, local fractal dimensions D , crossover length tc and the multifractal spectra Dq-q of two large-scale landform profiles (across and along Tianshan mountain ranges respectively) are calculated .The results show that in the studied scaling range the two profiles perform different scaling properties ,and both of them can be divided to three evident different linear scaling subsections. In addition,the Dq-q curves behave in different shapes. It can be concluded that the scaling properties depend colsely on the way, intensity .acting scale and distribution in space of inogenic and exogenic processes. According to the scaling natures of the two landform profiles , it is proposed that the 5Km scale is the low limit of the inogenic process effects which begin to dominate landscape patterns in landform systems.By using the projective covering method and projective covering probability, fractal and multifractal dimensions of different types of landform sueface above are computed. Results show that all the studied landform surface are not simple fractals, but multi-range scaling fractals, and the fractal dimensions increase with the landform type from basin to mid-low mountain and highmountain. Nevertheless, different type landscapes perform different Dq-q curve shapes.which the Dq value has the widest range in the high mountain type, the second one is the mid-low mountain type, and then the basin type. It suggests that the fractal dimension value mainly depends on the exogenic process intensity and its processing scale range, and the Dq value range indicates inhomogenous distribution of the exogenic process intensity. According to the scaling natures of different type landform, it can be concluded that 5-6Km scale is the high limit of exogenic process effects which dominate landscape patterns.Usin...