| East Aisa has long suffered from seismic disasters, especially the great earthquakes in recent years, which has made disastrous influence on a broad area. Massive mortality and economic loss have been caused by India Gujarat earthquake in 2001, Iran Bam earthquake in 2003, China Wenchuan earthquake in 2008 and the massive earthquake in Japan in 2011, which are all occurred at the junction of seismic belt, including the east of Eurasian seismic belt and the northwest of circum-Pacific seismic belt. With varied topographic feature and complex geologic structure, the cause and mechanism of earthquakes in the regions have been a hot spot of research.The theory of fractal is gradually active and developed in the latest decade. In recent decades, researchers had done massive researches on the field of seismology, utilizing the method of fractal. This thesis, based on this theory, analyzed the seismic data in the above areas(80°E ~140°E, 20°N ~60°N).This paper, firstly, based on G-R law verified the integrity of the obtained earthquake catalogue(1970-2014, M>2.8), confirmed the minimum magnitude and divided the regions into sections according to their geologic structure and the trend of seismic belt.Then, using single fractal and multi-fractal this paper analyzed each section respectively, calculated the capacity dimension and information dimension of seismic time series and special distribution series in each section, and analyzed the change of seismic energy according to the trend of independent information dimension change of great earthquakes(M>7.0). The results show that despite different geologic background, the information dimension of seismic time series present decrease of different degrees before great earthquakes and increase after earthquakes, reflecting the accumulation and releasing process of seismic energy to some extent. Moreover, fractal parameter change of time series and special distribution series in dimensionless regions also reflect that these two series in every section show multi-fractal features, instead of single and uniform fractal structure.The first step in multi-fractal analyzing is to establish the fractal calculation model of seismic time series and special distribution series, and plot the double logarithmic chart of partition function and ?(q) ?q diagram of each section. The multi-fractal spectrum of the two series show that the seismic time series of Xinjiang province and its surrounding seismic areas and Qinghai-Tibet Plateau show distinct multi-fractal characteristics of sparse; that of North China shows multi fractal characteristics of intensive; and that of Pacific north west and north- south seismic zone earthquakes in China area show compound characters. The seismic spacial distribution series of north- south seismic zone earthquakes in China area show multi fractal characteristics of intensive; that of Qinghai-Tibet Plateau shows distinct multi fractal characteristics of sparse; and those of Xinjiang province and its surrounding seismic areas and Pacific northwest show compound characters.This paper, as a practical case for the combination the fractal theory and seismology, is a reference for fractal analyzing seismic data of structural belt, and providing basis for analyzing the time and spacial characters of earthquakes and forecasting earthquakes. |
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