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标题：Fractal and Morlet-wavelet analyses of M ≥ 6 earthquakes in the South-North Seismic Belt, China
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作者：Jeen-Hwa Wang ; Kou-Cheng Chen ; Kao-Hao Chang 等
期刊名称：Terrestrial Atmospheric and Oceanic Sciences
印刷版ISSN：1017-0839
出版年度：2017
卷号：28
期号：6
页码：799-814
DOI：10.3319/TAO.2017.01.25.01
出版社：Chinese Geoscience Union
摘要：The M ≥ 6 earthquakes occurred in the South-North Seismic Belt, Mainland China (longitudes from 98 - 107°E and latitudes from 21 - 41°N) during 1900 - 2016 are taken to measure the multifractal dimensionsspatial distribution and time sequence of events and the dominant periods. The multifractal dimensions, D q , are measured from the log-log plots of C q (r) versus r and C q (t) versus t, where C q (r) and C q (t) are the generalized correlation integrals for the epicentral distribution and time sequence of events, respectively. r and t are the epicentral distance and inter-event time, respectively, at positive q. The log-log plot of C q (r) versus r shows a linear portion when log(r l ) ≤ log(r) ≤ log(r u ). The r l and r u values are, respectively, 120 and 560 km for M ≥ 6 events, 100 and 560 km for M ≥ 6.5 events, and 63 and 560 km for M ≥ 7 events. The r l value decreases with the lower-bound magnitude. D q monotonically decreases with increasing q. The D q values are between 1.618 and 1.426 for M ≥ 6 events, between 1.562 and 1.108 for M ≥ 6.5 events, and between 1.365 and 0.841 for M ≥ 7 events. The log-log plot C q (t) versus t show a linear distribution when log(t l ) ≤ log(t) ≤ log(t u ), where t l and t u are, respectively, 5 and 50.1 years for M ≥ 6 events, 5 and 50.1 years for M ≥ 6.5 events, and 16 and 63.1 years for M ≥ 7 event, thus suggesting that the time sequences of earthquake in the study region are multifractal. The D q values are between 0.830 and 0.703 for M ≥ 6 events, between 0.835 and 0.820 for M ≥ 6.5 events, and between 0.786 and 0.685 for M ≥ 7 events. The Morlet wavelet technique is applied to analyze the dominant periods of temporal variations in numbers of yearly earthquakes for the three magnitude ranges, i.e., M ≥ 6, M ≥ 6.5, and M ≥ 7. The resultant dominant period is 2.94 years for M ≥ 6 events and cannot be evaluated for M ≥ 6.5 and M ≥ 7 events.
关键词：Multifractal dimension; Earthquake sequence; Epicenter; Inter event time; Morlet wavelet technique; Dominant period;