山西地震带历史地震序列的极大熵谱分析

MAXIMUM ENTROPY-SPECTRUM ANALYSIS OF HISTORICAL EARTHQUAKE SEQUENCE IN SHANXI SEISMIC ZONE

本文综述了极大熵谱分析的原理及Burg递推算法,选取应变能E_i^(1/E_i)和地震活动度A_i为采样序列对三个时间段1300—1988年、1400—1988年和1500—1988年进行了极大熵谱分析,结果表明,山西地震带中强震活动的显著周期对E_i^(1/E_i)序列三个时间段的平均值是(35±1)年,(65±4)年和(135±3)年以及321年;对A_i序列三个时间段的平均值是(35±1)年,(66±3)年和(130±3)年以及347年,两个序列所得结果较为一致。其长周期321年和347年与华北地震区第二、第三活动期持续时间330年和361年较为一致,可见山西地震带中强震的活动和华北地震区中强震的活动同步变化,且主要受显著周期321年、347年的控制;其短周期35年和66年与太阳活动和地球自转的31年和60年长周期较接近,表明地震活动在总体上受太阳活动与地球自转速率变化控制,短周期成分反映了该区区域应力场的积累和释放特点。

The principle of the maximum entropy analysis and the Burg recurrence algorithm have been described in this paper. The sampling sequences of the strainenergyy and degree of seismic activity Ai have been chosen to carry out the ma-ximum entropy analysis on three time interval of 1300-1988, 1400-1988 and 1500-1988. Results show that the average periods of strong earthquake activity in Shanxi seismic zone for the three time intervals of sequence are (35±1),(65 ± 4), (135 ± 3), and 321 years; the average periods for the three time intervals of Ai sequence are (35±1), (66±3), (130±3), and 347 years. The results obtained from the two sequences are relatively unanimous. Their long periods of 321 and 347 years are comparatively consistent with the time duration (330 and 361 years) of the second and third active periods in North China seismic region It can be seen that activities of strong earthquake in Shanxi seismic zone and those in North China seismic region change synchronously and mainly controlled by the salient periods of 321 and 347 years; the short periods of 35 and 60 years are relatively close to the long periods of 31 and 60 years of the solar activity and the Earth rotation, that seems that seismic activities are generally controlled by the solar activity and the rate variations of earth rotation, and that the short period constituents reflect the features of regional strees accumulation and release in this area.