基于速率累加算法的地磁谐波振幅比异常分析

随着观测数据的积累和地磁谐波振幅比方法的推广,近些年积累了丰富的地磁谐波振幅比异常震例,但地磁谐波振幅比异常的识别困难,而"形变速率累加方法"对异常数据进行积分计算,更加易于异常的判定和异常指标的提取。基于此,使用2013年1月至2017年12月临汾台、湟源台和成都台地磁分钟值数据,计算得到各台地磁谐波振幅比南北向和东西向6个周期共计12条时间序列变化曲线,再运用速率累加方法对地磁谐波振幅比南北向和东西向各周期的计算结果进行二次计算,得到6条各周期的速率累加时序变化曲线。研究结果表明:①临汾台、湟源台和成都台三个台站地磁谐波振幅比速率累加方法计算结果分别在2016年山西运城4.4级地震、2016年青海门源6.4级地震和2017年四川九寨沟7.0级地震前出现异常,其异常表现为:6条速率累加曲线(6个周期)至少有2条出现超过1年以上的持续下降或水平波动变化(持续上升变化为正常);②速率累加方法使得地磁谐波振幅比异常更易识别、异常特征的统计更加准确,且与原有的地磁谐波振幅比异常判别结果基本一致。

The Anomaly Analysis on Geomagnetism Harmonic Amplitude Ratio based on Rate Accumulation Algorithm

With the accumulation of observation data and the popularization of geomagnetic harmonic amplitude ratio method, plentiful geomagnetism harmonic amplitude ratio abnormal earthquakes have been recorded in recent years, but it is difficult to identify geomagnetic harmonic amplitude ratio anomalies. However, the deformation rate accumulation method is easy to determine anomalies and extract abnormal indexes by integral of abnormal data. On the basis of this situation, total 12 time-series curves of geomagnetic harmonic amplitude ratio are calculated using the geomagnetic minute data from January 2013 to December 2017 at Linfen, Huangyuan and Chengdu station. Then the rate accumulation method is used to calculate the results in each period of magnetic harmonic amplitude ratio in the north-south direction and the east-west direction. Six time-series curves of rate accumulation in each cycle are obtained. The results show that: (1) anomalies are distinguished by the geomagnetic harmonic amplitude specific rate accumulation method at Linfen, Huangyuan and Chengdu station before the 2016 Yuncheng 4.4 earthquake in Shanxi Province, the 2016 Menyuan 6.4 earthquake in Qinghai Province and the 2017 Jiuzhaigou7.0 earthquake in Sichuan Province, respectively. The anomalies are as follows: at least 2 of the 6 rate accumulation curves (6 cycles) show continuous decline or level fluctuation for more than 1 year (continuous rise is normal); (2) the rate accumulation method is easier to identify the abnormities in geomagnetism harmonic amplitude ratio data and is more accurate in abnormal characteristics statistics. The results are basically consistent with the original geomagnetism harmonic amplitude ratio anomaly discrimination results.