甘肃岷县漳县6.6级地震发生日期的触发因素分析及对短临预测方法的思考

短临预报是目前地震预测的难点,通过对2013年甘肃岷县漳县MS6.6地震发生日期的研究,发现发生日期7月22日是节气、低点位移、异年倍七律和朔望共同作用的时间点。据此,本文用一些基于可能触发地震发生的非传统方法的时间预测方法,回顾性地讨论了甘肃岷县漳县MS6.6地震发生日期的临震日期预测问题。通过对岷县漳县MS6.6地震研究,认为在地震短临日期的预测上。一些非传统方法虽然在机理上还有待研究,但在统计上多次证明该方法具有预测准确性的效能。要基于传统方法与非传统方法结合,才能对临震预测的时间逼近,同时提出今后预测临震时间的思路:多因素不断拦截法。

Analysis of Trigger Factors of the Minxian-Zhangxian M_S6.6 Earthquake Occurrence Date and Short-impending Prediction Methods

Statistics of earthquake occurrence dates predicted for many years by Chinese earthquake researchers indicate that earthquakes often occur on the dates of solar terms,displacement of geomagnetic low points,and the first and the fifteenth days of lunar months,which agree well with earthquake statistics. Twenty-four points were set during a one-year period on the basis of sun position.Each point is referred to as a solar term,which generally refers to the day it was recorded. The value of the strength of the magnetic field in a direction perpendicular to the ground (Component Z)was generally lowest at 12:00each day but occasionally occurred before or after that time.In such instances,the low point is said to be"displaced" ." Quiet day" is a technical term that refers to daily changes.Thus,lowest points occurring at times other than 12:00are noted by"displacement of low point of Component Z on quiet day" .Displacements of low points at certain times measured by all magnetic observatories are marked on a map as postponed in some regions for 2hor 4hor are indicated as not postponed.These displacements are demarcated by adisplacement line of low point,in the vicinity of which earthquakes often occur.Dangerous earthquake generation generally occurs 27and 41days(±4days)following formation of the displacement line.Syzygy occurs when the Earth,Sun,and Moon are in a straight line.The first day of the lunar month occurs when the Moon circumambulates between the Sun and the Earth,and the dark face of the Moon is directed toward the Earth.The fifteen or the sixteenth day of the lunar month occurs when the Moon circumambulates back to the Earth,and the hemisphere illuminated by the Sun faces the Earth.The sevenfold and ninefold rules in various years are indices used in impending earthquake prediction that were proposed by the author in 1986.We determined that if strong earthquakes of different years occur in a certain region during the same or similar seasons,the interval of their occurrence dates was a multiple of seven or nine days.This time interval characteristic of sevenfold and ninefold rules in different years enables accurate prediction of the dates of future strong earthquakes in particular regions based on the historical dates of strong earthquakes in the same area.In this study,the July 22,2013,occurrence date of the Minxian-Zhangxian MS6.6earthquake is analyzed on the basis of such triggering factors,and a number of concepts and methods of short-impending prediction are presented on the basis of these phenomena.