地震预测方法Ⅵ:气体地球化学方法

Earthquake prediction Ⅵ:gas geochemical method

地球化学地震预测方法是常见的地震预测方法,该方法通过研究地球化学组分在地震前的异常变化,得到其变化规律,推导其与地震三要素的关系,从而进行地震预测.气体地球化学预测则是通过震前气体异常给出预报意见.因为地球的脱气作用一直存在,震前震源区岩层岩石力学性质会发生很大改变,导致大量流体涌出,渗透性较好的活动断层为深部流体提供了通道,使它们能更容易地到达地表,造成地表断层带土壤气体(简称断层气)组分异常,为地震预测提供了依据.本文主要介绍断层气气体异常、温泉气气体异常、遥感气体异常几部分.常见的气体地球化学异常组分主要有土壤氡、H_2、CO、CO_2等,这些气体测值在震前会出现明显的异常,多数为突跳式升高、降低,异常幅度变大,异常持续时间增加等等.我们分析了这些异常的特征,并且从地震三要素出发,判断二者之间的关系,从而对气体化学地震预测方法进行评价.由于气体的活动性较好,因而容易将地下孕震信息带到地表,气体化学异常的映震性较高,所以该方法极少虚报,但存在漏报的可能性,仍然需要与其他地震预测方法相结合从而增加地震预测的准确性,不能单独完成地震预测.

The geochemical prediction method is a common method for predicting earthquakes. By studying the anomalous changes of geochemical components before earthquakes and getting the law,the relationship between them and the three elements of earthquake will be deduced. The gas geochemical method is applied to predict earthquakes by using the gas anomalies before earthquakes. Because the degasification of the Earth has always existed,the rock mechanics properties of the rock in the epicentral area before the earthquakes are greatly changed,resulting in a large amount of fluid gushing,and the active faults with better permeability provides a channel for the deeper fluids easier to reach the surface,causing the anomalies of soil gas（ the fault gas） in the surface fault zone,which provides the basis for earthquake prediction. The major components of gas and geochemical anomalies are soil radon,H_2,CO,CO_2,etc.These gas measurements show obvious anomalies before earthquakes,most of which are sudden jumping rises,decreases,abnormal amplitude rises,abnormal periods increasing and so on.We analyze the characteristics of these anomalies,from the three element of earthquake,we determine the relationship between the two,so as to evaluate the gas chemical earthquake prediction method. Because of the good gas activity,it is easy to bring the underground seismogenic information to the surface. The gas chemical abnormalities are of high reflection,so the method rarely false. But there are possibilities of omission,so it are is hard to make right prediction using this method only,still needing to combine other methods to increase the accuracy of earthquake prediction.