地震流体地球化学短临预测研究进展与展望

RESEARCH PROGRESS AND PROSPECT OF SEISMIC FLUID GEOCHEMISTRY IN SHORT-IMMINENT EARTHQUAKE PREDICTION

建立地震短临预测方法是减轻地震灾害损失的最有效手段,也是科学难题。流体是地球内部最为主动、活跃的组分,携带了地球各圈层的地球化学信息。地震流体地球化学的组成和变化对地下物理化学条件的改变响应灵敏,是指示地震和构造活动的有效指标。文中综述了国内外流体地球化学短临预测机理的研究进展,介绍了国内外已经建立的流体地球化学地震短临预测模型和方法,利用《中国震例》数据对主要预测模型和方法进行了检验分析,评述了各方法的适用性和效能。结合团队已有的工作基础,提出了基于前兆机理进行地震流体地球化学短临预测的思路,并对中国地震科学实验场地球化学子系统的地震短临预测研究和应用进行了展望。

Establishing the method of short-imminent earthquake prediction is the most effective way to reduce losses caused by earthquakes and is also an important scientific issue.In the 1960s and 1970s,research on earthquake prediction was carried out successively in China and other countries in the world,and after over 50 years of development,abundant precursor observation data and earthquake cases have been accumulated,and significant progress has been made in the research of formation mechanisms of precursor anomalies and prediction methods.Fluid is the most active component in the earth s interior,and the fluids in various layers of the earth often carry characteristic geochemical information.The composition and variation of seismic fluid geochemistry are sensitive to changes of underground physical and chemical conditions,making them powerful indicators of seismic and tectonic activities.The formation mechanisms of fluid geochemical precursor anomalies mainly include liquid mixing,water-rock reaction,deep magma upwelling,seismic wave vibration,pore compression and pressure solubility mechanism.The fluid chemical anomalies associated with earthquakes can be attributed to the migration process of liquid mixing and the water-rock reaction mechanism caused by crustal stress changes.This paper systematically summarizes the empirical formulas on the duration of anomaly,earthquake magnitude and epicentral distance,as well as the seismic fluid geochemical models and methods for short-imminent prediction established both domestically and internationally.In addition,four types of seismic fluid geochemical techniques and methods currently used in earthquake situation consultation in China are described.Nine of the most widely used prediction methods are selected to inspect the twenty-seven cases of earthquakes containing water radon or gas radon anomalies in the Earthquake Cases of China from 1997 to 2020.Generally,these methods all show strong applicability.However,empirical formulas based on different regions of the world selected to inspect the above cases generally show weak applicability.It indicates that current earthquake prediction models or methods are only representative to a certain extent,and there are still great difficulties in practical application,which also directly affects the prediction efficiency of the fluid geochemical models applied to the judgment of earthquake three elements.Combined with our previous results,the paper puts forward the applicable theory for the precursor mechanism-based short-imminent prediction by seismic fluid geochemistry,that is,acquiring the dynamic change characteristics of the geochemical field based on the spatio-temporal dense and multi-item observation network,establishing a deep-shallow coupling anomaly genetic model based on the material cyclic reaction,and determining the temporal and spatial relationship between the evolution of regional fluid geochemical field and fluid geochemical changes at each measuring point in the fault zone.The construction of the geochemical subsystem of China Seismic Experimental Site provides a platform for capturing the short-imminent earthquake anomalies and constructing effective fluid geochemical anomaly mechanisms and models.The causes and abnormal mechanism of fluid geochemistry can be revealed and the seismic fluid geochemical short-imminent prediction method can be established in the light of the principle of seeking the source by field and combining the field and source.