Discussion On Useing Geogas And Emanation Prospecting Method To Infer The Actives Of Fault

Since the introduction of geogas measurement technology in China from the 80’s of the last century,it has been the rapid development.This technology is becoming more and more mature, especially widely used in the detection of concealed ore body and buried faults, the result has been widely recognized. At the same time, in 1979,after the Japanese scholar Kato in the use of alpha particle track method to study the active fault of rice —big mountain,the shallow mountain,the Izu Peninsula and Fuji Sichuan area,he put forward the model of shallow layer of radon concentration and location of activity fault,the topic of radon gas or water radon measurement to monitor the activities of faults is proposed, in theory,the Rn because of its short half-life, that can be rapidly detected after the ground crack was formed,and therefore can be used to judge the recently active of the fault,and the concentration of a sudden rise or reduce it may be a precursor to large earthquakes, radon measurement is difficult in the actual work, but to judge from the concentration decay balance of its decay daughter Pb and Bi can be indirectly inferred Rn. In recent decades,daily monitoring is widely used in seismic monitoring stations, and achieved certain results, but because of its characteristics of high sensitivity, so that the possibility of interference is relatively large, so the earthquake prediction of radon is controversial.In order to find out the relationship between the radon gas and the fault, active fault and unfault, based on the analysis of geological survey project and the data measured, a detailed study of the relationship between the three is done.The two study areas were located in the important orogenic belt witch called Himalaya orogenic belt and the Lancang River orogenic belt by scholars, the belt provides a good background of the active fault and fault’s development, and also provides a good research environment to achieve the research purpose.In the Yarlung Zangbo Suture Zone,we selected two faults witch were uncertained by previous as the research object,named the Niyang River fault and Yu Song fracture. Through the method of Geogas measurement and radon measurement, made a large number of original data, compared to the local background values of elements,we confirmed the threshold determination of anomaly, and make the element graph. We found that element anomaly in Niyang River fault is chaos, there is no multi element anomaly superposition; Yu Song fault’s measurement results reflect the coincidence relation, especially the abnormal position of Pb and Bi witch is the decay daughter of Rn is consistent with other element’s anomaly location,so we speculated that the Niyang River fracture does not exist and Yu Song fracture exists and is an active fault, in order to verify the inference,we have a field investigation and found that the field performance is consistent with the inference.In Goujie Yunnan,we choosed Goujie fracture F7 and two secondary faults f6-6 and f6-5 witch on the east side of the Lancang fault F6 to study, these three faults well exposed in the field,the characteristic of fault is obvious, so in order to verify the hypothesis of geogas anomaly and radon(or its decay daughter) was normal, that could infer the fault exists but not an active faults, we layout A, B, D, N four gas section to study,we found the abnormal position of elements was a high degree of overlap, but there is a profile A with no abnormal, but can be introduced the concentration of Rn is very small witch conclusioned indirectly through Pb and Bi. B, D, N profile showed no abnormal,that means there is no decay balance phenomenon of the two kinds of radon’s decay daughter in the fault, that is to say Rn is not unusual, so that the previous assumption is established. Study of the relationship of geogas or radon and three faults,the geogas research combined with the radon’s messurement to determine the presence of faults and the activity of the proposition is correct.At the same time, in order to apply the theory to practice,after explaining the relationship between earthquakes and active faults, we put forward the geogas and the radon can be measured to predict earthquakes, but from the operational point of view, the emanation measurement method to predict the earthquake is poor actual operation.