Analysis and Study on the Change of the Observed Geo-electric Field Data at Lhasa Geomagnetic Station before and after the Nepal MS8.1 Earthquake

In this paper,the main purpose is to analyze and research the characteristics of the geoelectric field observed data with a long time span and large amplitude abnormal change,at the Lhasa geomagnetic station( hereafter referred to as "Lhasa station "),before and after the Nepal M_S8. 1 strong earthquake,which occurred on April 25,2015. Based on the observation conditions,the observation system,and the observed data of Lhasa station preliminary discussed,the main characteristics of the abnormal change and evolution process are analyzed and studied,using the following two methods; the "synthesis energy accumulation"and the "power as MSA spectrum"analysis,from the two aspects of the"Time Domain"and"Frequency Domain. "The results show that the abnormal change of the geo-electric field observation of Lhasa station experienced a development stage following the process of "trend change- disturbance change- earthquake period-recovery period",and an evolution process of "low frequency change- high frequency change- smooth change- high frequency change ",before and after the Nepal M_S8. 1strong earthquake. Comprehensive analysis shows that the variation characteristics and evolution process of the geo-electric field at Lhasa station are basically consistent with the results of the relevant mechanism and phenomenon research. So far,this is valuable information with certain objectivity,which is typical and representative to reflect the whole process of the gestation, occurrence and complete development of such strongearthquakes.