| Earthquakes are one of the most serious natural disasters and seriously threaten the safety of human life and property.The gestation and occurrence of earthquakes are accompanied by the redistribution of the earth's internal mass,resulting in changes in the earth's gravity field.Flow gravity measurement is one of the important observation methods to obtain the time-varying signal of regional gravity field,and it plays an important role in earthquake monitoring and prediction.The earth's gravity field obtained by gravity measurement mainly includes tide and non-tide.The tidal part mainly includes solid tides,ocean tides,atmospheric tides,polar tides,and astronomical tides that exhibit periodic motions.These signals are the main factors that cause changes in the earth's gravity field,up to ± 240?Gal,and can be accurately calculated and corrected according to the model.The non-tidal part includes the effects of mass migration of the atmosphere,water,etc.and changes caused by tectonic activities.To study the gravity field change information caused by earthquake-related tectonic activities,it is necessary to deduct the gravity change caused by hydrometeorological factors from the flow gravity measurement results.In the practice of seismic analysis and prediction based on mobile gravity observation data,there is usually no actual measured data that is continuous or co-located with mobile measuring points,so quantitative analysis of changes in gravity field caused by hydrological and meteorological factors is rarely performed.Therefore,based on the GLDAS(Global Land Data Assimilation Systems)global hydrological model,this paper studies the impact of the global water cycle on mobile gravity measurement;and uses the meteorological station data and groundwater level data to simulate the spatial and temporal changes of soil moisture,and then studies the gravity effect of local land water;Use atmospheric models to study the effect of atmospheric mass redistribution on flow gravity measurements.The main research contents and results of this article are:(1)Pre-process the GLDAS global hydrological model data to obtain the equivalent water volume of each area distributed by the grid.Based on the load theory,the gravity load effect of land water on Xinjiang Jinghe Meteorological Observatory is calculated,and its annual change amplitude is 1.5?Gal;the gravity effect of land water on the mobile gravity measurement network in Xinjiang is calculated,and the change of land water on the two adjacent gravity measurements The influence of the net is less than 1.5?Gal.The processing of mobile gravity data in Xinjiang can ignore the impact of GLDAS global hydrological model.(2)Calculate the influence of the atmosphere on the gravity of Xinjiang Jinghe Meteorological Station based on the load theory.The amplitude of the annual change is about 8?Gal;calculate the gravity effect of the atmosphere on the mobile gravity measurement network in Xinjiang,and the redistribution of atmospheric quality to the two adjacent flows The gravity effect of the gravity measuring network can reach a maximum of 9.54 ?Gal;when the simulated flow gravity measurement section is closed for one,two,or three days,the influence of the atmosphere on the flow gravity measurement,the calculation results show that the atmosphere can have the greatest influence on gravity when closed for one day Up to 4?Gal,when the two days are closed,the influence of the atmosphere on gravity can be up to 6?Gal,and when the three days are closed,the influence of the atmosphere on gravity can be up to 8?Gal.In the processing of mobile gravity data,the influence of the atmosphere must be considered.(3)Using the meteorological station data(precipitation,evaporation,average temperature,average humidity,sunshine duration,wind speed),groundwater data to simulate the groundwater changes in Wuhan area,calculate the gravity field load effect,and use Wuhan superconducting data to verify the simulation calculation results.The results show that the simulation calculation can reproduce the seasonal and annual changes of superconducting gravity residuals,but there are still differences in amplitude and phase.In the later stage,the data of superconducting gravity and groundwater level co-location are needed to verify the reliability of the model,or consider the three-dimensional groundwater model to study the spatial and temporal distribution of groundwater in more detail.(4)Draw the gravity change chart before and after deducting the hydrological and meteorological factors.On the whole,the magnitude of the gravity change caused by the hydrological and meteorological factors is relatively small,the contour of the gravity change is slightly different,and the overall gravity change is not obvious difference. |
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