Investigation on the relation between the gravity anomaly，crustal deformation and underground water

Ｉｎｖｅｓｔｉｇａｔｉｏｎｏｎｔｈｅｒｅｌａｔｉｏｎｂｅｔｗｅｅｎｔｈｅｇｒａｖｉｔｙａｎｏｍａｌｙ，ｃｒｕｓｔａｌｄｅｆｏｒｍａｔｉｏｎａｎｄｕｎｄｅｒｇｒｏｕｎｄｗａｔｅｒＸｕｅ－ＦａｎｇＷＵ（吴雪芳），Ｓｈｉ－ＨｕａＴＩＡＮ（田世华）ａｎｄＧｕ...

Investigation on the relation between the gravity anomaly,crustal deformation and underground water

Trough the practice of earthquake prediction we have found that sometimes an earthquake doesn' t occur in the gravity anomaly region or the magnitude of earthquake that has occurred does not corrrespond to the value of gravity anomaly. The main reason of this is related to crust deformation or behavior of undergroud water.In this paper, based on the theory of elasticity and dynamics, the gravity effect associated with the elevation variation, density change and mass migration under the observation point as well as the relationshipe between gravity of feet and crustal activity are studied. The relationship between the variation of gravity and crust vertical deformation, underground water, precipitation are researched; besides the order of magnitude, time and pattern of the influence are studied in order to obtain the gravitational precursors directly related to earthquakes.Theory and practice have proved that crust deformation caused by pumping underground water or extracting petroleum and gravity changes are linearly related. This paper shows that the effect and influence produced by different aquifers to the gravity changes are also different. Phreatic water is the main factor which causes the gravity changes. The second factor is precipitation which influences the humidity of soil, as a result the gravity changes. The confined water, when there is no pumping, whatsoever the rise or fall of its level almost has no influence on the gravity changes.Observation data of Northern China and areas of South-western China verified the consistency of practice with theory.