Temporal gravity variations due to Mississippi River bank infiltration near New Madrid, Missouri
Morrow, William S.
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Precision gravity surveys were conducted in the northern Mississippi Embayment area on an irregular basis between 1975 and 1978. Three gravity station pairs in the network have been reported to exhibit anomalous gravity changes between surveys. The statistically significant temporal change in gravity is due to a change in mass, a change in elevation, or both. This suggests that either tectonic activity or a change in river stage may be the responsible mechanism. The gravity station pairs all had one station in close proximity to the Mississippi River, suggesting a river stage-gravity change relationship. Changes in groundwater level induced by river stage changes were calculated by an equation analogous to heat flow. Gravity changes due to a change in river stage inducing a change in ground water level (bank storage) were calculated and found insufficient to produce the observed difference. However, correlation studies between calculated groundwater levels and observed gravity changes show a significant correlation and indicate that the gravity change is at least partly the result of bank storage, coupled with a possible river induced elevation change.