The driving forces behind the Caspian Sea mean water level oscillations |
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Authors: | Aziz Ozyavas Shuhab D Khan |
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Institution: | (1) Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX 77204, USA |
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Abstract: | Closed basins such as the Caspian Sea rapidly respond to variations in atmospheric and geological events. This study has been
conducted to deduce the role of natural and anthropogenic influences on the Caspian Sea mean water level fluctuations for
the period of 1998–2005. It is recognized that climate is the primary mechanism of the Caspian Sea mean water level variations
based on the relatively small differences of the Caspian Sea hydrologic budget residuals and the Caspian Sea mean water level
fluctuations. This is further supported by the similarity in water-level variations of the Caspian Sea with those of Lake
Van and Lake Urmia. On the other hand, the Caspian Sea needed to lose some of its water to attain water balance equilibrium
in 2000 and 2001. The year 2000 showed anomalous seismic activity particularly in the southwestern part of the Caspian Sea.
Two significant earthquakes with magnitudes of 6.8 and 6.5 Mw occurred on November 25, 2000. The focal mechanisms of these earthquakes and numerous aftershocks indicated normal faulting
and, therefore, caused the Caspian Sea lake level to decline in 2000. The contribution of submarine mud volcano eruptions
to the Caspian Sea lake level could be insignificant based on the comparison of water budget residuals and the mean water
level variations. Neither crustal deformation (based on the GPS measurements) nor the offshore oil and natural gas production
activities in the Caspian Sea are responsible for noticeable changes to the level of the Caspian Sea. |
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