Crustal isostatic rebound in the lake Urmia area due to its desiccation

Lake Urmia is located in the northwestern of Iran. The geographic coordinates of this lake is between 37⁰ 03' to 38⁰ 17' North and 44⁰ 59' to 45⁰ 56' East. Lake Urmia is largest and saltiest permanent lake in Iran with a surface area of approximately 6000 km2, a length of 120 to 150 km, a width of 20 to 50 km, a maximum depth of 13 m, and Average depth of 6 m. Based on this, its average volume is estimated between 12 to 33 Milliard tones in times of aridity and wateriness, respectively. In recent years, environmental crisis and drying of about 85 percent of Lake Urmia water's, is considered one of the biggest geological hazards in the Azerbaijan region of Iran. Drying of Lake Urmia has been associated with a vast unloading on the surface of the crust. In this research, uplifting of the earth's crust (Isostatic Rebound) as a result of unloading due to the drying of Lake Urmia and the hazards caused by it have been investigated.

 In this research, uplift rate of crust (Isostatic Rebound)  is calculated based on: Unloading as a consequence of the Lake Urmia desiccation during 22 years (from 1375 to 1396) Density of fresh water (because of deposition of soluble and insoluble materials in water at the bottom of the lake) Regional isostasy (flexural isostasy) and the hazards of isostatic rebound has been investigated.

In this study, first the maximum amount flexure or depression due to the initial loading of water and its required parameters is estimated and then the amount of isostatic rebound (uplift) after loading from the surface of Lake Urmia as the result of decreasing water level and related parameters and the hazards of isostatic rebound has been investigated.

According to the estimates of this research, following the surface unloading of the lake Urmia, there are 85 mm uplift possibility, to balance the isostatic rebound. This uplift could be sudden in 22 years (0.39 cm/year) that, for confirmation, more comprehensive studies with sufficient data are needed. In this study, due to the lack or absence of sufficient data and the cost of data preparation and lack of time was not possible.AcknowledgmentsThis work was supported by the Ministry of the Sciences, Research and Technology of Iran and the University of Tabriz.