Environmental Earth Sciences

, Volume 65, Issue 6, pp 1821–1830

The driving forces behind the Caspian Sea mean water level oscillations

Original Article

DOI: 10.1007/s12665-011-1163-0

Cite this article as:
Ozyavas, A. & Khan, S.D. Environ Earth Sci (2012) 65: 1821. doi:10.1007/s12665-011-1163-0

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.

Keywords

Caspian Sea Water budget Climate Earthquake Mud volcanism 

Supplementary material

12665_2011_1163_MOESM1_ESM.doc (20 kb)
Lake Urmia water-level variations estimated from the T/P altimetry data starting from 1993 until 2008. Lake Urmia surface height has been in decline several meters since 1996. (Source is the U.S. Department of Agriculture’s Foreign Agricultural Service) (DOC 20 kb)
12665_2011_1163_MOESM2_ESM.doc (158 kb)
Map showing location of earthquake epicenters for 1998 in the Caspian Sea region. There were comparatively a few and not strong earthquakes within the Caspian Sea region. The magnitudes of the earthquakes within the Caspian Sea are between 3.6 and 4.5 (DOC 157 kb)
12665_2011_1163_MOESM3_ESM.doc (164 kb)
Map of earthquake epicenters in 1999 within and around the Caspian Sea with magnitudes 3 and larger. This year also was characterized by relatively weak and fewer earthquakes. The magnitudes of the earthquakes within the Caspian Sea ranged from 3.7 to 4.6 (DOC 163 kb)
12665_2011_1163_MOESM4_ESM.doc (158 kb)
Map showing the epicenters in and around the Caspian Sea during 2001. The strongest earthquake indicated by orange circle had a magnitude of 5.2 offshore the coast of southern Apsheron peninsula within the Caspian Sea. The rest of the magnitudes of the earthquakes in the Caspian Sea ranged between 4.1 and 5 (DOC 158 kb)
12665_2011_1163_MOESM5_ESM.doc (161 kb)
The location of epicenters of earthquakes that occurred in 2002. This year was characterized by relatively low seismic activity within and around the Caspian Sea. The earthquakes within the Caspian Sea have magnitudes between 3.5 and 5 (DOC 160 kb)
12665_2011_1163_MOESM6_ESM.doc (148 kb)
Earthquake epicenters are shown for 2003. Even though there are no significant earthquakes, 2003 is marked relatively higher number of earthquakes preceding 2000. Most of the earthquakes were concentrated in the middle Caspian Sea. The 3.9 and 4.7 were the minimum and maximum magnitude earthquakes. There was a quite seismic period around the margins of the Caspian Sea (DOC 148 kb)
12665_2011_1163_MOESM7_ESM.doc (159 kb)
Location of epicenters of earthquakes in 2004. Many earthquakes were located along the margins of the Caspian Sea including the strongest one (magnitude 6.3) in the Alborz Mountains. The number of earthquakes within the Caspian Sea was relatively small with magnitudes between 3.5 and 4 (DOC 158 kb)
12665_2011_1163_MOESM8_ESM.doc (587 kb)
ASTER image band 3 (Near-Infrared) displayed as gray scale image. This image was acquired on July 23 2000. Natural oil slicks forming mutiple half circles around a mud volcano island indicate subaqueous mud volcanic eruptions. Oil slicks are black in color on the water surface. Double triple oil slicks may indicate subsequent submarine eruptions. The lighter color of the sea surface in comparison to Landsat images is probably because of the very thin cloud cover. The location of this satellite image is shown in Fig. 8 as Site 2 (DOC 586 kb)
12665_2011_1163_MOESM9_ESM.doc (157 kb)
A Landsat image of the same mud volcano island displayed as gray scale image (band 4, Near Infrared, equivalent to Band 3 in ASTER). This Landsat scene without cloud cover was acquired on June 30, 2000. Water becomes totally black in near infrared wavelength and no oil slicks can be seen on the Caspian Sea surface (DOC 157 kb)
12665_2011_1163_MOESM10_ESM.doc (184 kb)
Landsat image data acquired on January 8, 2001. Note that oil slicks are not present around the same mud volcano island. Band 4 (Near Infrared) The Landsat image is without any cloud cover (DOC 184 kb)
12665_2011_1163_MOESM11_ESM.doc (382 kb)
An ASTER image of natural oil slicks on the water surface of the Caspian Sea indicated as Site 3 in Fig. 8. The scene is acquired on July 23, 2000. The multiple repetitions of oil slicks may indicate several consecutive eruptions of a submarine volcano. Thin clouds present at the acquisition time of this ASTER image gave rise to dark gray color for the sea surface (DOC 381 kb)
12665_2011_1163_MOESM12_ESM.doc (137 kb)
Landsat image acquired on June 30, 2000 (before July 23, 2000 oil slick) does not show circular oil slicks on the Caspian Sea for the same location shown in Fig. 11a. The water surface appears black due to the fact that near Infrared wavelength used in this image in gray scale is absorbed by the water (DOC 137 kb)
12665_2011_1163_MOESM13_ESM.doc (206 kb)
Landsat image acquired on January 8, 2001 over 5 months after the July 23, 2000 shows no oil slicks in the same area. This image display was made using a Near Infrared (band 4) wavelength in gray scale (DOC 205 kb)
12665_2011_1163_MOESM14_ESM.doc (376 kb)
Natural oil slicks in the Baku bay shown in Site 1 in Fig. 8 observed by ASTER image acquired on July 23, 2000. A gray scale image of Near Infrared wavelength (band 3) was used in this image. The reason for using this wavelength is that natural oil slicks and sea surface made a strong contrast to be distinguished (DOC 376 kb)
12665_2011_1163_MOESM15_ESM.doc (319 kb)
This Landsat image for the same area shown in Fig. 11a was acquired on June 30, 2000 (before the oil slick). The image show Baku bay, water surface was free from oil slicks. Near Infrared wavelength (band 4) in Landsat data is used to generate the image (DOC 318 kb)
12665_2011_1163_MOESM16_ESM.doc (414 kb)
The Landsat image of same area shown in 22 and 23 acquired on January 8, 2001(after the spill). The oil slicks observed on July 23, 2000 ASTER image are not seen (DOC 413 kb)
12665_2011_1163_MOESM17_ESM.doc (14 kb)
Oil and Natural gas production in the Caspian Sea region. No oil production data for production in Russia was available (Modified from Gelb 2006) (DOC 14 kb)

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  1. 1.Department of Earth and Atmospheric SciencesUniversity of HoustonHoustonUSA

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