THE NASA satellites Landsat 8 and Landsat 9 resumed appearance in Caspian Sea off the coast of Azerbaijan the emergence of an island at the beginning of 2023 and its subsequent disappearance at the end of 2024. The “ghost island” was formed following the eruption of Kumani Bank mud volcanoalso known as Chigil-Deniz. It is not the first time that its eruptions originate these islands. Mud volcanoes, erupting structures mixtures of hydrocarbons, water and clayey sedimentsare typical of the areas located near i margins between two convergent lithospheric plateslike Azerbaijan.
The “ghost islands” in the Caspian Sea: how they are formed
The first eruption of Kumani Bank volcanolocated about 25 km off the east coast of Azerbaijan, dates back to 1861. Since then, his activity has produced numerous islands which have since disappeared. The last one made its appearance at the beginning of February 2023: satellites immortalized it together with a plume of sediment that spread into the surrounding waters. Initially the island was approximately 400 m widewhile at end of 2024 it had been almost completely dismantled by wave erosion. The eight previous eruptions of the Kumani Bank had created islands of different sizes, which disappeared in a more or less short time. For example, the 1861 event had produced an island just 87 m wide, while the 1950 event, the most intense, had formed one 700 m wide and 6 m high above sea level.

Azerbaijan’s mud volcanoes creating ‘ghost islands’
Kumani Bank is one of several mud volcanoes of Azerbaijan, where there are some more than 300most of which are found on land. These conical structures have a diameter varying between a few meters and several kilometers (in Azerbaijan they can reach one diameter of 10 km And 700 m high). Their formation is linked to the presence in the subsoil of large accumulations of organic matter whose decomposition releases it methane gas and of clayey sediments rich in water. In areas where intense compressive stresses actsuch as that of Azerbaijan (located where the Arabian and Eurasian plates converge), the gases and liquids present in the sediments are subjected to very high pressures which bring them up to the surface through the faults that characterize the earth’s crust in these tectonically active areas. The result is that theeruption of a mixture of water, hydrocarbons and sedimentswhich are deposited outside creating a conical mud structure. These eruptions can also be dangerous, since the gases emitted can generate very high flames.
Mud volcanoes are also present in Italy, for example in Sicily and in Emilia-Romagna. It is believed that these structures may have even formed on Mars.
