Key Takeaways:
- Satellites recorded a temporary landform in the Caspian Sea now known as a Caspian ghost island.
- The feature formed in early 2023 after an eruption of the Kumani mud volcano and began to erode by late 2024.
- Scientists say mud volcanoes expel sediment and gas rather than lava, producing unstable, short lived landmasses.
- Researchers hope real time observation of future eruptions will clarify whether tectonics or gas ignition trigger such events.
Satellites detected a patch of new land rising from the Caspian Sea in early 2023 and then watched it wash away over the following year. The transient feature, tracked about 25 kilometres off the coast of Azerbaijan, was captured by imagery from NASA Earth Observatory and has been identified as a temporary landform produced by an eruption of the Kumani mud volcano.
Caspian ghost island appears and fades
The so called Caspian ghost island emerged where, until late 2022, only open water existed. By February 2023 satellite platforms recorded a clearly defined area of exposed sediment and clay. Local and international geologists took immediate interest because such formations are rare and short lived. By the end of 2024 the feature had begun to collapse and return beneath the waves.
Unlike magmatic volcanoes that expel molten rock, mud volcanoes bring up a slurry of mud, clay, sediments and gases. When a vigorous eruption forces large volumes of this material above sea level it can, for a time, create a visible island. The deposit is unconsolidated and vulnerable to erosion, which is why these islands rarely persist.
How the Kumani mud volcano builds temporary land
The Kumani Bank, an underwater mud volcano, appears to have pushed a mound of sediment to the surface during an active episode. Observations show mud volcano eruptions can be energetic. They release gases that sometimes ignite and produce flames at the vent. That combination of expelled sediment and gas can produce a mound of material substantial enough to be seen from space.
Marine waves and currents act quickly on such deposits. Unlike solid lava flows, the mud and silt that form these islands lack cohesion. Wave action and tidal movement rework the material, and over months or a few years the landmass disperses and sinks back beneath the sea.
What scientists still want to know
Although the mechanics of erosion are well understood, the triggers for a mud volcano eruption remain under study. Researchers propose two leading explanations. One links eruptions to tectonic stress and movement of underlying sediments and fluids. The other points to sudden gas release and self ignition as a contributor to explosive activity. To confirm either hypothesis scientists need to observe an eruption from its onset, which requires continuous monitoring and a measure of good fortune.
The Caspian ghost island near Azerbaijan is not an anomaly in terms of process, but it is a valuable opportunity for study. Such transient features can yield information about sub‑sea sediment dynamics, gas venting and regional tectonics. For countries bordering the Caspian Sea, including neighbouring states that are members or partners of BRICS+, improved monitoring could advance hazard assessment and scientific collaboration.
For now the island has largely disappeared, a reminder that some geological events are brief yet instructive. If Kumani Bank renews its activity, another temporary island could appear. Scientists will be watching with instruments and satellites ready to capture the event if it unfolds again.
