Mud volcanoes of Azerbaijan are an estimated 300 formations found mainly around the Azerbaijani city of Baku and along the coast of the Caspian Sea. Mud volcanoes are bubbling pools of mud that resemble lava volcanoes. Unlike lava volcanoes, which erupt infrequently and spew hot lava and ash, mud volcanoes bubble almost constantly with warm or cool mud. The mud volcanoes of Azerbaijan vary greatly in size and shape. Many have small cones that produce rumbling noises and release gas, mud, and water. Many tourists visit Azerbaijan to view the unusual formations.
Mud volcanoes often form near underground oil or gas fields. The volcanoes are created when pressurized gas, mud, and water seep from deep beneath Earth’s surface. These deposits form mounds ranging from 16 feet (5 meters) to 1,640 feet (500 meters) high. Mud volcanoes occasionally have violent eruptions. In early 2001, the eruption of a mud volcano under the Caspian Sea created a new island, which has since washed away. In October 2001, Lokbatan, a mud volcano outside Baku, erupted and shot flames high into the air. Lokbatan has erupted more than 20 times since the early 1800’s. During some of the eruptions, flames briefly flared more than 1,000 feet (300 meters) into the air.