Tolbachik Volcano

Earth’s crust, or outer layer, is hard rock. But under the crust there are layers of softer rock and magma, rock so hot that it has melted. Volcanoes happen when heat pressure causes magma to rise up through the cracks in the crust and flow out onto Earth’s surface. 

This picture shows some of the physical elements that are part of volcanic eruptions.

Usually the first signs that a volcano is erupting are ground tremors and earthquakes. Next come feather-shaped clouds that rise out of vents, or openings, in the underlying rock. 

Volcanic clouds contain poisonous gases, such as carbon monoxide and sulfur dioxide, as well as carbon dioxide and steam. The steam comes from underground water that has been heated by the rising magma. 

Gases from active volcanoes can rise high into the atmosphere and affect air quality around the globe.

Magma that has emerged from under Earth’s surface is called lava. This melted rock is extremely hot. If the volcano explodes with enough power, the lava shoots high into the air. 

In shield volcanoes, such as Tolbachik, lava flows more gently, over the sides of the vent and across the ground. On the slopes below the volcano’s vent, we can see previous flows of lava that are now covered with snow.

In the most powerful eruptions, ash and cinders get blasted high into the air and rain down on the surrounding land. Ash deposits can cover hundreds of square miles. 

Ostry Tolbachik, Udina Bolshaya, and other stratovolcanoes have conical shapes because of the immense quantities of cinders and ash that they eject. The cinders and ash flow down in all directions, creating smooth, even sides. 

The Tolbachik volcano is located on the Kamchatka Peninsula, one of the most active volcanic zones on Earth. Hundreds of volcanic peaks provide evidence of the peninsula’s long and explosive geological history. The scientific theory that explains these volcanoes is called plate tectonics. 

Earth’s crust has many long cracks, or faults. The land areas between the cracks are called plates. One of Earth’s largest tectonic plates, the Pacific Plate, makes up the sea floor under the Pacific Ocean.

Down the middle of the Pacific Plate there is a chain of underwater volcanoes. As these volcanoes erupt, they build the land, and the Pacific Plate expands. 

The western side of the plate expands toward Asia (including the Kamchatka Peninsula). The eastern side of the plate expands toward North America (including Alaska).

Another very large tectonic plate, the Eurasian Plate, makes up the continents of Europe and Asia. The Kamchatka Peninsula is on the northeastern edge of the Eurasian Plate.

Just north of Kamchatka, the Eurasian Plate adjoins the North American plate. The Kamchatka Peninsula is volcanically active because it is located near where three tectonic plates join.

The Pacific Plate, under the Pacific Ocean, is gradually expanding in the direction of the Kamchatka Peninsula. When the edge of the Pacific Plate reaches the edge of the Eurasian Plate, the Pacific Plate sinks under the landmass of Asia. 

This process, which is called subduction, gradually lifts the Eurasian Plate, causing earthquakes and triggering volcanic activity.

 The “Ring of Fire” is the imaginative label used by scientists to describe the chain of active volcanoes that circle the Pacific Ocean. The volcanoes occur along the faults that separate Earth’s tectonic plates. 

The Pacific Plate, which lies under the Pacific Ocean, pushes against the tectonic plates that surround it: the Eurasian, Philippine, Indo-Australian, Antarctica, Nazca, Cocos, and North American Plates. 

There are volcanoes along all the fault lines, the edges where the plates meet. The entire Pacific Coast, on the continents of Asia, Australia, Antarctica, South America, and North America, is lined with volcanoes. Hundreds of these volcanoes are active.