Sector collapse

A sector collapse is when a large piece of a volcano breaks off and falls down very quickly. This piece can be as big as one cubic kilometer, about the size of a small mountain. When this happens, it can cause powerful sideways explosions, big landslides, and changes in how the volcano erupts. These collapses can be triggered by earthquakes, volcanic eruptions, or slow changes in the shape of the volcano over time.

Sector collapses can happen on volcanoes where Earth's plates come together or move apart. Even though they happen suddenly, scientists are working to find ways to predict them. These events are very dangerous and are one of the biggest risks with volcanoes. Learning more about them helps scientists keep people near active volcanoes safe.

Causes

Sector collapse can happen because of things happening inside a volcano. When a volcano erupts, it can weaken parts of the volcano, causing them to fall down. Even without an eruption, movements inside the volcano, like magma shifting or cracks forming, can make the volcano weaker and lead to collapse. The shape and angle of the volcano matter too—if the slope gets too steep, it can collapse under its own weight.

Outside factors can also cause sector collapse. Earthquakes can shake a volcano and make it weaker. Heavy rain and strong weather can wear away the rock, making the volcano unstable. When glaciers melt, they can change the shape of a volcano and make collapse more likely. Changes in sea level can also affect the stability of volcanoes near the ocean.

Consequences

When a big part of a volcano collapses, it can change how the volcano behaves. Sometimes, the volcano may erupt more often after the collapse. The collapse can also cause sudden explosions of steam and water.

These events can be very dangerous for people. They have destroyed homes and made it hard for people to stay safe. One famous collapse created a big wave in the ocean that reached coastal areas. Scientists study the rocks and land left behind to learn about past collapses. These rocks give clues about when and where the collapse happened.

Examples

Some famous examples of sector collapses include volcanoes like Antuco, Chimborazo, Popocatépetl, Mount Rainier, Mount Shasta, Shiveluch, and Stromboli. More recent events happened at Anak Krakatoa, Mount Bandai, Bezymianny, Oshima-Oshima, Ritter Island, and Mount St. Helens. These examples show how powerful volcanic collapses can be.