Causes of Volcanic Eruption and Landforms Formed by Lava Deposition

Causes of Volcanic Eruption

1. Tectonic Plate Movements: The most common cause of volcanic eruptions is the movement of tectonic plates. Volcanic activity often occurs at plate boundaries—either convergent (where plates collide) or divergent (where plates pull apart). For example, the Ring of Fire around the Pacific Ocean is a zone of intense volcanic activity due to such tectonic movements.
2. Magma Pressure: Volcanic eruptions occur when magma (molten rock) from the Earth’s mantle rises through the crust due to pressure. This pressure can build up in magma chambers beneath the surface, leading to explosive eruptions. The 2021 eruption of La Palma in the Canary Islands was partly due to the build-up of magma pressure.
3. Gas Accumulation: Volcanic eruptions can also be triggered by the accumulation of gases like carbon dioxide, sulfur dioxide, and steam within the magma. When these gases reach a critical pressure, they can cause violent explosions. The Mount St. Helens eruption in 1980 was a result of such gas accumulation.

Landforms Created by Lava Deposition

1. Shield Volcanoes: Formed by the flow of low-viscosity basaltic lava, shield volcanoes have broad, gentle slopes. The Hawaiian Islands, including Mauna Loa and Kilauea, are classic examples of shield volcanoes created by continuous lava flows.
2. Composite Volcanoes (Stratovolcanoes): These are characterized by steep, conical profiles formed from alternating layers of lava flows, volcanic ash, and rock debris. Mount Fuji in Japan and Mount Vesuvius in Italy are examples of composite volcanoes.
3. Lava Plateaus: Extensive lava flows spread over large areas can create lava plateaus with flat, expansive surfaces. The Deccan Plateau in India is a significant example of a lava plateau formed by extensive volcanic activity.
4. Cinder Cones: These are small, steep-sided volcanoes built up from volcanic debris like ash and cinders ejected during eruptions. Paricutin in Mexico is a notable example of a cinder cone.

Recent Examples

• The 2020-2021 eruption of Mount Etna in Italy has contributed to both new land formations and modified existing ones through continuous lava flows and ash deposits.
• The Icelandic eruption at Geldingadalir in 2021 created new landforms with its continuous lava flows, demonstrating the dynamic nature of volcanic landscapes.

In summary, volcanic eruptions are caused by tectonic movements, magma pressure, and gas accumulation, and they create a variety of landforms, including shield volcanoes, composite volcanoes, lava plateaus, and cinder cones, each contributing uniquely to the Earth’s topography.