Causes of volcanic eruption and land-forms formed by lava

Discuss the causes of volcanic eruption and describe the land-forms formed by deposition of its lava.

Answer 

Volcanic eruption is one of the most powerful natural processes on Earth. It shapes continents builds islands and changes climate patterns across the world. Many students search for causes of volcanic eruption lava landforms types of volcanoes and volcanic activity in the Indian Ocean. This article explains in easy words the main causes of volcanic eruption and describes the important landforms formed by deposition of lava with special reference to the Indian Ocean region.Volcanic eruption happens when molten rock called magma rises from deep inside the Earth and reaches the surface. When magma comes out it is called lava. Along with lava gases ash and rock fragments are also released. The study of volcanoes is called volcanology.Volcanoes are mainly found along plate boundaries. The outer layer of the Earth is called the crust. It is divided into large pieces called tectonic plates. These plates are always moving slowly. The movement of tectonic plates is the most important cause of volcanic eruption.There are three main types of plate boundaries. Divergent boundaries convergent boundaries and transform boundaries. At divergent boundaries plates move away from each other. This creates a gap where magma rises to fill the space. This type of volcanic activity is common in mid ocean ridges like the Mid Atlantic Ridge in the Atlantic Ocean and also in the Indian Ocean.At convergent boundaries plates move towards each other. One plate may sink below the other in a process called subduction. The sinking plate melts due to high temperature and pressure. The melted material forms magma which rises and causes volcanic eruption. Many explosive volcanoes are formed at convergent boundaries. In the Indian Ocean region volcanic activity is seen near island arcs.Transform boundaries do not usually produce volcanoes because plates slide past each other without creating much magma. However the stress can sometimes lead to cracks through which magma escapes.Another important cause of volcanic eruption is the presence of hot spots. Hot spots are fixed areas in the mantle where temperature is very high. Magma rises from these hot spots and creates volcanoes even in the middle of a plate. A famous example in the Indian Ocean is the Reunion Island which was formed by hotspot volcanic activity.

Over time pressure builds up inside 

the magma chamber. Magma contains dissolved gases like water vapor carbon dioxide and sulfur dioxide. When pressure increases these gases expand. If the pressure becomes too high it leads to a sudden volcanic eruption. The type of eruption depends on the viscosity of magma. Viscosity means thickness. If magma is thick and sticky it traps gases and causes explosive eruptions. If magma is thin and fluid it flows easily and causes gentle eruptions.Basaltic lava is thin and flows over long distances. It forms shield volcanoes and lava plateaus. Rhyolitic lava is thick and forms steep sided volcanoes. Andesitic lava is of medium type and often leads to explosive eruptions.Earthquakes also play a role in volcanic eruption. Movement of tectonic plates creates cracks in the crust. These cracks allow magma to rise. Before an eruption small earthquakes are often recorded. Scientists use this information to predict volcanic activity.The Indian Ocean region is geologically active. The Indian Plate moves northward and collides with the Eurasian Plate. This movement has created mountain ranges and volcanic regions. The Andaman and Nicobar Islands are located in the Bay of Bengal and show volcanic activity. One of the active volcanoes in this region is the Barren Island which is the only active volcano in India.Volcanic eruption results in both destruction and creation. Lava that comes out during eruption cools and solidifies to form various landforms. These landforms formed by deposition of lava are very important in physical geography.One of the most common landforms formed by lava deposition is the shield volcano. Shield volcanoes have broad gentle slopes. They are formed by repeated flows of basaltic lava. Because the lava is fluid it spreads over large areas before cooling. These volcanoes look like a warrior shield lying on the ground. Reunion Island in the Indian Ocean is an example of a shield volcano.Another important landform is the composite volcano also known as stratovolcano. It is formed by layers of lava ash and rock fragments. 

volcanoes have steep slopes and cone shapes. 

They are usually formed at convergent plate boundaries. Though more common in the Pacific region some island arcs in the Indian Ocean show similar features.Lava plateau is a large flat area formed by successive flows of lava. When lava flows out from long cracks called fissures it spreads widely and cools into flat layers. Over time many layers build up and form a plateau. In India the Deccan Plateau was formed by massive volcanic eruptions millions of years ago. Though not directly in the Indian Ocean today it shows the power of fissure eruptions.Lava dome is another landform formed by thick lava. When viscous lava comes out slowly it piles up near the vent instead of flowing away. This creates a dome shaped structure. Lava domes are often found inside craters of composite volcanoes.Volcanic island is a landform formed when lava erupts under the ocean. As lava piles up it may rise above sea level and form an island. Many islands in the Indian Ocean were formed this way. The Maldives though mainly coral based are built on volcanic foundations deep under the sea.Seamounts are underwater volcanic mountains formed by lava deposition. If they grow tall enough they may become islands. Many seamounts are found in the Indian Ocean basin.Lava plains are wide flat areas formed by thin lava spreading over large regions. They are common in ocean floors. Mid ocean ridges including those in the Indian Ocean continuously create new oceanic crust through lava deposition.Another interesting feature formed by volcanic activity is the caldera. After a massive eruption the magma chamber may collapse and form a large depression. Though mainly associated with explosive eruptions the surrounding area is often covered with lava deposits.Black soil is another indirect result of volcanic lava. When lava rocks weather over time they form fertile soil rich in minerals. This soil supports agriculture. Many regions with past volcanic activity are highly fertile.Volcanic activity in the Indian Ocean has also contributed to the formation of island chains. The movement of the Indian Plate over hotspots created a series of islands and underwater ridges. This process explains the formation of Reunion Island and nearby island groups.Volcanic eruption also releases gases into the atmosphere. These gases can affect climate. Large eruptions may block sunlight and lower global temperatures for short periods. Ash from eruptions can travel long distances across oceans including the Indian Ocean region.Scientists monitor volcanic eruption using modern technology. They study seismic waves gas emissions ground deformation and temperature changes. Early warning systems help reduce damage and loss of life. In regions like the Andaman and Nicobar Islands monitoring is very important due to nearby tectonic activity.Volcanic eruption is both a destructive and creative force of nature. It destroys life and property but also creates new land fertile soil and valuable minerals. 

The causes of volcanic eruption 

are mainly tectonic plate movement hotspot activity pressure build up in magma chambers and gas expansion. The landforms formed by deposition of lava include shield volcano composite volcano lava plateau lava dome volcanic island seamount lava plains and caldera.The Indian Ocean region provides clear examples of volcanic processes. From Barren Island to Reunion Island volcanic activity continues to shape the ocean floor and islands. Understanding volcanic eruption and lava landforms is important for geography students competitive exams and disaster management studies. volcanic eruption is a natural process caused by internal heat and plate movement of the Earth. Lava deposition creates many important landforms that shape the surface of the Earth and the floor of the Indian Ocean. Study of volcanoes helps us understand Earth structure natural hazards and the formation of continents and islands. Volcanic activity remains a powerful reminder of the dynamic nature of our planet.