Volcanic eruptions have a profound impact on the environment. Recently, these eruptions have made the headlines due to their catastrophic potential. Notably, in Japan, the famous Sakurajima Volcano and the Fukutoku-Okanoba Submarine Volcano erupted recently, causing significant concern.
Sakurajima Volcano: An Overview
Located on Japan’s major western island of Kyushu, Sakurajima is an active stratovolcano, notorious for frequent eruptions of varying intensity. The largest historical eruption events were recorded during 1471-76 and in 1914. Despite the danger it poses due to its explosive potential and regular ash deposition on Kagoshima, Sakurajima remains one of Japan’s most active volcanoes.
Decoding the Concept of Volcanoes
A volcano represents an opening on a planetary surface, allowing warmer interior material to escape. This could result in an explosive eruption, sending materials high into the sky, or a calmer event, with a gentle flow of material consisting of liquid rock (commonly known as “lava” on the surface and “magma” when underground), ash, cinders, and gas.
Tectonic Plates and Magma Rise
Magma rise is facilitated by the movement of Earth’s tectonic plates. When these plates move away from each other, magma rises to fill the space, potentially creating underwater volcanoes. Conversely, when the plates move toward each other, a part of the Earth’s crust can be forced deep into the core, with the increased heat and pressure causing the formation and rise of magma. Magma can also rise over hot spots, hot areas inside the Earth that reduce its density, facilitating its upward movement.
The Different Types of Volcanoes
Shield volcanoes are formed from low-viscosity, runny lava that spreads far from its source, resulting in a volcano with gentle slopes. Stratovolcanoes are more cone-shaped, have relatively steep sides and are formed from viscous, sticky lava. Then there are lava domes, large dome-shaped masses formed by extruded, viscous lava. Calderas are depressions or bowls with steep walls formed when a large eruption empties the magma chamber.
Indian Volcanoes: An Insight
India is home to several notable volcanoes. Barren Island, located in the Andaman Islands, is India’s only active volcano. Other volcanoes include Narcondam and Baratang in the Andaman Islands, Deccan Traps in Maharashtra, Dhinodhar Hills in Gujarat, and Dhosi Hill in Haryana. Barren Island is particularly important due to its active status; it has erupted at least five times in the past 100 years.
UPSC Civil Services Examination: Previous Year Questions
In the 2018 UPSC Civil Services Examination, a question was asked regarding the location of the Barren Island volcano, its distance from Great Nicobar, and its eruption history. Similarly, one of the mains questions in the 2021 examination pertained to the global occurrence of volcanic eruptions in 2021 and their regional environmental impact. These questions highlight the importance of having a comprehensive understanding of volcanoes and their related concepts for competitive exams.
