Indonesia experienced a series of volcanic eruptions from Mount Ruang, the southernmost stratovolcano situated in North Sulawesi Province in April 2024. Similarly, a new fissure eruption started on the Fagradalsfjall volcano in the Reykjanes Peninsula, Northeast from Sylingarfell Southwest Iceland in May 2024, marking the fifth eruption in the area since December 2023.
A volcano is a rupture or an opening on the top of the Earth’s crust (mountain) through which hot lava, volcanic ash, and gases escape on to the surface of the Earth. Volcanoes can be on land and in the ocean. They are associated with the tectonic plates that are diverging or converging resulting into volcanic eruption. Triggered by the movement of heat beneath the Earth’s surface, eruptions typically begin with gas-rich magma accumulation in reservoirs near the Earth’s crust. Sometimes, volcanic eruptions are preceded by emissions of steam and gas from small vents in the ground.
A stratovolcano is built up by many layers of hardened lava and tephra. They are characterised by a steep profile as compared to shield volcanoes. The lava emerging from stratovolcanoes cools and hardens before travelling far because of high viscosity.
Mount Ruang, one of the significant volcanic mountains in Indonesia, erupted for a second time in two weeks. The ash spread for two kilometres in the sky leading to the closure of a nearby airport. Mount Ruang, a 725m tall mountain in North Sulawesi province, is one of the 130 active volcanoes in Indonesia. The volcano has erupted at least 16 time since 1808 (first eruption).
Volcanic Eruption in Indonesia
Indonesia is a country situated off the coast of mainland Southeast Asia in the Indian and Pacific oceans. It is located on an archipelago which lies across the Equator, and covers one-eighth of the Earth’s circumference. The country consists of many islands grouped into Greater Sunda Islands of Sumatra, Java, Borneo, Celebs, Bali, the Moluccas, and New Guinea. Indonesia’s major islands are characterised by densely forested volcanic mountains.
Indonesia is susceptible to volcanic eruptions and earthquakes due to its location on the Pacific “Ring of Fire”, a series of fault lines which stretches from the America’s western coasts to Japan and Southeast Asia.
The Pacific Ring of Fire, also known as the Circum-Pacific Belt, is a region along the Pacific Ocean characterised by active volcanoes and frequent earthquakes. Its length is approximately 40,000 km. The ring consists of the boundaries of several tectonic plates, including the Pacific, Juan de Fuca, Cocos, Indian-Australian, Nazca, North American, and Philippine Plates. Over 450 of the Earth’s volcanoes (75 per cent of the total volcanoes) are located along the Ring of Fire. Ninety per cent of the Earth’s earthquakes occur along its path, including the most violent and dramatic seismic events on the planet.
Why Eruptions on the Ring of Fire
The Ring of Fire’s abundance of volcanoes and earthquakes is attributed to the movement of tectonic plates in the region. The region features subduction zones where plates overlap, with the underneath plate being subducted by the above plate. Rock subduction causes it to melt and transform into magma, creating conditions conducive to volcanic activity due to its proximity to the Earth’s surface. A significant exception is the border between the Pacific and North American Plates where the plates move sideways (transform boundary) instead of subduction. This sideway moving of plates leads to a significant number of earthquakes due to the accumulation and release of tension in the Earth’s crust.
In May 2024, Indonesian authorities reported a volcanic eruption on Mount Ibu also, located on the remote island of Halmahera, causing a grey ash cloud and evacuation of nearby villages. It released 2.5 miles of ash into the sky and caused flashes of purple lightning around its crater.
Volcanic eruption in Iceland occurred in May 2024 which marked the fifth eruption since December 2023. Here, eruption occurs on an average every five years. However, the frequency has become closer to every year since 2021. The area, known as Fagradalsfjall, some 35 km from the capital Reykjavik, came to life after a series of earthquakes shook the Reykjanes Peninsula. The three eruptions with months-long pauses signal the start of a new geological era on the southwestern peninsula, which has been dormant for some eight centuries.
Volcanic Eruption in Iceland
Iceland is an island nation situated in the North Atlantic Ocean on the dynamic geologic border between North America and Europe. Glacier ice and cooled lava cover about one-tenth of the country’s total area. Iceland is a relatively young geological country with approximately 200 distinct types of volcanoes. It is estimated that since the year 1500 CE, almost one-third of the Earth’s total lava flow has spilled out of Iceland’s volcanoes.
Why Eruptions in Iceland
Iceland’s is located on the Mid-Atlantic Ridge in the North Atlantic Ocean, which experiences movement of the Eurasian and North American plates. Since they are moving apart a few centimetres every year and cause the Earth’s crust to split and rip, volcanic rift zones are created where molten rock, or magma, rises to the surface and occasionally erupts as lava or ash. Besides, the region is situated over a hot zone (or hotspot, i.e., hot areas within the Earth where magma is heated up and as magma gets warmer, it becomes less dense, leading to its rise). This leads to the increased volcanic activity in the area.
Impact of Volcanic Eruptions
In general, volcanic eruptions pose several hazards like volcanic ash, gases, lahars, landslides, lava, flows, and pyroclastic flows. Lava is one of the health hazards and poses risks to life and property as molten rocks could cover houses, farms, and neighbourhoods and often causes population displacement. Sulphur-rich and other volcanic gases such as smog and vog also pose risks to health such as burning of eyes, headaches, and sore throats.
Volcano eruptions also result in landslides and mudslides, which are dangerous. However, the eruptions also provide a number of environmental benefits such as fertile soil, hydrothermal energy, precious minerals, and tourism.
Terms Related to Volcanic Eruption
Tephra are fragments of volcanic rock less than 2 millimetres to more than 1 metre in diameter that blast into the air during an explosive eruption.
Ash fall is a fine component of tephra that spreads over broad areas during an eruption. Ash particles can be hard, abrasive, and mildly corrosive. Freshly fallen ash can have an acidic coating that irritates eyes and lungs, and may pollute local water supplies and damage vegetation.
Lahar (mud or debris flows) is an Indonesian term which means hot or cold mixture of water and volcanic debris flowing down the slopes of volcano, and often entering a river valley. Lahars vary in size and speed and may be a few metres wide and several centimetres deep or hundreds of metres wide (up to 10 metres in diameter) and tens of metres deep.
Lava flows are streams of molten rocks that pour or ooze from an erupting vent. Fluid basalt flows can extend tens of kilometres and travel 1 kilometre per hour on gentle slopes and up to 10 kilometres per hour on steep slopes.
Volcanic gases released from a volcano include steam, carbon dioxide, sulphur dioxide, hydrogen chloride and hydrogen fluoride.
Pyroclastic flows and surges are high-density mixtures of hot, dry rock fragments and gases that move away from the vent at high speed. It consists of a basal layer of coarse fragments that move along the grounds and a more buoyant upper layer. This flow can deposit layers ranging from less than 1 metre to more than 200 metres.
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