Subject: Geographical Features

Why in the News?

Hunga Tonga-Hunga Ha’apai (Hunga Tonga) erupted in Tonga, triggering a tsunami and global seismic waves.

About Hunga Tonga Volcano

• The Hunga Tonga-Hunga Ha’apai volcano is situated in the western South Pacific Ocean, west of the main inhabited islands in the Kingdom of Tonga. It lies on the Pacific Ring of Fire.
• It forms part of the Tofua Arc, within the larger Tonga-Kermadec volcanic arc, resulting from the subduction of the Pacific Plate beneath the Indo-Australian Plate.
• It comprises two small uninhabited islands, Hunga-Ha’apai and Hunga-Tonga.
• Hunga Tonga is one of 12 confirmed submarine volcanoes along the Tofua Arc.

Key Findings on Hunga Tonga Eruption

• The Hunga Tonga eruption primarily emitted water vapour, which reached the stratosphere, affecting ozone depletion and acting as a potent greenhouse gas. Minimal smoke was produced.

Impact on Weather

• Ozone Hole: The study reveals that Hunga Tonga contributed to the exceptionally large ozone hole in the preceding year and the unexpectedly wet summer of 2024.
• Global Mean Temperatures: While the eruption had a negligible effect on global temperatures, it induced lasting regional disruptions in atmospheric wave patterns.
  • Traditionally, massive volcanic eruptions reduce temperatures by emitting sulfur dioxide, which forms sulphate aerosols reflecting sunlight.
• Regional Effects: Anticipated changes include colder and wet winters in northern Australia, warmer winters in North America, and colder winters in Scandinavia until approximately 2029.

Do you know? Previous volcanic eruptions, such as Tambora in 1815 and Samalas in 1257, have significantly impacted global climate, leading to phenomena like the “year without a summer” and the onset of the Little Ice Age.

 

PYQ: [2021] Discuss about the vulnerability of India to earthquake-related hazards. Give examples including the salient features of major disasters caused by earthquakes in different parts of India during the last three decades.

Why in the News?

Southwest Iceland witnessed the eruption of the Sundhnuksgigar volcano, triggering evacuations in the nearby areas.

About Sundhnuksgigar Volcano 

• Sundhnuksgigar is a row of craters just outside the town of Grindavik on the Reykjanes peninsula
• It is situated on the Mid-Atlantic Ridge, a divergent boundary where the Eurasian and North American tectonic plates are moving apart.

What is a Volcano? A volcano is a fissure or vent in the Earth’s crust through which gases, molten rock materials (lava), ash, steam, sulphur dioxide etc., are expelled during an eruption. These openings occur where the rock layers in the Earth’s crust are relatively weak. Volcanic activity is categorized as an endogenic process, originating from within the Earth. Depending on the explosivity of the volcano, various extrusive and intrusive landforms can be formed. Different types of volcanoes can be classified based on the frequency of eruption and the nature of the eruption: 1.   Frequency of eruption: Active volcanoes: Frequent eruptions in Pacific Ring of Fire: New Zealand, Southeast Asia, Japan, western Americas. Linked to plate tectonics, like Kilauea and Santa Maria. High seismicity, volcanic activity. Dormant Volcanoes: These are not currently erupting but have the potential to erupt again in the future. An example is Mount Kilimanjaro in Tanzania, the highest mountain in Africa. Extinct or inactive volcanoes: These have not erupted in the distant geological past. Dhinodhar Hill in Gujarat is an example. 2.   Nature of Eruption: Shield Volcanoes: Largest and least explosive volcanoes, formed from basalt lava. Often low in explosivity, except when water interacts. Hawaiian volcanoes exemplify this.. Composite Volcanoes: Volcanoes with cooler, thicker lava, built up through explosive eruptions. Layer ash, pyroclastic material, and lava flow. Examples: Mayon, Fuji, Rainier. Calderas: The most explosive volcanoes, prone to collapsing inward during eruptions rather than building upwards. The resulting depressions are called calderas. Flood Basalt Provinces: These volcanoes erupt highly fluid lava that travels long distances, covering vast areas with thick basalt flows.

Reasons for Iceland’s Volcanism

• Tectonic Activity: Iceland is situated on the Mid-Atlantic Ridge, where the Eurasian and North American plates diverge. This creates volcanic rift zones where magma rises to the surface, leading to eruptions.
• Hotspots: Additionally, Iceland is positioned over a hotspot, contributing to heightened volcanic activity. Hotspots are areas where magma from the mantle rises towards the surface, fueling eruptions.
• Subglacial Volcanism: Iceland’s volcanic activity is not limited to the surface; some eruptions occur beneath glaciers, leading to explosive interactions between lava and ice. These subglacial eruptions can produce powerful steam explosions, ash clouds, and catastrophic floods known as jokulhlaup.

PYQ: [2021] Mention the global occurrence of volcanic eruptions in 2021 and their impact on the regional environment. [2013] Consider the following: Electromagnetic radiation Geothermal energy Gravitational force Plate movements Rotation of the earth Revolution of the earth Which of the above are responsible for bringing dynamic changes on the surface of the earth? (a) 1, 2, 3 and 4 only (b) 1, 3, 5 and 6 only (c) 2, 4, 5 and 6 only (d) 1, 2, 3, 4, 5 and 6

Why in the News?

The National Green Tribunal (NGT) has directed the State Environment Impact Assessment Authority (SEIAA) and the mines and geology department to stop any unlawful/illegal sand mining in the Sharavathi River coastal zone.

About National Green Tribunal (NGT)

	Description
Establishment	Formed in 2010 under the National Green Tribunal Act as a statutory body.
Objective	To deal with cases related to environmental issues and ensure speedy implementation of decisions. Responsible for giving many prominent decisions aimed at environmental protection, including addressing air pollution in Delhi and canceling coal block clearances.
Composition	Headquartered in Delhi, chaired by a retired Supreme Court judge Included Judicial Members and Expert Panel.
Powers	Empowered to decide on questions related to various environmental laws and hear civil cases concerning environmental issues: The Water (Prevention and Control of Pollution) Act, 1974; The Water (Prevention and Control of Pollution) Cess Act, 1977; The Forest (Conservation) Act, 1980; The Air (Prevention and Control of Pollution) Act, 1981; The Environment (Protection) Act, 1986; The Public Liability Insurance Act, 1991; The Biological Diversity Act, 2002.
Exceptions	Prohibited to hear any issues which are covered under: The Indian Forest Act, 1927, The Wildlife (Protection) Act, 1972, and Any other laws made by States which are related to protection of trees, forests, etc.
Places	Principal bench in Delhi; Additional benches in Bhopal, Pune, Kolkata, and Chennai.
Governing Principles	Governed by principles of natural justice, not bound by Indian Evidence Act. Applies principles of sustainable development, precautionary, and polluter pays.
Review and Challenge	NGT orders can be reviewed as per Rule 22 of NGT Rules. Can be challenged before the Supreme Court within 90 days.
Jurisdiction	Jurisdiction over all civil cases involving a substantial question relating to environment. Powers vested are the same as in a civil court under the Code of Civil Procedure, 1908. Decisions are binding.
Disposal of Cases	Disposal of applications or appeals finally within 6 months of filing of the same.

About Sharavathi River

• It originates and flows entirely within Karnataka.
• It is among the few westward-flowing rivers in the country and a significant part of its basin lies in the Western Ghats.

• Origin: The river originates at Ambutheertha in the Thirthahalli taluk.
• Legend: According to ancient legend, the god Rama shot an arrow (Ambu) into the ground to quench his wife Sita’s thirst. The water that poured out was named “Thirtha,” hence the river’s name “Sharavati,” with “Shara” meaning arrow.

Geography and Length:

• The river stretches about 128 km (80 mi) and joins the Arabian Sea at Honnavar in Uttara Kannada district.
• Jog Falls, formed by the Sharavati River, is located approximately 25 km from Siddapura.

Tributaries and Basin:

• Major tributaries: Nandihole, Haridravathi, Mavinahole, Hilkunji, Yennehole, Hurlihole, and Nagodihole.
• River basin: divided between Uttara Kannada and Shimoga districts.
• Pre-Cambrian rocks, including the Dharwar system and peninsular gneiss, dominate the basin.

Soils and Agriculture:

• Soils in the basin are predominantly lateritic and tend to be acidic, ranging from clay loamy to loamy.
• Four soil orders are found: ultisols, alfisols, inceptisols, and entisols.

Dams:

• The Linganamakki Dam, constructed in 1964, spans the Sharavati River, with a catchment area of nearly 1,991.71 km2.
• The Gerusoppa Dam, completed in 2002, primarily serves for electricity generation.

Flora and Fauna:

• The Sharavati Valley Wildlife Sanctuary declared in 1972, protects diverse ecosystems and endangered species.
• The river basin is rich in biodiversity, home to rare species of flora and fauna.

Regulation of Sand Mining in India: Mines and Minerals Act, 1957 Definition of Sand as a Minor Mineral Sand is categorized as a minor mineral under section 3(e) of the MMDR Act. State Governments’ Role Section 15 empowers state governments to regulate mineral concessions for minor minerals, leading to the formulation of state-specific concession rules. Control of Illegal Mining Section 23C places the jurisdiction over controlling illegal mining under the purview of state governments. Sustainable Sand Mining Management Guidelines, 2016 Purpose Released by the Ministry of Environment, Forest and Climate Change, aims to promote scientific and environmentally friendly sand mining practices. Recommendations Emphasizes sustainable sand extraction, monitoring, and district-wise mapping of sand availability. Sand Mining Framework, 2018 Issued by Released by the Ministry of Mines, provides states with guidance for policy formulation and combating illegal sand mining. Recommended Measures Suggests geo-fencing, GPS-enabled transportation tracking, price control, involvement of women’s self-help groups, and exploration of alternative sand sources.

 

PYQ: [2018] Which of the following is/are the possible consequence/s of heavy sand mining in riverbeds? Decreased salinity in the river Pollution of groundwater Lowering of the water-table Select the correct answer using the code given below: (a) 1 only (b) 2 and 3 only (c) 1 and 3 only (d) 1, 2 and 3 [2019] With reference to the management of minor minerals in India, consider the following statements : Sand is a ‘minor mineral’ according to the prevailing law in the country. State governments have the power to grant mining leases of minor minerals, but the powers regarding the formation of rules related to the grant of minor minerals lie with the Central Government. State Governments have the power to frame rules to prevent illegal mining of minor minerals. Which of the statements given above is/are correct? (a) 1 and 3 only (b) 2 and 3 only (c) 3 only (d) 1, 2 and 3

Why in the News?

Incidences of people drowning down into the Mahi River have become more frequent.

About Mahi River

• The Mahi River originates in the Vindhya Range of Madhya Pradesh (hot semi-arid and watershed region), near Dhar.
• It flows northward through Madhya Pradesh before turning westward upon entering Rajasthan. It then moves southwest, passing through Gujarat, and eventually empties into the Arabian Sea.
• The river stretches for about 580 kilometers.
  • Soil Type: The Mahi River Basin consists of Deep Black soil (southern region) and Alluvial soil (northern region).
  • Major Tributaries: the Som, the Anas, the Panam, and the Goma.
  • Major Dams: Kadana Dam and the Mahi Bajaj Sagar (Banswara) Dam are significant hydroelectric and irrigation projects on the Mahi River.
  • Biodiversity: Supports diverse flora and fauna, including endangered species like the Indian Skimmer and Gharial.

Key Features:

• It is surrounded by the Aravalli Hills to the north and northwest, the Malwa Plateau to the east, the Vindhyas to the south, and the Gulf of Khambhat to the west.
• One of the most notable features of the Mahi River is its crossing of the Tropic of Cancer twice; once in Madhya Pradesh and again near the Gujarat-Rajasthan border.

PYQ: [2017] With reference to river Teesta, consider the following statements: 1. The source of river Teesta is the same as that of Brahmaputra but it flows through Sikkim. 2. River Rangeet originates in Sikkim and it is a tributary of river Teesta. 3. River Teesta falls into Bay of Bengal at the border of India and Bangladesh. Which of the statements given above is/are correct? (a) 1 and 3 only (b) 2 only (c) 2 and 3 only (d) 1, 2 and 3

With inputs from: https://indiawris.gov.in/downloads/Mahi%20Basin.pdf

Why in the news?

• In a rare event, the night sky over Hanle village in Ladakh was illuminated by the northern lights or aurora borealis.
  • Concurrently, the southern lights, or aurora australis, were observed in New Zealand and Australia.

What are Auroras?

• Auroras are natural light displays that appear as bright, swirling curtains in the night sky.
• They are typically seen near the Poles but can occasionally be observed at lower latitudes.
• These lights can display a range of colors, including blue, red, yellow, green, and orange, due to the interaction of solar particles with different gases in the Earth’s atmosphere.
• The phenomenon is known as:

1. Aurora borealis in Northern Hemisphere and
2. Aurora australis in Southern Hemisphere

What causes Auroras?

• Interaction with Earth’s Magnetic Field: As the solar wind approaches Earth, it interacts with the planet’s magnetic field, causing some charged particles to enter the atmosphere near the poles.
• Interaction with Gases: These particles interact with gases in the upper atmosphere, producing colourful flashes of light. Collision with oxygen produces green light, while interaction with nitrogen results in shades of blue and purple.

Reasons for Aurora in Ladakh: Intense Solar Activity: Auroras can extend to lower latitudes during periods of intense solar activity, such as solar flares and coronal mass ejections (CMEs). The CMEs are from the AR13664 region of the sun that has produced several high-energy solar flares Localized magnetic anomalies: Variations in Earth’s magnetic field could potentially influence the occurrence of auroras in specific areas, including regions at lower latitudes.

Impact on Tech Infrastructure 

• Auroras can pose challenges to space-dependent technologies and operations.
• Disruptions in Global Positioning Systems (GPS), radio communications, flight operations, power grids, and space exploration endeavors may occur during such events.

PYQ: [2022] If a major solar storm (solar flare) reaches the Earth, which of the following are the possible effects on the Earth? GPS and navigation systems could fail. Tsunamis could occur at equatorial regions. Power grids could be damaged. Intense auroras could occur over much of the Earth. Forest fires could take place over much of the planet. Orbits of the satellites could be disturbed. Shortwave radio communication of the aircraft flying over Polar Regions could be interrupted. Select the correct answer using the code given below: (a) 1, 2, 4 and 5 only (b) 2, 3, 5, 6 and 7 only (c) 1, 3, 4, 6 and 7 only (d) 1, 2, 3, 4, 5, 6 and 7

 

Why in the news?

• The Eta Aquariid meteor shower, an annual event, will reach its peak on May 5 and 6.
• This meteor shower is a result of Earth intersecting with the debris trail left by Halley’s Comet during its orbit.

Halley’s Comet Halley’s Comet is a short-period comet visible from Earth every 75–79 years. It was last seen in Earth’s skies in 1986 and was met in space by an international fleet of spacecraft. It will return in 2061 on its regular journey around the Sun.

What are Meteoric Showers?

• Meteors, fragments of dust, rock and ice, are expelled from comets during their celestial orbits around the sun.
• The Earth’s atmosphere heats these space rocks as they descend, leaving luminous streaks of gas in their way.
• NASA’s records confirms existence of over 30 meteor showers annually.

Origin of Meteor Showers:

• Meteor showers originate from comets, remnants of the solar system’s formation composed of dust, rock, and ice.
• Comets orbit the Sun in highly elliptical paths, and as they approach, they heat up, releasing gases and dust to form a glowing head and a tail stretching millions of miles.
• When Earth traverses through the debris left behind by comets along their orbital plane, we witness meteor showers.

About Eta Aquariids

• Known for their rapid speed, Eta Aquariid meteors produce long, glowing tails lasting several minutes.
• Observers in the Southern Hemisphere can witness approximately 30 to 40 meteors per hour during the peak, while those in the Northern Hemisphere may see around 10 meteors per hour.
• They seem to originate from the Aquarius constellation, hence the name ‘Eta Aquariid.’

PYQ: [2014] What is a coma, in the content of astronomy? (a) Bright half of material on the comet (b) Long tail of dust (c) Two asteroids orbiting each other (d) Two planets orbiting each other