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Subject: Geography

  • Indonesia’s Mount Lewotobi erupts

    Why in the News?

    Mount Lewotobi Laki Laki in eastern Indonesia has erupted violently, spreading ash up to 18 kilometers into the sky.

    About Mount Lewotobi: Key Features

    • Overview: Mount Lewotobi is a twin volcano located in East Nusa Tenggara province, consisting of Lewotobi Laki Laki (“Male”) and Lewotobi Perempuan (“Female”).
    • Elevation and Activity: Lewotobi Laki Laki stands at 1,584 meters and is more frequently active. Lewotobi Perempuan is taller at 1,703 meters but less active historically.
    • Volcanic Type: Both mountains are stratovolcanoes, formed by successive layers of lava, ash, and volcanic debris.
    • Lava Domes: During the 20th century, both volcanoes developed small lava domes within their summit craters.
    • Magma Composition: The primary eruptive material from both volcanoes is andesite, a type of intermediate volcanic rock.
    • Tectonic Location: The volcanoes lie on the Pacific Ring of Fire, a seismically active belt known for frequent earthquakes and volcanic eruptions.

    Back2Basics: The Pacific Ring of Fire

    • Overview: The Pacific Ring of Fire is a 40,000-km-long horseshoe-shaped zone encircling much of the Pacific Ocean, known for intense geological activity.
    • Volcanic Density: This region contains around 75 percent of the world’s volcanoes—more than 450 in total.
    • Seismic Activity: Approximately 90 percent of the world’s earthquakes occur within this zone.
    • Geographic Spread: It extends from New Zealand through Indonesia, the Philippines, and Japan, across to the Aleutian Islands, and then down the western coasts of North and South America.
    • Tectonic Plates Involved: Several major tectonic plates intersect here, including the Pacific, Philippine, Juan de Fuca, Cocos, Nazca, and North American plates.
    • Subduction Zones: Much of the Ring features subduction zones, where one tectonic plate slides beneath another, generating magma and leading to volcanic eruptions.
    • Plate Movement: The movement of these plates is slow—typically just one to two inches per year—but it results in significant geological events over time.

     

    [UPSC 2018] Consider the following statements:

    1. The Barren Island volcano is an active volcano located in the Indian territory.

    2. Barren Island lies about 140 km east of Great Nicobar.

    3. The last time the Barren Island volcano erupted was in 1991 and it has remained inactive since then. Which of the statements given above is/are correct?

    Options: (a) 1 only (b) 2 and 3 (c) 3 only (d) 1 and 3

     

  • 1000 quakes rattle Japan’s Tokara Islands

    Why in the News?

    Japan has recorded over 1,000 tremors in two weeks near the Tokara Islands, signalling a surge in seismic activity.

    Why is Japan so prone to earthquakes?

    • Tectonic Plate Convergence: Japan lies at the junction of four major tectonic plates—the Pacific, Philippine Sea, Eurasian, and North American—which constantly collide and shift.
    • Subduction Zones: Oceanic plates (Pacific and Philippine Sea) are being pushed under continental plates, creating intense geological stress that is released as earthquakes.
    • Pacific Ring of Fire: Japan is part of this highly active seismic zone that surrounds the Pacific Ocean and accounts for about 90% of the world’s earthquakes.
    • Volcanic and Fault Line Density: The country has about 10% of the world’s active volcanoes and numerous fault lines, increasing its seismic vulnerability.

    About Tokara Islands:

    • Overview: They are a small volcanic island chain in the Ryukyu archipelago, forming part of Kagoshima Prefecture in southern Japan:
    • Geographical Location: Between Kyushu and the Amami Islands, in the East China Sea.
    • Composition: Includes 12 islands, of which 7 are inhabited, such as Nakanoshima, Takarajima, and Kodakarajima.
    • Volcanic Origin: Part of the Ryukyu Arc, a highly seismically active zone. Mount Otake, an active volcano, is located on Nakanoshima.
    • Geopolitical Relevance: The islands are gaining strategic significance due to rising tensions in the East China Sea, particularly involving China and Taiwan. Recent defense policies have called for fortification of the Tokara and Nansei Islands to enhance surveillance.
    [UPSC 2008] In the year 2007, an earthquake led to massive radioactive water leakage in the largest nuclear plant in the world. In which country did it occur?

    Options: (a) Germany (b) Canada (c) Japan* (d) USA

     

  • In news: Seine River

    Why in the News?

    French authorities have opened up the Seine River to public swimming for the very first time since 1923.

    In news: Seine River

    About the Seine River:

    • Overview: it is a major waterway in northern France, flowing through some of the country’s most important cultural and economic regions.
    • Length and Rank: It is approximately 777 km(483 miles) long, making it the second-longest river in France after the Loire.
    • Source and Elevation: It originates from the Langres Plateau in the Burgundy region, near the town of Source-Seine, at an elevation of about 444–471 meters above sea level.
    • Course Through France: It flows northwest, passing through regions such as Burgundy, Champagne, and Île-de-France, and cities like Troyes, Melun, Corbeil, and Paris.
    • Path Through Paris: In Paris, the Seine winds through the city center for about 13 kilometers, forming the famous islands Île de la Cité and Île Saint-Louis.
    • Tributaries: It is joined by several important tributaries, including the Marne, Yonne, Aube, and Oise rivers.
    • Drainage Basin and Rainfall: Its drainage basin spans 76,000–79,000 square kilometers, receiving moderate rainfall of 650–750 mm annually, and covering much of northern France.
    • Mouth and Termination: The river empties into the English Channel between Le Havre and Honfleur, on the Normandy coast.
    • Economic Role: The Seine supports commercial navigation and shipping, especially through the ports of Rouen and Le Havre, and provides about 50% of Paris’s drinking water.
    [UPSC 2020] Consider the following pairs: River Flows into

    1. Mekong Andaman Sea 2. Thames Irish Sea 3. Volga Caspian Sea 4. Zambezi Indian Ocean Which of the pairs given above is/are correctly matched?

    Options: (a) 1 and 2 only (b) 3 only (c) 3 and 4 only* (d) 1, 2 and 4 only

     

  • How India ‘added’ more than 3,500 km to its coastline

    Why in the News?

    India’s coastline has increased by about 48%, not because of new land but due to better digital mapping and updated measurements. It has grown from 7,516 km to 11,098 km, giving a clearer view of the country’s natural borders.

    What led to the increase in India’s measured coastline length?

    • Use of High-Resolution Mapping Technology: The shift from low-resolution (1:4,500,000) to high-resolution data (1:250,000) allowed finer measurement of the coastline’s bends and curves. Eg: Modern GIS software captured intricate coastal shapes that older manual methods missed.
    • Inclusion of Previously Omitted Offshore Islands: Many small offshore islands that were earlier not visible or excluded due to manual limitations are now included. Eg: Several minor islands around the Andaman & Nicobar and Lakshadweep regions added extra coastline length.
    • Coastline Paradox and Irregularity of Landforms: Coastlines are naturally irregular; measuring them at a finer scale captures more detail, thus increasing total length. Eg: Like using a one-meter ruler instead of a one-kilometre one—more small features are counted, increasing overall length.

    Why is the coastline paradox relevant to India’s coastal mapping?

    • Scale-Dependent Measurement: The coastline paradox shows that a coastline’s length varies based on the scale or resolution used for measurement—the finer the scale, the longer the coastline appears. Eg: Measuring with 1:250,000 scale data gives a much longer length than with 1:4,500,000 scale data.
    • Irregular Nature of Coastlines: Coastlines are highly irregular, full of bends, curves, and inlets, which get missed at lower resolutions but captured at higher ones. Eg: A low-resolution map smooths out land features, while high-resolution GIS tools map every minor curve.
    • No Fixed Length: The paradox proves that coastlines do not have a finite length—they can always be measured in more detail, leading to ever-changing figures. Eg: Even with current high-tech tools, the actual coastline length keeps increasing with better precision in future reassessments.

    How does reassessing the coastline and islands impact governance and security?

    • Accurate Administrative and Developmental Planning: Reassessment provides a clear understanding of territorial boundaries, aiding in efficient governance and infrastructure development. Eg: Updated coastline data helps plan coastal roads, ports, and disaster response systems in states like Gujarat and West Bengal.
    • Strengthening Maritime Security and Surveillance: Precise mapping helps in identifying vulnerable points, enabling better deployment of naval and coast guard resources. Eg: Mapping of remote islands assists in setting up radar stations and surveillance posts in regions like Lakshadweepand Andaman & Nicobar.
    • Strategic Assertion and Environmental Management: Helps in asserting sovereignty over maritime zones and managing coastal ecosystems more effectively. Eg: Reassessment supports India’s claim over its Exclusive Economic Zone (EEZ) and strengthens climate resilienceplanning in coastal areas.

    What challenges exist in accurately counting India’s offshore islands?

    • Ambiguity in Definitions and Tidal Variations: Some landforms may appear as islands during high tide but get connected to the mainland during low tide, causing confusion in classification. Eg: Certain coastal features in Sundarbans and Gulf of Khambhat shift between island and non-island status based on tide levels.
    • Discrepancies Across Agencies and Lack of Standardisation: Different agencies like state governments, Coast Guard, and Surveyor General have reported varying island countsdue to inconsistent definitions and methods. Eg: In 2016, the Surveyor General listed 1,382 islands, while other agencies reported 1,334, leading to a need for data reconciliation.

    Way forward: 

    • Standardised Methodology and Regular Reassessment: Adopt a uniform classification system for islands and coastlines across all agencies, and institutionalise periodic reassessments using high-resolution GIS and satellite data every 10 years.
    • Integrated Coastal Management and Strategic Mapping: Develop a centralised coastal database linking administrative, ecological, and security data to support policy-making, climate resilience, and maritime defence planning.

    Mains PYQ:

    [UPSC 2024] In a crucial domain like the public healthcare system, the Indian State should play a vital role to contain the adverse impact of marketisation of the system. Suggest some measures through which the State can enhance the reach of public health care at the grassroots level.

    Linkage: This article explicitly highlights alcohol consumption as a significant public health issue in India, leading to injuries, mental illness, non-communicable diseases like cancer, and contributing to approximately 2.6 million Disability-Adjusted Life Years (DALYs) in 2021.

  • Legal mandate for One Nation, One Time 

    Why in the News?

    The Government of India has mandated the use of Indian Standard Time (IST) across all legal, commercial, digital, and administrative sectors.

    About Indian Standard Time (IST):

    • It is the official time zone of India, set at Coordinated Universal Time (UTC) +5:30 and based on the 82.5° E longitude passing through Mirzapur, Uttar Pradesh.
      • Neighbouring countries such as Sri Lanka also use the same UTC+5:30 offset.
    • IST meridian passes through 5 Indian states: Uttar Pradesh, Madhya Pradesh, Chhattisgarh, Odisha, and Andhra Pradesh.
    • It was established in 1906, replacing older regional time zones like Bombay, Calcutta, and Madras Time.
    • It is maintained by the National Physical Laboratory (CSIR-NPL) using ultra-precise atomic clocks, which lose only one second in millions of years.
    • India does NOT observe daylight saving time; IST remains constant throughout the year.

    Back2Basics:

    Greenwich Mean Time (GMT):

    • GMT is the mean solar time at the Prime Meridian (0° longitude) located at the Royal Observatory in Greenwich, London.
    • It was established in 1884 during the International Meridian Conference as the world’s time standard.
    • It is based on astronomical observations, specifically the mean position of the Sun over time.
    • It does not change with the seasons and does not observe Daylight Saving Time (DST).
    • Although now largely replaced by UTC in scientific and civil contexts, GMT is still used in some regions (e.g., the UK during winter months).

    Coordinated Universal Time (UTC):

    • UTC is the primary time standard by which the world regulates clocks and time.
    • It was established in 1960 and is maintained by a network of high-precision atomic clocks worldwide.
    • UTC is adjusted periodically by leap seconds to compensate for the Earth’s irregular rotation speed.
    • It is used in aviation, computing, space science, and by international organisations like the UN and ITU.
    • Unlike GMT, which is purely solar-based, UTC combines atomic time (TAI) with occasional corrections for Earth’s rotation.

    IST in Context:

    • IST = GMT + 5:30
    • IST = UTC + 5:30

     

    Steps to Implement One Nation, One Time:

    [1] Time Dissemination Project:

    • It is a government initiative to ensure accurate, synchronised, and secure timekeeping across India.
    • It is led by the Department of Consumer Affairs, in collaboration with CSIR-NPL and ISRO.
    • Five Regional Reference Standard Laboratories (RRSLs) are being established in Ahmedabad, Bengaluru, Bhubaneswar, Faridabad, and Guwahati.
    • These labs use atomic clocks and protocols like Network Time Protocol (NTP) and Precision Time Protocol (PTP) to maintain accuracy within microseconds.

    [2] Legal Metrology (IST) Rules, 2025: Key Provisions

    • Mandatory Use of IST: IST, as maintained by CSIR-NPL, becomes the sole legally recognized time standard in India.
    • Prohibition of Foreign Time Sources: Use of foreign systems like GPS time will be banned unless specifically approved by the government.
    • Sync Requirements: All government bodies, financial institutions, power grids, and telecom operators must synchronize their systems with IST.
    • Audit and Compliance: The system will be monitored through periodic audits and penalties will be imposed for violations.
    • Special Exemptions: Activities such as scientific research, astronomy, and national security operations may use alternative time sources after government approval.

     

    [UPSC 2025] Consider the following countries:

    I. United Kingdom II. Denmark III. New Zealand IV. Australia V. Brazil How many of the above countries have more than four time zones?

    (a) All the five (b) Only four * (c) Only three (d) Only two

     

  • [pib] Ancient Assam Fossils Link to Western Ghats Biodiversity 

    Why in the News?

    In Assam’s Makum Coalfield, BSIP scientists found 24–23 million-year-old fossil leaves resembling today’s Nothopegia, now limited to the Western Ghats.

    [pib] Ancient Assam Fossils Link to Western Ghats Biodiversity 

    About the Nothopegia Fossil Discovery

    • Overview: Palaeo-scientists from Lucknow discovered fossil leaves in the Makum Coalfield of Assam. It dates back 24–23 million years to the late Oligocene epoch.
    • Oldest Known Record: These are the oldest known fossils of the Nothopegia genus, a tropical plant now endemic to the Western Ghats, not found in Northeast India today.
    • Identification Methods: Researchers used morphological analysis, herbarium comparisons, and cluster analysis to identify the fossil leaves.
    • Tropical Legacy: Nothopegia belongs to the Anacardiaceae family and reflects ancient tropical ecosystems that once existed in Northeast India.
    • Climate Reconstruction: Using the Climate Leaf Analysis Multivariate Program (CLAMP), scientists confirmed that the region once had a warm and humid climate, similar to the present-day Western Ghats.

    Why did Nothopegia disappear from the Northeast?

    • Tectonic Disruption: The collision of the Indian and Eurasian plates led to the rise of the Himalayas, drastically altering climate, rainfall, and wind patterns in Northeast India.
    • Habitat Loss: These shifts caused the region to cool and dry, rendering it unsuitable for tropical flora like Nothopegia.
    • Southward Migration: Over time, the plant spread to the Western Ghats, which offered a climatically stable refuge and allowed its survival.

    Significance of the Study:

    • Climate Lessons: The extinction and migration pattern of Nothopegia illustrates a deep-time example of species response to long-term climate change.
    • Scientific Value: Understanding ancient plant resilience aids in predicting survival pathways under current global warming scenarios.
    • Refuge Significance: The study highlights how climate refuges like the Western Ghats help preserve ancient lineages during major environmental changes.
    [UPSC 2025] Which of the following are the evidence of the phenomenon of continental drift?

    I. The belt of ancient rocks from the Brazil coast matches with those from Western Africa. II. The gold deposits of Ghana are derived from the Brazil plateau when the two continents lay side by side. III. The Gondwana system of sediments from India is known to have its counterparts in six different landmasses of the Southern Hemisphere.

    Select the correct answer using the code given below:

    Options: (a) I and III only (b) I and II only (c) I, II and III *(d) II and III only

     

  • Green Arabia Hypothesis in Human Evolution Research

    Why in the News?

    A recent study confirms that Arabia wasn’t always a desert wall but occasionally a green bridge between continents.

    About the Green Arabia Hypothesis:

    • Core Idea: It suggests that the Arabian Peninsula, now one of the driest places on Earth, experienced multiple humid phases over the past 8 million years, turning it into a green corridor for early migrations.
    • Challenge to Old Views: This theory challenges traditional models that excluded Arabia from early human dispersal routes in the ‘Out of Africa’ narrative.
    • Fossil Evidence: The discovery of fossils of crocodiles, hippos, and horses, dating up to 74,000 years ago, supports the claim that Arabia was once lush and habitable.

    Key Discoveries and Methods:

    • Archaeological Sites: Over 10,000 ancient lakebeds and sites over 500,000 years old were found, confirming Arabia’s role as a migration bridge between Africa and Eurasia.
    • Speleothem Analysis: 22 speleothem samples (mineral deposits formed within caves) from seven Saudi caves indicated humid phases between 7.44 million and 60,000 years ago.
    • Dating Techniques: Scientists used uranium-thorium dating to accurately time wet periods, revealing patterns linked to monsoon shifts and glacial cycles.
    • Environmental Impact: These wet intervals, though brief, supported vegetation, biodiversity, and water bodies, enabling human and animal settlements.

    Significance of the Study:

    • Biogeographic Role: Arabia is now viewed as a climate-sensitive migratory bridge, not a barrier, in human evolution and dispersal.
    • Climate Dependency: Human movement was influenced not just by geography, but by shifts in rainfall patterns and monsoonal activity.
    • Key Locations: Sites like Jubbah Oasis provided stone tools and lakebed evidence, validating early human habitation in the region.
    • Conclusion: Arabia’s periodic greening played a decisive role in early human migration, revising our understanding of ancient dispersal pathways out of Africa.
    [UPSC 2014] Which of the following phenomena might have influenced the evolution of organisms?

    1. Continental drift

    2. Glacial cycles Select the correct answer using the code given below.

    Options: (a) 1 only (b) 2 only (c) Both 1 and 2* (d) Neither 1 nor 2

     

  • India needs a sincere aircraft accident investigation

    Why in the News?

    The tragic aircraft accident in Ahmedabad on June 12, 2025, has once again thrown a spotlight on India’s deeply flawed aviation accident investigation system.

    Why is the AAIB’s independence in question despite being a statutory body?

    • Operational Control by MoCA: Although the AAIB is technically autonomous, it functions under the Ministry of Civil Aviation (MoCA), which also regulates airlines through the Directorate General of Civil Aviation (DGCA). Eg: In the Air India AI171 crash (2025), both the investigation and regulation were under MoCA’s control, raising concerns of bias and lack of transparency.
    • Leadership Appointments by the Same Authority: The MoCA appoints the heads of both the DGCA and the AAIB, undermining the bureau’s credibility as an independent investigative body. Eg: This centralized appointment structure is unlike the railway sector, where investigations are done by the Commissioner of Railway Safety, independent of the Railway Ministry.
    • Suppression of Uncomfortable Findings: Independent reviews and reports exposing deeper faults are often buried or ignored. Eg: The Air Marshal J.K. Seth Committee Report (1997) identified serious aviation safety issues, but it was never implemented because it told inconvenient truths.

    What systemic flaws affect India’s aviation safety framework?

    • Lack of Functional Independence in Investigations: The Aircraft Accident Investigation Bureau (AAIB) operates under the same ministry (MoCA) that regulates the aviation sector, compromising neutrality. Eg: After the Air India AI171 crash in June 2025, concerns were raised that the investigation might not be impartial due to overlapping roles of MoCA and AAIB.
    • Fragmented Oversight and Regulatory Capture: Aviation oversight in India suffers from poor coordination, limited resources, and influence by the very entities it is supposed to regulate. Eg: The J.K. Seth Committee Report (1997) pointed out such flaws, including regulatory capture, yet its recommendations remain largely unimplemented.
    • Reactive Rather Than Preventive Safety Culture: India’s aviation safety system often responds after accidents occur, rather than identifying and mitigating risks in advance.Eg: Multiple helicopter and flying school crashes in 2024–25 were not adequately investigated for systemic lapses, highlighting the absence of a proactive safety mechanism.

    How does MoCA’s control lead to conflict of interest in aviation oversight?

    • MoCA Controls Both Regulation and Investigation: MoCA oversees the Directorate General of Civil Aviation (DGCA) and also controls the Aircraft Accident Investigation Bureau (AAIB), creating an inherent conflict between promoting aviation and investigating its failures. Eg: In the Air India AI171 crash (2025), MoCA was in charge of both regulating the airline and investigating the crash, raising doubts about impartiality.
    • Lack of Independent Appointments: Senior officials in both DGCA and AAIB are appointed by MoCA, making it difficult for these bodies to act independently or challenge government or airline lapses. Eg: The J.K. Seth Committee (1997) warned about lack of independence due to MoCA’s direct control over top appointments, yet no structural change followed.
    • Investigative Findings May Be Influenced or Suppressed: When the regulator and investigator are under the same authority, reports may be watered down or delayed to avoid political or bureaucratic accountability. Eg: The Kozhikode crash (2020) report’s recommendations were not fully implemented, with experts citing MoCA’s influence in diluting critical findings.

    Why is pilot error often blamed in aviation accident reports?

    • Legally Convenient: Blaming the pilot simplifies legal liability and expedites insurance claims, avoiding lengthy investigations or broader accountability. Eg: In many crash reports, including Aurangabad crash (1993), pilot error was highlighted while structural or operational flaws were downplayed.
    • Shields Other Stakeholders: It protects airlines, maintenance agencies, air traffic control, and the regulator from scrutiny or punishment. Eg: In the Air India Express IX611 case (2018), suspected overloading was ignored while responsibility was pushed toward the flight crew.
    • Systemic Culture of Scapegoating: There’s a lack of a genuine no-blame culture in India’s aviation safety framework. Pilots, even posthumously, become convenient scapegoats. Eg: After the Kozhikode crash (2020), the pilot was quickly blamed, although systemic issues like runway design and poor weather protocols were also contributing factors.

    Way forward: 

    • Ensure Structural Independence of Investigative Bodies: Transfer the AAIB and DGCA out of the Ministry of Civil Aviation’s direct control and make them statutory authorities reporting to Parliament. This will eliminate conflict of interest and promote credible, impartial investigations.
    • Promote a No-Blame Safety Culture: Need to amend existing rules to prevent automatic criminal liability for pilots unless gross negligence is proven (e.g., Rule 19(3) of Aircraft Rules, 1937).

    Mains PYQ:

    [UPSC 2018] Describe various measures taken in India for Disaster Risk Reduction (DRR) before and after signing ‘Sendai Framework for DRR (2015-2030)’. How is this framework different from ‘Hyogo Framework for Action, 2005?

    Linkage: The article explicitly frames an aircraft accident as a “wake-up call” and argues that India needs a system that “prevents failures, and not just manages the damage.” It states, “We cannot keep firefighting. We need a system that prevents failures”. This directly relates to the concept of Disaster Risk Reduction (DRR), which emphasises proactive measures and preparedness over reactive response.

  • Shipki La Mountain Pass opened for Tourists

    Why in the News?

    For the first time since India’s independence, the Shipki La pass in Himachal Pradesh has been opened to domestic tourists, marking a historic shift in India’s border tourism strategy.

    About Shipki La Pass:

    • It is a high-altitude mountain pass at 3,930 meters in the Kinnaur district of Himachal Pradesh, on the India–Tibet (China) border.
    • It is one of only 3 official border trading points between India and Tibet, along with Nathu La (Sikkim) and Lipulekh (Uttarakhand).
    • The Sutlej River (called Langqen Zangbo in Tibet) enters India near Shipki La, adding geographical importance to the area.
    • The pass lies along National Highway 5 (NH5) and is considered one of the highest motorable roads in India.
    • Historically, it served as a major trade route, enabling exchange of salt, wool, spices, yak tails, and tea between India and Tibet.
    • Trade was stopped in 1962 after the India-China war, resumed in 1992, but was halted again during COVID-19.
    • On June 9, 2025, Himachal Pradesh opened the pass to Indian tourists for the first time since Independence.
    • The initiative is part of a “Border Tourism” strategy, which includes the launch of the Sarhad Van Udyan (Border Forest Park).
    • It is also being considered as an alternate route for the Kailash Mansarovar Yatra.

    Other Important Himalayan Passes:

    • Ladakh and Jammu & Kashmir:
      • Khardung La (5,359 m) – Among the highest motorable passes; connects Leh with Nubra Valley.
      • Zoji La – Links Srinagar with Leh; vital for year-round Ladakh access.
      • Chang La, Baralacha La, Umling La (5,798 m) – Crucial for Leh connectivity and defense.
      • Rezang La – Famous for the 1962 India-China war battle.
      • Karakoram Pass, Aghil Pass, Demchok Pass – Strategic India-China border passes.
    • Himachal Pradesh:
      • Rohtang Pass – Connects Kullu with Lahaul-Spiti; key for tourism and logistics.
      • Parang La – Links Spiti Valley and Parvati Valley; used by trekkers and herders.
      • Shipki La – Now open to tourists; historical Indo-Tibetan trade route.
    • Uttarakhand:
      • Lipulekh Pass (5,632 m) – Used for Kailash Mansarovar Yatra.
      • Mana Pass – One of the highest vehicle-accessible passes; connects to Tibet.
      • Niti Pass, Milam Pass, Kuthi Pass – Historical trade and pilgrimage routes.
    • Sikkim:
      • Nathu La – Major border trade route; part of the ancient Silk Route.
      • Jelep La – Historical route linking Sikkim with Lhasa via Chumbi Valley.
    • Arunachal Pradesh:
      • Se La, Bum La – Connect to Tawang and Bhutan border.
      • Pangsau Pass, Diphu Pass – Connect Arunachal with Myanmar; important for WWII history and connectivity.
    [UPSC 2007] Which one of the following Himalayan passes was reopened around in the middle of the year 2006 to facilitate trade between India and China?

    Options: (a) Chang La (b) Jara La (c) Nathu La (d) Shipki La

     

  • Massive eruption of Italy’s Mount Etna

    Why in the News?

    Mount Etna, Europe’s largest active volcano, has erupted sending ash, smoke, and rock fragments several kilometres into the sky.

    Why do Volcanoes Erupt?

    • Magma Formation: Deep within Earth, high temperature and pressure melt rocks into magma.
    • Gas Expansion: Magma contains gases like water vapor, CO₂, and SO₂. As magma rises, the pressure drops, allowing these gases to form bubbles, increasing internal pressure.
    • Crustal Weaknesses: At tectonic boundaries or mantle plumes, cracks and faults in Earth’s crust provide pathways for magma to escape.
    • Eruption Mechanism:
      • As pressure builds, magma is pushed upwards.
      • If blocked, the gas expansion can explode through the crust, ejecting lava, ash, and gases.
    • Signals: If magma flow is suddenly stopped by solid rock, it may create low-frequency seismic waves (pre-eruption tremors).

    Next Census to conclude by March 2027

    About Mount Etna:

    • Location: Situated on the east coast of Sicily, Italy, near the city of Catania.
    • Type: Mount Etna is a stratovolcano (also called a composite volcano), which is formed from layers of hardened lava, volcanic ash, and rocks.
    • Height: It stands at approximately 3,300 meters, making it the tallest volcano in Europe south of the Alps.
    • Recognition: Declared a UNESCO World Heritage Site in 2013, with documented volcanic activity for at least 2,700 years.
    • Eruption Record: Etna is almost constantly active. Notable eruptions have occurred in 1400 B.C., 1669, 2001, 2018, 2021, 2024, and 2025.
    • Volcanic Activity Style: Known for Strombolian and effusive eruptions, with occasional Plinian eruptions (rare and more explosive).

    Reasons Behind the June 2025 Eruption:

    • Nature of Eruption: The eruption is classified as either Strombolian or possibly Plinian, depending on interpretation:
      • Strombolian Eruption: Characterized by moderate explosive bursts, caused by gas bubbles in magma suddenly bursting at the surface.
      • Plinian Eruption: Some volcanologists suggest this classification due to the large ash column that may have reached the stratosphere.
    • Eruption Trigger: The eruption likely began due to pressure buildup from gas within the magma chamber, leading to collapse of the southeast crater and lava flows.
    [UPSC 2024] Consider the following:

    1. Pyroclastic debris

    2. Ash and dust

    3. Nitrogen compounds

    4. Sulphur compounds

    How many of the above are products of volcanic eruptions?

    Options: (a) Only one (b) Only two (c) Only three (d) Only four*