Why in the News?

The extreme conditions in eastern Spain which saw Valencia get a year’s worth of rain in just 8 hours can be blamed on an event locally known as Depresion Aislada en Niveles Altos (DANA).

What is DANA?

• Depresion Aislada en Niveles Altos (DANA), is commonly referred to as the “cold drop” in English.
• It is a meteorological phenomenon in the western Mediterranean region that brings intense rainfall and flooding.
• The term “DANA” was coined by Spanish meteorologists to specifically describe this weather phenomenon.

Features and Location:

• DANA occurs when cold air from the Polar Regions separates from the polar jet stream and descends over the warmer Mediterranean Sea.
• The contrast between cold air aloft and warm, moist air near the surface causes atmospheric instability, leading to the rapid formation of cumulonimbus clouds and intense thunderstorms.
• It primarily affects Spain and Portugal but can also impact Italy, France, and other areas around the Mediterranean Sea.
• This occurs in autumn and spring, as temperature variations are more pronounced during these seasons.

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Why in the News?

West Bengal and Odisha experienced heavy rainfall as Tropical Cyclone Dana is anticipated to make landfall later tonight.

What is the “Landfall” of a Cyclone?

• Landfall occurs when a tropical cyclone moves from the sea onto the land.
• As per the IMD, a cyclone makes landfall when the centre of the storm, or its eye, crosses the coast.
• Landfall should not be confused with a “direct hit”, where the eyewall (area of high winds) hits land but the eye of the cyclone remains offshore.
• According to the National Oceanic and Atmospheric Administration (NOAA), a cyclone’s strongest winds may still impact land even if the centre of the storm does not reach the coast.

How long does a Cyclone Landfall last?

• The duration of landfall typically lasts a few hours, depending on the wind speed and size of the storm.
• For cyclone Dana, the landfall process is expected to last five to six hours with wind speeds around 125 km/h, impacting a wide region.
• Cyclones usually weaken after landfall as they lose their moisture supply and experience increased surface friction.
• While landfall is often the most destructive phase of a cyclone, it also signals the beginning of the cyclone’s dissipation.

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Why in the News?

A yacht sank off the coast of Sicily, Italy after being hit by a Waterspout.

What are Waterspouts?

• A waterspout is a rotating column of air and mist over a water body.
• It is a weaker relative of tornadoes and typically lasts for about five minutes, although it can occasionally last up to 10 minutes.
• Size and Strength:
  • Average diameter: Around 165 feet.
  • Wind speeds: Can reach up to 100 km/hr.
• Waterspouts are more common in tropical waters but can form anywhere with high humidity and relatively warm water temperatures compared to the overlying air.

Types of Waterspouts:

• Tornadic Waterspouts

1. 1. • These are actual tornadoes that either form over water or move from land to water.

• They are associated with severe thunderstorms and can be accompanied by high winds, large hail, and dangerous lightning.

• Fair-Weather Waterspouts:

1. • These are more common and form only over water during fair weather.
   • They are generally smaller and less dangerous than tornadic waterspouts.

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Why in the News?

After making landfall in the Philippines, Typhoon Gaemi is heading towards Taiwan.

What is a Typhoon?

• A typhoon is a mature tropical cyclone that forms in the Northwest Pacific Ocean, primarily between 100°E and 180°E.
• It is characterised by strong winds, and heavy rain, and can cause significant damage due to high wind speeds, storm surges, and flooding.

Factors causing its formation:

• It needs sustained ocean temperatures of 26.5°C or higher.
• High moisture content in the mid-troposphere.
• Presence of the Coriolis force to initiate rotation.
• Minimal vertical wind shear to allow for storm growth.
• Atmospheric instability to promote rising motion and thunderstorm activity.
• An initial low-pressure area or tropical wave to trigger development.
  • Formation Regions: Northwest Pacific Ocean in areas east of the Philippines, southeast of Japan, and near Taiwan; South China Sea and in Western North Pacific near the Mariana Islands and Guam.

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Why in the News?

• The origin of life on Earth remains one of the world’s most enduring mysteries.
  • Numerous competing theories exist, but none have conclusive proof.
  • A significant concept in understanding the origin of life is the Last Universal Common Ancestor (LUCA).

What is the Last Universal Common Ancestor (LUCA)?

• Researchers believe that all life forms— the Bacteria, the Archaea, and the Eukarya —originated from a single cell known as the last universal common ancestor (LUCA).
• It is suggested to have been a “cellular organism that had a lipid bilayer and used DNA, RNA, and protein“.
• There is a lack of clarity about direct fossil evidence of LUCA.
• However, the shared features of modern genomes provide significant insights into this ancient ancestor.

Recent Research Findings on LUCA’s Age and Genome

• Researchers at the University of Bristol and Exeter estimate that LUCA originated around 4.2 billion years ago, nearly 1 billion years earlier than previously thought. 
  • They obtained evidence from the 3.3 km deep Candelabra’ hydrothermal vent on the Mid-Atlantic Ridge.
• LUCA had a small genome of about 2.5 million bases encoding 2,600 proteins, sufficient for survival in a unique niche.
• Its metabolites may have created a secondary ecosystem for other microbes.
• The presence of immunity genes in LUCA suggests it had to defend against viruses.

Evidence Verification using Miller-Urey Experiment

• In 1952, Stanley Miller and Harold Urey conducted an experiment at the University of Chicago, simulating lightning strikes on a mixture of methane, ammonia, and water, which resulted in the formation of amino acids.
• This demonstrated that complex organic compounds could arise from inorganic compounds under the right conditions.

Which is older: LUCA or fossils?

• LUCA’s estimated origin at 4.2 billion years predates the earliest fossil records by almost 1 billion years.
• Fossil records from the Pilbara Craton in Australia suggest life emerged around 3.4 billion years ago, but the study pushes this date back.

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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.

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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.

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.

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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.

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.

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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.

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.’

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Why in the news?

A rare celestial event unfolded as four solar flares called as Sympathetic Solar Flares simultaneously, signaling the onset of the Sun’s dynamic 11-year solar cycle.

What are Sympathetic Solar Flares?

• Sympathetic solar flares are solar eruptions that occur in close temporal and spatial proximity to another solar flare or eruption.
• These events are believed to be interconnected through magnetic fields or other physical processes occurring on the Sun.
• When a solar flare or eruption happens on the Sun, it releases a burst of electromagnetic radiation and charged particles into space.
• In some cases, the energy released during these events can cause disturbances in the Sun’s magnetic field.
• These disturbances can trigger the occurrence of additional flares loop or eruptions in nearby regions of the Sun’s surface.
• This event follows coronal mass ejections (CMEs) and intense plasma bursts.

Implications for Earth

• Potential impacts include disruptions to power grids, interference with communication networks, and increased radiation exposure for astronauts and aircraft passengers.
• Solar storms can lead to spectacular natural light shows known as auroras, which are typically visible near the Earth’s magnetic poles.

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Why in the news?

• An earthquake of magnitude 4.8 hit the New York City in a rare event.
• The Ramapo Fault in Appalachian Mountains near New Jersey is a being considered as a reason behind this earthquake.

About Ramapo Fault

• Fault lines are fractures in the Earth’s crust that facilitate movement of tectonic plates, triggering earthquakes.
• The Ramapo Fault is resulted from tectonic activity associated with the breakup of the supercontinent Pangaea during the Mesozoic Era.
• It is primarily a right-lateral strike-slip fault, formed by horizontal movement along the fault line due to the ongoing motion between the North American and Eurasian plates.
• While the Ramapo Fault is not as seismically active as faults in other regions, it has experienced earthquakes in the past and remains a potential source of seismic hazards.

Geographical Distribution:

• The fault extends across three states in the northeastern United States: Pennsylvania, New Jersey, and New York.
• The fault crosses various topographic features, including rift valleys, hills, and ridges, reflecting the diverse geological history of the region.
• It intersects with the Appalachian Mountains, influencing the overall topography of the surrounding areas.

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Why in the News?

• Some recent study about the Singhbhum Craton in India, reveals that explosive volcanic eruptions were frequent around 3.5 billion years ago in regions that are also present in South Africa, and Australia.

What are Cratons?

• Cratons are stable, ancient portions of the continental lithosphere, consisting of Earth’s two topmost layers—the crust and the uppermost mantle.
• Cratons are typically found in the interiors of tectonic plates and are characterized by their ancient crystalline basement rock, often dating back to the Archean Eon.
• Mantle plume events have played a significant role in the evolution of cratons.

About Singhbhum Craton:

• The Singhbhum Craton is a geological region in India.
• Location: It is located in eastern India, covering parts of the states of Jharkhand, Odisha, and West Bengal. The craton is separated from the Bastar Craton by the Mahanadi Graben and is in the vicinity of two Proterozoic mobile belts: the Satpura Mobile Belt and the Eastern Ghat Mobile Belt.
• Geological features:
  • The rocks in the Singhbhum Craton are predominantly of Archean age, ranging from Paleoarchean to Paleoproterozoic.
  • It is a part of the larger Indian Shield, which is a stable continental crust that formed during the Archean Eon.
  • The Singhbhum Craton is known for its abundant occurrences of Banded Iron Formations (BIFs), which are closely associated with basic volcanic and ultrabasic intrusive. The craton is also known for its iron ore deposits, which are found in the Iron Ore Group (IOG) and are closely associated with lavas and tuffs.
  • The Singhbhum Craton has undergone regional metamorphism of the amphibolite facies and is believed to have evolved as a consequence of multiple phases of compressive deformation.
  • The craton is made up of multiple pulses of discrete mantle plume events, resulting in a complex geological history.

What are the recent key findings?

• Submarine Mafic Volcanism: The prevalence of submarine mafic volcanic eruptions between 3.5 and 3.3 billion years ago is documented, enriching our understanding of ancient volcanic and sedimentary processes.
• Geodynamic Insights: Comparative analysis enhances our comprehension of early Earth tectonic activities and surface/atmospheric processes during the Archaean.

Research Methodology Used:

• Field Studies and Radiometric Dating: Detailed field-based studies coupled with uranium-lead radiometric-age dating were employed to establish geological timelines and understand magma crystallization.
• Comparative Analysis: The geological similarities between the Singhbhum Craton and counterparts in South Africa and Australia were studied, focusing on volcanic eruption patterns.

Implications and Significance of the study:

• Earth’s Formative Years: Insights into Earth’s early tectonic activities contribute significantly to understanding the planet’s formative years.
• Habitable Conditions: Unique geological features, such as greenstone belts, provide invaluable information about early habitable conditions and the emergence of life.
• Global Geodynamic Processes: Comparative studies across cratons worldwide facilitate the construction of comprehensive models elucidating ancient geodynamic processes prevalent during the Archaean.

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Central Idea

• Residents in the Arctic have witnessed an extraordinary atmospheric display of Polar Stratospheric Clouds (PSCs).

Polar Stratospheric Clouds (PSCs)

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Central Idea

• A volcanic eruption occurred near Iceland’s capital between Sýlingarfell and Hagafell, near the town of Grindavik on the Reykjanes Peninsula.

Iceland: ‘Land of Fire and Ice’

• Geographical Location: Iceland is situated just south of the Arctic Circle in the North Atlantic Ocean.
• Tectonic Setting: The country lies on the Mid-Atlantic Ridge, marking the boundary between the North American and Eurasian tectonic plates.
• Unique Landscape: Iceland’s landscape features geysers, glaciers, mountains, volcanoes, and lava fields, housing 33 active volcanoes – the highest number in Europe.
• Historical Settlement: The first human settlement in Iceland dates back to 874 by Norsemen from Scandinavia, leading to the founding of Reykjavik.

Recent Volcanic Activity on the Reykjanes Peninsula

• Historical Dormancy: The Reykjanes Peninsula had not experienced volcanic eruptions for 800 years until recently.
• Recent Eruptions: The current eruption is the fourth in less than three years on the peninsula, indicating a potential new era of volcanic activity.
• Eyjafjallajokull Eruption: The last major volcanic event in Iceland that gained global attention was the 2010 eruption of Eyjafjallajokull.
• Eruption Timeline and Impact: The volcano erupted twice in March and April 2010, spreading an ash cloud across continents and disrupting air traffic on the North Atlantic route for six days – the longest disruption since World War II.

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Central Idea

• Cyclone Michaung (name suggested by Myanmar) makes landfall in Tamil Nadu and Andhra Pradesh.
• Michaung is the fourth tropical cyclone over the Bay of Bengal this year.

About Cyclone Michaung

• Uncommon Intensity: December cyclones in the North Indian Ocean typically do not reach high intensities. Michaung, with its severe storm classification, is an exception.
• Upgraded Intensity: Initially predicted as a tropical cyclone, IMD upgraded Michaung to a ‘severe’ storm due to its unexpected intensification.
• Heat Index Contribution: The intensification is attributed to the above-normal heat index values off the southern Andhra Pradesh coast.

Indian Tropical Storms: An Overview

• Annual Cyclones: The North Indian Ocean basin averages about five cyclones per year, predominantly in the Bay of Bengal.
• Arabian Sea Cyclones: Though less frequent, Arabian Sea cyclones often reach higher intensities and can cause extensive damage.
• Peak Cyclone Seasons: Cyclones are most common during pre-monsoon (April-June) and post-monsoon (October-December) months, with May and November seeing more intense storms.

Factors Influencing Storm Intensification

• Ocean Heat: Cyclones draw energy from warm ocean temperatures, typically around 26 degrees Celsius or higher.
• Tropical Cyclone Heat Potential (TCHP): This oceanographic parameter is crucial in cyclone genesis and intensification.
• Complex Atmospheric Conditions: Various atmospheric factors like wind shear, convection, and air-sea interactions also play a role in cyclone development.
• Coriolis Effect: This effect influences cyclone formation in the northern hemisphere, causing air to move anticlockwise in low-pressure areas.

Back2Basics: Extratropical and Tropical Cyclones

• General Definition: Cyclones are large-scale air systems rotating around a low-pressure center, often accompanied by violent storms.
• Extratropical Cyclones: Found outside the tropics, these cyclones have a cold core and gain energy from interactions between cold and warm air masses. They can form over both land and sea.
• Tropical Cyclones: These form in tropical regions and are powered by the condensation of water vapor. They lack associated warm or cold fronts and are known as hurricanes or typhoons in different regions.

Cyclone Naming Process

• Rotational Basis for Naming: The naming of cyclones is done by countries on a rotational basis, following certain existing guidelines.
• Responsibilities of RSMCs and TCWCs: Worldwide, there are six regional specialized meteorological centers (RSMCs) and five regional Tropical Cyclone Warning Centers (TCWCs) mandated for issuing advisories and naming of tropical cyclones.
• IMD’s Role: IMD is one of the six RSMCs providing tropical cyclone and storm surge advisories to 13 member countries under the WMO/Economic and Social Commission for Asia-Pacific (ESCAP) Panel.
• Naming Authority of IMD: RSMC, New Delhi, is also mandated to name the tropical cyclones developing over the north Indian Ocean, including the Bay of Bengal and the Arabian Sea.
• Guidelines for Naming: Some rules are to be followed while naming cyclones, such as being neutral to politics, religious beliefs, cultures, and gender, avoiding offensive or cruel names, and keeping the name short and easy to pronounce.
• Future Naming: After ‘Michaung’, the next cyclone as per India’s suggestion will be named ‘Tej’.

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Central Idea

• The Indian National Centre for Ocean Information Services (INCOIS), a division under the Ministry of Earth Sciences (MoES), has made a significant discovery regarding the Southern Annular Mode (SAM), a crucial climate pattern.
• Their research has revealed that SAM plays a pivotal role in influencing sea conditions across the Indian Ocean.

What is Southern Annular Mode (SAM)?

Role of Ocean Surface Waves

• Coastal Processes: Ocean surface waves are key players in shaping coastal processes, impacting shoreline erosion, sediment transport, coastal engineering, and recreational activities.
• Scientific Approach: The scientific team leveraged 40 years of data (1979 to 2018) from the European Centre for Medium-Range Weather Forecast.

Positive and Negative SAM Phases

• Positive SAM Phase: During a positive SAM phase, a cyclic pattern of warm sea surface temperature anomalies emerges, accompanied by strong winds that increase wave activity in the Indian Ocean. A new swell generation region along the east African coast contributes to heightened wave heights in the Arabian Sea.
• Negative SAM Phase: Conversely, during a negative SAM phase, the eastern tropical southern Indian Ocean becomes the primary region for generating swells, resulting in reduced wave heights in the Arabian Sea.

Significance of SAM

• Coastal Planning: Understanding SAM allows for better coastal planning, helping coastal communities prepare for the impact of changing sea conditions.
• Resource Management: SAM insights can aid in more efficient resource management, optimizing the utilization of marine resources.
• Disaster Preparedness: Knowledge of SAM patterns can enhance disaster preparedness efforts, enabling timely response to potential ocean-related disasters.
• Wave Predictions: The research contributes to improving wave predictions, offering advanced forecasting capabilities.
• Benefiting Stakeholders: Stakeholders in the blue economy, including shipping, maritime boards, and the oil industry, can optimize their multi-million-dollar operations at sea based on SAM insights.

Implications for Various Sectors

• Monsoon Season Impact: Typically, inland vessel operations and oil exploration activities face restrictions during the monsoon season.
• Fair Sea State Windows: Predicting SAM phases through the Ocean Forecasting System can identify “Fair Sea state windows” during monsoons.
• Impact on Blue Economy: These fair windows can be leveraged by oil and shipping industries, making a significant contribution to blue economy activities along the Indian coast

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Central Idea

• Ball lightning, an intriguing natural phenomenon characterized by luminous spherical objects appearing during thunderstorms, has intrigued observers for generations.
• They are sometimes accompanied by hissing sounds and unusual odors, adding to the mystery surrounding their origin and behavior.

Understanding Lightning and Ball Lightning

• Normal lightning: Lightning is a natural electrical discharge that occurs due to differences in electrical charges within clouds or between clouds and the Earth’s surface during storms.
• Ball Lightning: Ball lightning has been documented in historical records, with instances dating back to 1638 when a “great ball of fire” entered an English church through a window, hinting at its potential danger.
• Scientific Recognition: While debates persist, most scientists acknowledge the existence of ball lightning, even though its underlying mechanisms are not fully understood.
• Chinese Research: A study conducted by researchers from Lanzhou’s Northwest Normal University in 2012 inadvertently captured a ball lightning event during a thunderstorm. Their findings confirmed the presence of elements such as silicon, iron, and calcium in the luminous sphere, matching the composition of local soil.

Possible Causes of Ball Lightning

• Ground Strike Theory: Some scientists propose that ball lightning may result from ground strikes, initiating chemical reactions between oxygen and vaporized soil elements. This process creates ionized air or plasma, resembling phenomena like St. Elmo’s Fire.
• Glass-Related Hypothesis: Another theory suggests that ball lightning might form due to the buildup of atmospheric ions on glass surfaces, creating an electrical field capable of generating discharges.
• Microwave Radiation: An alternative theory posits that ball lightning could be linked to microwave radiation produced when lightning strikes the Earth’s surface, potentially encapsulating it in a plasma bubble.

Association with Earthquakes

• In rare instances, ball lightning has been observed in connection with earthquakes, displaying as bluish flames, sudden bright flashes from the ground, or floating orbs.
• A 2014 study exploring earthquake lights proposed that specific rock types release electrical charges during seismic waves, leading to luminous displays.

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Central Idea

• On October 15, Afghanistan was struck by a formidable earthquake with a magnitude of 6.3, adding to the woes of a nation still reeling from a series of devastating quakes just days earlier.
• This recent seismic activity reflects Afghanistan’s turbulent history of earthquakes, often with catastrophic consequences.

Understanding Earthquakes

• Tectonic Plate Movement: The Earth’s lithosphere consists of tectonic plates that move due to internal heat energy. Fault lines are formed along the discontinuities where these plates interact.
• Earthquake Mechanism: Earthquakes occur when these lithospheric plates suddenly slip past one another, releasing energy that propagates as seismic waves. The point where the slip starts is known as the focus or hypocenter, with the epicenter being its surface projection.

What exactly causes Earthquakes?

• As we know, the earth’s outermost surface, crust, is fragmented into tectonic plates.
• The edges of the plates are called plate boundaries, which are made up of faults.
• The tectonic plates constantly move at a slow pace, sliding past one another and bumping into each other.
• As the edges of the plates are quite rough, they get stuck with one another while the rest of the plate keeps moving.
• Earthquake occurs when the plate has moved far enough and the edges unstick on one of the faults.
• The location below the earth’s surface where the earthquake starts are called the hypocenter, and the location directly above it on the surface of the earth is called the epicentre.

Afghanistan’s Seismic Vulnerability

• Tectonic Plate Intersection: Afghanistan’s location atop the convergence of the Indian and Eurasian tectonic plates results in frequent seismic activity.
• Eurasian Plate: Afghanistan sits on the Eurasian Plate, with the Arabian Plate subducting northward in the west and the Indian Plate doing the same in the east.
• Complex Geology: The Hindu Kush mountain range and the Pamir Knot add complexity to this geological region, leading to folding, faulting, and earthquakes.
• Continual Compression: The northward movement of the Indian Plate toward Eurasia causes compression, uplifting the Himalayas, and transmitting tectonic stress. This leads to crustal deformation, faulting, and seismic activity.
• Active Fault Systems: Afghanistan is intersected by active fault systems like the Chaman Fault and the Main Pamir Thrust, which are prolific sources of earthquakes.

History of Earthquake Afghanistan

• October 11 Quakes: In October 2023, a series of powerful earthquakes, including a magnitude 6.3 tremor, wreaked havoc in Herat province, claiming the lives of at least a thousand people.
• June 2022 Tragedy: A magnitude 6.1 earthquake in Khost and Paktika provinces in June 2022 left over 1,000 casualties.
• 2015 Catastrophe: A major earthquake in northeastern Afghanistan in 2015 claimed over 200 lives in Afghanistan and northern Pakistan.
• 2002 Devastation: A 6.1-magnitude earthquake in 2002 resulted in approximately 1,000 casualties in northern Afghanistan.
• 1998 Disaster: In 1998, northeast Afghanistan experienced a catastrophic earthquake and subsequent tremors, causing the loss of at least 4,500 lives.

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Central Idea

• A devastating earthquake struck Morocco, resulting in significant casualties and damage.

Details of the Moroccan Earthquake

• Shallow Epicenter: The quake’s epicentre was near the town of Ighil, approximately 70 km southwest of Marrakech. It was considered fairly shallow, with varying depth estimates.
• Higher Energy: Shallow earthquakes are typically more dangerous as they carry more energy, making them more destructive compared to deeper quakes.

Major Causes

• Tectonic Convergence: The earthquake resulted from the northward convergence of the African plate with the Eurasian plate along a complex plate boundary.
• Faulting: The USGS attributed the quake to oblique-reverse faulting at a shallow depth within the Moroccan High Atlas Mountain range.
• Fault Classification: Oblique-slip faults exhibit characteristics of both dip-slip and strike-slip faults, occurring in areas of compression where tectonic plates converge.

Why discuss this?

• Low Seismicity: Earthquakes are uncommon in North Africa, with low seismicity rates along the northern margin of the continent.
• Historic Strength: This earthquake was the strongest ever recorded in the mountainous region, catching Morocco unprepared for such an event.
• Construction Vulnerabilities: Many Moroccan buildings, especially in rural areas and older cities, are not constructed to withstand strong tremors.

What is an Earthquake?

• An earthquake is an intense shaking of the ground caused by movement under the earth’s surface.
• It happens when two blocks of the earth suddenly slip past one another.
• This releases stored-up ‘elastic strain’ energy in the form of seismic waves, which spreads through the earth and cause the shaking of the ground.

What exactly causes Earthquakes?

• As we know, the earth’s outermost surface, crust, is fragmented into tectonic plates.
• The edges of the plates are called plate boundaries, which are made up of faults.
• The tectonic plates constantly move at a slow pace, sliding past one another and bumping into each other.
• As the edges of the plates are quite rough, they get stuck with one another while the rest of the plate keeps moving.
• Earthquake occurs when the plate has moved far enough and the edges unstick on one of the faults.
• The location below the earth’s surface where the earthquake starts are called the hypocenter, and the location directly above it on the surface of the earth is called the epicentre.

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Central Idea

• In the ever-changing tapestry of Earth’s climate, the Fujiwhara effect has emerged as a captivating and consequential phenomenon.
• With cyclones intensifying due to global warming, this intricate ‘dance’ between cyclones is garnering attention.

Why in news?

• Surprising Weather: Recently, a storm named Hurricane Hilary brought a tropical twist to the US west coast. It’s part of a series of odd weather happenings there.
• Wet Weather: Earlier this year, California had an unexpected rainy season with lots of wet storms, called ‘atmospheric rivers.’
• Fujiwhara Show: During one of these storms, something special occurred—an effect named after a scientist. Let’s dive into the details.

Decoding the Fujiwhara Effect

• Cyclone Waltz: Imagine two cyclones (or big storms) spinning in the same direction. When they get close, they begin a kind of dance around a common center.
• Outcome of the Dance: Depending on the strength of the cyclones, they might merge, spin together, or one might absorb the other.
• Super Cyclone: Rarely, if both cyclones are super strong, they can become one mega cyclone that causes big trouble.

Historical Context and Impact

• Origins and Discovery: The Fujiwhara effect got its name from a Japanese scientist who first talked about it in 1921. It was seen happening for real in 1964.
• Effects Unleashed: This unusual dance can be fierce. It has caused strong winds, broken windows, and power problems in some areas.
• Guessing Game: The Fujiwhara effect is tricky for weather experts. It’s hard to predict what will happen when two cyclones dance together.

Climate Change Connection

• More Frequent Moves: The Fujiwhara effect is showing up more often now. Experts believe it’s because our world is getting hotter and ocean waters are warming up.
• Hotter Waters: Because of global warming, storms are getting stronger. For instance, in Taiwan, typhoons have become 35% stronger since 1977 due to warmer oceans.

Implications

• Nature’s Symphony: The Fujiwhara effect is like a nature’s concert, showing us how everything is connected in our climate.
• Future Twist: As storms get more powerful, the Fujiwhara effect could become even more important and harder to understand.
• Planet’s Dance: The Fujiwhara effect teaches us about our planet’s rhythm and how important it is to take care of our home.

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Central Idea

• AWG’s Proposal: The Anthropocene Working Group (AWG) proposes a new geological epoch called the Anthropocene.
• Reference Point: The unique reference point for the Anthropocene is Crawford Lake near Toronto in Canada’s Ontario Province.

Understanding the Anthropocene Epoch

• Coined Term: The Anthropocene epoch was first coined by Nobel Prize-winning chemist Paul Crutzen and biology professor Eugene Stoermer in 2000.
• Human Impact: The Anthropocene represents the geological time interval characterized by radical changes in the Earth’s ecosystem due to human impact, particularly since the onset of the Industrial Revolution.
• Environmental Changes: Numerous phenomena associated with the Anthropocene include global warming, sea-level rise, ocean acidification, mass-scale soil erosion, deadly heat waves, and environmental deterioration.
• Geological Strata: The AWG’s website states that these changes are reflected in a distinctive body of geological strata, with the potential to be preserved into the far future.

Evidence from Crawford Lake

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• Selected Site: Crawford Lake in Canada’s Ontario Province was chosen by geologists for examination over 11 other potential sites.
• Preserved Sediments: The lake’s layers of sediment have preserved the annual impact of human activities on the Earth’s soil, atmosphere, and biology.
• Shift in Mid-20th Century: The analysis of Crawford Lake’s bottom sediments reveals a clear shift from the mid-20th century, surpassing the bounds of the previous Holocene epoch.
• Captured Fallout: Over the years, the lake’s sediments have captured the fallouts of large-scale burning of fossil fuels, explosion of nuclear weapons, and dumping of plastic and fertilizers on land and in water bodies.

Debate and Disagreements

• Scientific Community Disagreements: Not all geologists agree on the reality of the Anthropocene epoch.
• Debate Points: Disagreements revolve around the precise start of the epoch, whether it has already begun, and the sufficiency of evidence to prove its advent.

The Geological Time Scale

• Divisions and Categories: The Earth’s geological time scale is divided into five broad categories: eons, eras, periods, epochs, and ages.
• Fossil-Based Boundaries: Boundaries on the geological time scale correspond to the origination or extinction of specific types of fossils.
• Current Classification: Currently, we are in the Phanerozoic eon, Cenozoic era, Quaternary period, Holocene epoch, and Meghalayan age.

AWG’s Findings and Next Steps

• Selection of Crawford Lake: Crawford Lake was chosen due to its preserved sediment layers that provide an annual record of human impact.
• Overwhelming Effects: Distinct and multiple signals in the lake’s sediments starting around 1950 demonstrate that the effects of human activity overwhelm the Earth system.
• Unique Global ‘Fingerprint’: The presence of plutonium resulting from nuclear weapon detonations serves as a stark indicator of humanity’s dominant influence on the planet.
• Approval Process: The AWG plans to present a proposal to the Subcommission on Quaternary Stratigraphy (SQS) and the International Commission on Stratigraphy (ICS) for approval.
• Final Approval: The final approval is expected to be granted at the 37th International Geological Congress in Busan, South Korea, next year.

Conclusion

• Compelling Evidence: Geologists’ examination of Crawford Lake provides compelling evidence for the existence of the Anthropocene epoch.
• Challenging Conventional Timeline: The proposal for the Anthropocene epoch challenges the conventional understanding of the Earth’s official geological timeline.
• Future Determination: Further discussions and approvals by international geological bodies will determine the recognition and acceptance of the Anthropocene epoch.

Back2Basics: Geological Time Scale

• The Geological Time Scale is a system used by geologists and palaeontologists to divide Earth’s history into distinct time intervals based on significant geological and biological events.
• It provides a framework for organizing and understanding the vast expanse of time since the formation of the Earth, approximately 4.6 billion years ago, up to the present day.
• The Scale is divided into several hierarchical units, including eons, eras, periods, epochs, and ages.

Here is a simplified overview of the major divisions:

(1) Eon: The largest division of time on the Geological Time Scale. The history of Earth is typically divided into four eons:

• Hadean Eon: Represents the earliest stage of Earth’s history, from its formation to around 4 billion years ago.
• Archean Eon: Covers the period from around 4 billion to 2.5 billion years ago. It includes the formation of the Earth’s crust, the emergence of life, and the development of the first continents.
• Proterozoic Eon: Encompasses the time between 2.5 billion and 541 million years ago. It includes significant evolutionary developments, such as the emergence of complex multicellular life.
• Phanerozoic Eon: The current eon, spanning from 541 million years ago to the present. It is further divided into eras.

(2) Era: The second-largest division of time, encompassing longer periods of geological history within an eon. The Phanerozoic Eon is divided into three eras:

• Paleozoic Era: Covers the time from 541 million to 252 million years ago. It is known for the diversification of life, including the appearance of complex marine organisms, fish, insects, and the first terrestrial plants.
• Mesozoic Era: Spans from 252 million to 66 million years ago. It is often referred to as the “Age of Reptiles” and includes the dominance of dinosaurs, as well as the rise of mammals and birds.
• Cenozoic Era: Extends from 66 million years ago to the present. It is sometimes called the “Age of Mammals” and includes the diversification and proliferation of mammals, the appearance of humans, and the development of modern ecosystems.

(3) Period: A subdivision of an era, representing a distinct interval of time characterized by specific geological and biological events. For example:

• The Paleozoic Era is divided into periods such as the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian.
• The Mesozoic Era is divided into periods including the Triassic, Jurassic, and Cretaceous.
• The Cenozoic Era is divided into periods such as the Paleogene, Neogene, and Quaternary.

(4) Epoch: A smaller subdivision of a period, representing a shorter interval of time. Epochs are defined by more localized geological and biological changes.

(5) Age: The smallest division of time on the Geological Time Scale. Ages represent relatively brief periods, often defined by specific fossil or rock layers.

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Central Idea

• A team of scientists from IIT Kharagpur has discovered evidence of exceptionally high annual rainfall during the volcanic activity that formed the Deccan Traps in India around 66 million years ago.
• Using a new technique called Nanoscale Secondary Ion Mass Spectrometry (NanoSIMS), the researchers analyzed the isotopic composition of fossil trees from the Cretaceous period.
• They determined the isotopic composition of the rainfall-derived lake water.

Nanoscale Secondary Ion Mass Spectrometry (NanoSIMS)

• NanoSIMS is an advanced analytical technique to determine the composition and distribution of elements and isotopes at a microscopic scale.
• It allows for high-resolution imaging and quantitative analysis of samples.
• The technique involves bombarding the sample surface with a focused beam of primary ions.
• This causes the ejection of secondary ions from the sample surface.
• The secondary ions are collected and analyzed using a mass spectrometer.
• The mass spectrometer separates the ions based on their mass-to-charge ratio and measures their abundance.

Analysis and Findings

• New Technique: The team used Nanoscale Secondary Ion Mass Spectrometry to analyze oxygen isotopes in fossil trees and measure the isotopic composition of the lake water derived from rainfall.
• Depleted Oxygen Isotopes: The analysis revealed depleted oxygen isotope values, indicating higher tropical rainfall in India during the terminal Cretaceous period.
• Link to Paleoclimatic Changes: The increase in rainfall closely corresponded to changes in paleo-atmospheric carbon dioxide levels, suggesting a potential underlying link between the two.

Implications and Comparison

• Atmospheric Carbon Dioxide Concentration: The eruption of Deccan Trap lavas released a significant amount of carbon dioxide, raising atmospheric levels to as high as 1,000 ppm.
• Comparison to Modern Rainfall: The data from fossil trees indicated an annual rainfall of 1,800-1,900 mm, exceeding the average modern rainfall of 1,000-1,200 mm in most parts of peninsular India.
• Climate Change Predictions: The findings align with predictions made by the Intergovernmental Panel on Climate Change (IPCC) for extreme warming scenarios, suggesting a correlation between high carbon dioxide levels and increased rainfall.

Climate Models and Future Projections

• Rising Carbon Dioxide Levels: Fossil fuel emissions have raised carbon dioxide levels from 280 ppm to about 420 ppm in 2023.
• Impact on Rainfall: Climate models indicate that doubling carbon dioxide levels will intensify atmospheric circulation and subsequently increase rainfall.
• IPCC AR6 Report: The report warns of a significant increase in the wettest day precipitation and tropical cyclone-associated rainfall if carbon dioxide emissions continue to rise unabated.

Conclusion

• The study provides evidence of high rainfall during the volcanic activity that formed the Deccan Traps in India millions of years ago.
• The findings suggest a correlation between elevated carbon dioxide levels and increased rainfall, supporting predictions made by climate models for future climate change scenarios.

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Central Idea

• One intriguing phenomenon recently discovered is the presence of a significant “gravity hole” in the Indian Ocean, where the gravitational pull is notably weaker.
• Recent research sheds light on the possible causes behind this anomaly.

What is a Gravity Hole?

• A “gravity hole” refers to a region on Earth where the gravitational pull is significantly weaker compared to the surrounding areas or the global average.
• It is characterized by a dip or low gravity anomaly.
• In such areas, the sea level may be lower than average due to the weaker gravitational force acting upon the water.
• This term is often used to describe specific locations, such as the Indian Ocean geoid low (IOGL), where the gravitational pull is notably diminished compared to nearby regions.
• The exact causes of gravity holes can vary and may involve factors such as variations in the Earth’s mass distribution or underlying geological features.

What is Indian Ocean Geoid Low (IOGL)?

• It is located approximately 1,200 kilometers southwest of the southernmost tip of India.
• IOGL is an area in the Indian Ocean where the sea level is about 106 meters below the global average.

Unraveling the Causes of IOGL

• Discovering the Anomaly: Geophysicist Felix Andries Vening Meinesz first identified the IOGL during a survey in 1948. Since then, it has been confirmed by subsequent ship-based experiments and satellite measurements.
• Ancient Ocean Hypothesis: Researchers from the Indian Institute of Science conducted computer-simulated models spanning 140 million years. They discovered remnants of an ancient ocean, located approximately 965 kilometers below the Earth’s crust, just beneath Africa.
• Molten Rock Plumes: The simulations revealed molten rock plumes below Africa, potentially caused by tectonic plates subducting into the mantle. These plumes are believed to be a contributing factor to the IOGL.
• Possible origination: Researchers said that the IOGL comprises slabs from the Tethys Sea, a long-lost sea that plunged into the depths of the planet millions of years ago. Tethys Sea, which once separated the supercontinents of Gondwana and Laurasia is believed to have perturbed the African Large Low Shear Velocity province.

Future Perspectives

• Lack of Seismic Evidence: While the simulated models suggest the presence of molten rock plumes beneath the Indian Ocean, seismographic evidence has yet to confirm their actual existence.
• Additional Factors at Play: The researchers emphasize that other factors contributing to the gravitational anomaly in the Indian Ocean need to be further explored before reaching a definitive conclusion.
• Further Research: Continuation of studies, including seismic surveys and detailed modelling, is necessary to gain a comprehensive understanding of the IOGL and its causes.

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Central Idea

• The summer solstice, also known as the longest day of the year, occurs on June 21st for those living north of the Equator.
• This article explores the significance of the summer solstice, the reasons behind its occurrence, and the effects it has on different parts of the world.

What is Summer Solstice?

• The summer solstice is the moment when the Earth’s axial tilt is most inclined towards the Sun.
• It occurs annually on or around June 21st in the Northern Hemisphere.
• During the summer solstice, the Sun follows its highest and longest path across the sky.
• This results in an extended duration of daylight hours, making it the longest day of the year.

Factors Influencing the Summer Solstice

• Earth’s Axial Tilt: The Earth’s axis is tilted relative to its orbit around the Sun, at an angle of approximately 23.5 degrees.
• Tropic of Cancer: The summer solstice takes place when the Sun is directly over the Tropic of Cancer, located at 23.5 degrees north latitude.
• Seasonal Variations: The tilt of the Earth’s axis causes different latitudes to receive varying amounts of sunlight throughout the year.

Sunlight Distribution in the Hemispheres

• The Northern Hemisphere receives the maximum amount of sunlight during the summer solstice, typically on June 20, 21, or 22.
• In contrast, the Southern Hemisphere experiences its peak sunlight during the winter solstice, which occurs on December 21, 22, or 23.

Cultural Significance and Celebrations

• The summer solstice holds cultural and religious significance in various civilizations throughout history.
• Festivals and rituals often commemorate this astronomical event, symbolizing the triumph of light and fertility.
• People around the world celebrate the summer solstice through festivals, bonfires, music, dancing, and outdoor activities.
• Notable celebrations include the Summer Solstice Stonehenge Festival in England and the Midnight Sun Festival in Norway.

Back2Basics: Solstices and Equinoxes

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Central Idea: The article discusses the Palghat (Palakkad) Gap, a significant corridor in the Western Ghats of India. It provides information about the geological origin of the gap.

What is Palghat Gap?

• The Palghat Gap is a 40 km wide corridor in the Western Ghats, known for its steep hills and serving as a gateway to Kerala.
• It is a crucial passage for roads and railways connecting Coimbatore and Palakkad.
• The Bharathappuzha River flows through the Palghat Gap.
• The vegetation in the gap is classified as dry evergreen forest, different from the tropical rainforests of the Western Ghats.
• The Palghat Gap marks a distinct divide in the flora and fauna of the region.

Geological origin of the Palghat Gap

• The Palghat Gap is a geological shear zone running from east to west.
• Shear zones are weak regions in the Earth’s crust, occasionally causing tremors in the Coimbatore region.
• The formation of the Palghat Gap occurred when the continental shelves shifted after the separation of Australia and Africa from the Gondwana landmass.
• India and Madagascar were connected until volcanic activity led to their split, with a similar gap called the Ranotsara Gap in Madagascar.

Biogeographic distinctions and ancient history

• The biogeographic distinctions in species north and south of the Palghat Gap may be attributed to an ancient river or an incursion of the sea in the distant past.
• Elephant populations on the Nilgiris side of the gap have different mitochondrial DNA from elephants in the Anamalai and Periyar sanctuaries.
• DNA analysis of the White-bellied Shortwing, an endemic bird species, shows divergence between populations in the Nilgiris and the Anamalai regions.

Biodiversity south of the Palghat Gap

• The southern region of the Western Ghats, located south of the Palghat Gap, exhibits high species richness and phylogenetic diversity.
• A recent study reports over 450 tree species, including ancient species like Magnolia champaca, dating back 130 million years.
• The warm weather and moist air of the southern Western Ghats support a diverse range of life, making it an island refuge during cycles of ice ages and droughts.
• The southern Western Ghats receive rainfall more evenly throughout the year compared to the northern region.

Back2Basics: Western Ghats

• The Western Ghats, also known as the Sahyadri mountain range, is a UNESCO World Heritage Site and one of the 36 biodiversity hotspots in the world.
• It spans an area of 160,000 sq. km. and stretches for 1,600 km parallel to the western coast of the Indian peninsula, passing through the states of Gujarat, Maharashtra, Goa, Karnataka, Kerala, and Tamil Nadu.

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Central Idea: Scientists have reported finding 19,325 new seamounts after poring through new high-resolution data. A study had already mapped 24,000 seamounts across the world’s oceans.

Why study this?

• The recent discovery of new seamounts was made possible by advancements in altimetry for gravity-field mapping, which improved spatial coverage.
• The CryoSat-2, Envisat, Jason-1 geodetic missions, and the SARAL satellite developed by India and France contributed to these advancements.

What are Seamounts?

• Seamounts are underwater mountains formed through volcanic activity.
• They are recognised as hotspots for marine life.
• Most seamounts are formed near mid-ocean ridges, intraplate hotspots, and oceanic island chains with volcanic and seismic activity called island arcs.
• They can be active, extinct or dormant volcanoes.

Importance of Seamounts

• Seamounts provide information about the mantle’s composition and how tectonic plates evolve as they are formed when molten rock comes up from below the tectonic plates.
• Oceanographers study seamounts to understand their influence on how water circulates and absorbs heat and carbon dioxide.
• Seamounts are home to diverse biological communities as they can cause localised ocean upwelling, which brings nutrient-rich water from deep within the ocean to the surface.

How were they mapped?

• Surveyors map seamounts using either echo sounders or multibeam sonar on ships for topographic mapping or using satellite altimetry for gravity-field mapping.
• The hi-res maps produced by multibeam sonar mapping are often incomplete, whereas the low-res maps produced by satellite altimetry have better coverage.

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A ‘hybrid’ solar eclipse called the Ningaloo Eclipse recently happened on April 20, 2023.

Ningaloo ‘Hybrid’ Solar Eclipse

• It was a rare astronomical event that occurred on April 20, 2023.
• The Moon passed directly between the Sun and the Earth, casting a shadow on a narrow strip of land in Western Australia.
• It was a “hybrid” eclipse, starting as an annular eclipse and transitioning into a total eclipse.
• The path of the eclipse crossed over the Ningaloo Reef, a world heritage site in Western Australia.
• It offered a unique opportunity to view the eclipse against the backdrop of the reef and the Indian Ocean.

How rare are such events?

• During a solar eclipse, the Moon passes between the Sun and Earth, casting a shadow on Earth’s surface.
• However, solar eclipses do not occur every month because the Moon’s orbit is tilted by about 5 degrees relative to Earth’s orbit around the Sun.
• Therefore, the Moon’s shadow usually misses Earth, but occasionally the alignment is just right for a solar eclipse to occur.
• In the case of the Ningaloo Hybrid Solar Eclipse, the alignment was such that the Moon was at the right distance from Earth to create both an annular and a total eclipse as it moved across the Sun.
• This type of eclipse is quite rare, occurring only about once every 400 years.

Back2Basics:

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