Changes to Geophysical: news and updates

What is the News?

The world’s largest existing iceberg has been found in Antarctica. It has been named as A-76 by scientists.

About A-76 Iceberg:

• A-76 Iceber has been spotted in the satellite images captured by the European Space Agency’s Copernicus Sentinel-1 mission.
• Formation: The iceberg has been formed after it broke away from Antarctica’s Ronne Ice Shelf. It is now floating freely in the Weddell Sea, a large bay in western Antarctica.
• Features: The iceberg is shaped like a giant ironing board. It is measured around 170 km in length and 25 km in width. This makes the A-76 to become slightly larger than the Spanish island of Majorca.
• The Largest Existing Iceberg: A-76 is now designated as the largest existing iceberg on the planet. It surpassed the A-23A (It is also floating in the Weddell Sea).
• Significance: Once this iceberg melts, it will not lead to a sea-level rise because it was part of a floating ice shelf. It is just like a melting ice cube doesn’t increase the level of the water in the glass.
  • This makes the icebergs like this different from glaciers or ice sheets. Glaciers or ice sheets found on land, and they raise global sea levels when they break off into the ocean and melt.

Source: TOI

Finance Ministry grants “infrastructure status for convention centres”

What is the News?

Indonesia’s Mount Sinabung has erupted releasing a massive column of volcanic ash and smoke up to 3,000 metres(3 km) into the sky.

About Mount Sinabung:

• Mount Sinabung is located in North Sumatra in Indonesia. It is among more than 130 active volcanoes in Indonesia. (Indonesia is prone to seismic upheaval due to its location on the Pacific’s Ring of Fire).
• The volcano was dormant for 400 years before exploding in 2010. It exploded again in 2014 and 2016.

About Ring of Fire:

• The Ring of Fire also referred to as the Circum-Pacific Belt is a path along the Pacific Ocean. Its characteristics include active volcanoes and frequent earthquakes.
• Boundaries: It traces boundaries between several tectonic plates including Pacific, Cocos, Indian-Australian, Nazca, North American and Philippine Plates.
• Significance:
  • 75% of Earth’s volcanoes i.e. more than 450 volcanoes are located along the Ring of Fire.
  • 90% of Earth’s earthquakes occur along its path.
• The abundance of volcanoes and earthquakes along the Ring of Fire is due to the frequent movement of tectonic plates in this area.

What is Volcano?

• A volcano is an eruption in the earth’s crust through which the lava, volcanic ash and gases escape to release pressure.

Why Volcanic Eruption takes place?

• Magma is a thick flowing substance. Its formation happens during the melting of Earth’s crust and mantle.
• Volcanic eruption takes place when magma rises to the surface.
• As magma is lighter than rock, it is able to rise through vents and fissures on the surface of the earth. After the eruption, the magma is called lava.

Types of Volcanoes: Volcanoes are classified as active, dormant, or extinct:

• Active volcanoes have a recent history of eruptions. They are likely to erupt again.
• Dormant volcanoes have not erupted for a very long time but may erupt at a future time.
• Extinct volcanoes are not expected to erupt in the future.

Risk From Volcanic Eruptions:

• The most common cause of death from a volcano is suffocation. People with respiratory conditions such as asthma and other chronic lung diseases are susceptible to suffocation.
• People living close to the volcano or in low-lying downwind areas are also at higher risk in case of an explosion. As the ash may be coarse-grained and abrasive, even small particles can scratch the surface of the eyes.
• Further, volcanic eruptions can result in additional threats to health such as floods, mudslides, power outages, drinking water contamination and wildfires.

Source: Indian Express

What is the News? Researchers at Sweden’s University of Gothenburg releases a new finding related to the melting of the Thwaites Glacier. They found that the melting was worse than previously thought.

About Thwaites Glacier:

• Thwaites Glacier is a 120 km wide, fast-moving glacier located in Antarctica.
• Size: Because of its size (1.9 lakh square km), it contains enough water to raise the world sea level by more than half a meter.
• Melting: Its melting already contributes 4% to global sea-level rise each year. It is estimated that it would collapse into the sea in 200-900 years.
  • Studies have found the amount of ice flowing out of it has nearly doubled over the past 30 years.
• Significance: Thwaites Glacier is important for Antarctica as it slows the ice behind it, from freely flowing into the ocean. However, because of the risk it faces — and poses — Thwaites is often called the Doomsday Glacier.

About the Study:

• Gothenburg study used an uncrewed submarine called “Ran” to go under the Thwaites’ glacier front to make observations.
• The researchers measured the strength, temperature, salinity, and oxygen content of the ocean currents that go under the glacier.
• Findings: The study found that warm water is approaching the glacier from all sides. It is impacting the locations where the ice connects to the seabed and where the ice sheet finds stability. This has the potential to make things worse for Thwaites, whose ice shelf is already retreating.

Earlier Studies:

• Cavity in the Glacier: A 2019 study had discovered a fast-growing cavity in the Thwaites’ glacier. It’s size was roughly two-thirds of the area of Manhattan.
  • A cavity is created by relatively warm ocean water melting the ice shelf. As the glacier becomes exposed to more warm-water currents, the ice will probably melt faster.
• Detection of Warm Water at Grounding Line: In 2020, researchers from New York University(NYU) detected warm water at Thwaites’ “grounding zone” or “grounding line”.
  • The Grounding Line is the place below a glacier at which the ice transitions between resting fully on bedrock and floating on the ocean as an ice shelf. The location of the line is a pointer to the rate of retreat of a glacier.
  • When glaciers melt and lose weight, they float off the land where they used to be situated. When this happens, the grounding line retreats. That exposes more of a glacier’s underside to seawater, increasing the likelihood it will melt faster.
  • This results in the glacier speeding up, stretching out, and thinning, causing the grounding line to retreat ever further.

Source: Indian express

What is the News?

Parts of Uttarakhand witnessed massive flooding due to Glacial Lake outburst.

 What is Glacial Lake Outburst Floods(GLOF)?

• It is a type of outburst flood. It occurs when water dammed by a glacier is released. In other words, it’s an outburst that happens when a dam containing a glacial lake fails.

Note: An event similar to a GLOF, where a body of water contained by a glacier melts or overflows the glacier is called a jökulhlaup.

How does GLOF happen?

• Retreating glaciers, like several in the Himalayas, usually result in the formation of lakes at their tips, called proglacial lakes. It is often bound only by sediments and boulders.
• If the boundaries of these lakes are breached, it can lead to large amounts of water rushing down to nearby streams and rivers. It gathers momentum on the way by picking up sediments, rocks, and other material, and resulting in flooding downstream.

Features of GLOF: The three main features are:

• They involve sudden (and sometimes cyclic) releases of water.
• They tend to be rapid events, lasting hours to days.
• Furthermore, they result in large downstream river discharges (which often increase by an order of magnitude).

Causes behind GLOFs

The boundaries of glacial lakes breach due to multiple reasons. Like,

1. A buildup of water pressure or structural weakness of boundary due to an increase in the flow of water.
2. An earthquake (Tectonic) or cryoseism (non-tectonic seismic event of the glacial cryosphere) can also cause GLOF. During this, the boundary of the glacial lake will collapse suddenly and release the water in the glacial lake.
3. An avalanche of rock or heavy snow: During this, the water in the glacial lake might be displaced by the avalanche.
4. Volcanic eruptions under the ice can also cause GLOF. These volcanic eruptions might displace the boundary or increase the pressure on glacial lake or both.
5. Heavy rainfall/melting of snow: This can lead to massive displacement of water in a glacial lake.
6. Long-term dam degradation can also induce GLOF.
7. Other reasons such as the collapse of an adjacent glacial lake, etc.

What are Glaciers?

• Glaciers are made up of fallen snow. It compresses into large, thickened ice masses over a period of time. They are formed when snow remains in one location long enough to transform into ice.
• Where are Glaciers found? Glaciers are found on every continent except Australia. Some are hundreds of thousands of years old. A large cluster of glaciers are in the Himalayas, which are part of India’s long northern border.

Source: The Hindu