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Subject: Geography

  • Earth’s seismic noise levels

    Scientists at the British Geological Survey (BGS) reported a change in the Earth’s seismic noise and vibrations amid the coronavirus lockdown. This change has been monitored through a space-based seismograph.

    Ever heard of space-based monitoring of seismic activities?  This topic creates a scope for potential prelims question…

    What is seismic noise?

    • In geology, seismic noise refers to the relatively persistent vibration of the ground due to a multitude of causes.
    • It is the unwanted component of signals recorded by a seismometer– the scientific instrument that records ground motions, such as those caused by earthquakes, volcanic eruptions, and explosions.
    • This noise includes vibrations caused due to human activity, such as transport and manufacturing, and makes it difficult for scientists to study seismic data that is more valuable.
    • Apart from geology, seismic noise is also studied in other fields such as oil exploration, hydrology, and earthquake engineering.

    How are vibrations generated?

    • We measure ground vibrations from earthquakes using seismometers.
    • These are incredibly sensitive so they also pick up other sources of vibration too, including human activity, such as road traffic, machinery and even people walking past.
    • All these things generate vibrations that propagate as seismic waves through the Earth.

    Reasons for the decline

    • Due to the enforcement of lockdown measures around the world to tackle the novel coronavirus pandemic, the Earth’s crust has shown reduced levels of vibration.

    How do the reduced noise levels help scientists?

    • The seismic noise vibrations caused by human activity are of high frequency (between 1-100 Hz), and travel through the Earth’s surface layers.
    • Usually, to measure seismic activity accurately and reduce the effect of seismic noise, geologists place their detectors 100 metres below the Earth’s surface.
    • However, since the lockdown, researchers were able to study natural vibrations even from surface readings, owing to lesser seismic noise.
    • Due to lower noise levels, scientists are now hoping that they would be able to detect smaller earthquakes and tremors that had slipped past their instruments so far.

     

  • Armed Forces: their role during crisis, procedures for requisition

    As the Army moves in to take over the COVID-19 quarantine facility in Delhi, the procedure for calling the armed forces to help the civil administration is in the spotlight.

    Requisition the Army

    • The regulations permit civil authorities to requisition the Army for controlling law and order, maintaining essential services, assisting during natural calamities such as earthquakes, and any other type of help that may be needed by the civil authorities.
    • The procedure for requisitioning armed forces is governed under several guidelines including:
    1. ‘Aid to Civil Authorities’ under the guidelines laid in Instructions on Aid to the Civil Authorities by the Armed Forces, 1970;
    2. Regulations for the Army, Chapter VII, Paragraphs 301 to 327 and
    3. Manual of Indian Military Law, Chapter VII

    How is Army invited?

    • Civil administration requests the Local Military Authority for assistance, for the maintenance of law and order, maintenance of essential services, disaster relief and other types of assistance.
    • Armed forces can be asked to provide troops and equipment for a flag march, rescue and relief, evacuation, and immediate aid.
    • The current case of checking the spread of COVID-19 is different, as the medical aspect is predominant.
    • These resources are being controlled centrally and judiciously, because of the requirement of doctors, equipment and facilities.

    Why need Armed forces in such situations?

    • Besides the specialised medical resources, which are centrally controlled, the local units are prepared for maintenance of law and order, crowd control, curfew in sensitive areas etc.
    • Moreover provision of essential supply of electricity and water, restoration of essential services, emergency feeding and shelter, prevention of panic, prevention of theft and loot are other areas of concerns.
    • During such multi-faceted challenges, local authorities have shortfall to perform all such functions.

    In such situations, what happens to the armed forces’ primary role?

    • Providing aid to civil authorities, as and when called upon to do so, is a secondary task for the armed forces.
    • It cannot replace the primary role of ensuring external security and operational preparedness.

    Is there a ceiling on such deployment?

    • No, there is no such ceiling either of a duration of deployment or on the number of armed forces personnel that can be deployed to aid civil authority.
    • The National Crisis Management Committee (NCMC), headed by the cabinet secretary, is the final authority.

    Are there any templates or instances from the past that are applicable here?

    • The current situation is different from earlier cases such as tsunami or super-cyclone, which were natural disasters.
    • The major difference is that specialists are the key in the current situation, and their tasks cannot be performed by general duty soldiers.

    Who pays for the costs incurred?

    • The civil administration is responsible for the costs incurred by the armed forces in these roles.
    • The cost of assistance provided by the Armed Forces is recovered in accordance with the instructions contained in ‘Instructions on Aid to Civil Authorities by the Armed Forces 1970’.

    What is the role of the National Disaster Management Authority?

    • NDMA is involved in secondary follow-ups by the Home Ministry and is not very actively involved in the current case.
    • The roles of the Ministries of Health, Home, Civil Aviation and Defence are predominant in this case.
    • The armed forces are aligned with them at the apex level viz NCMC.
    • The directions are followed by execution-level coordination which is done by respective secretaries in the government.

  • Prime Minister’s National Relief Fund (PMNRF)

    Keeping in view the novel coronavirus crisis across the country, various govt. employees, celebrities and political dignitaries are open-heartedly contributing to the PM’s National Relief Fund (PMNRF) to help combat the disease.

    PM’s National Relief Fund (PMNRF)

    • In pursuance of an appeal by the then PM, Pt. Nehru in January, 1948, the Prime Minister’s National Relief Fund (PMNRF) was established with public contributions.
    • It was aimed to assist displaced persons from Pakistan.
    • The resources of the PMNRF are now utilized primarily to render immediate relief to families of those killed in natural calamities like floods, cyclones and earthquakes, etc. and to the victims of the major accidents and riots.
    • Assistance from PMNRF is also rendered, to partially defray the expenses for medical treatment like heart surgeries, kidney transplantation, cancer treatment and acid attack etc.
    • The fund consists entirely of public contributions and does not get any budgetary support.

    Legal status

    • PMNRF has not been constituted by the Parliament.
    • The fund is recognized as a Trust under the Income Tax Act and the same is managed by PM or multiple delegates for national causes.

    Donations

    • PMNRF accepts only voluntary donations by individuals and institutions.
    • Contributions flowing out of budgetary sources of Government or from the balance sheets of the public sector undertakings are not accepted.
    • Conditional contributions, where the donor specifically mentions that the amount is meant for a particular purpose, are not accepted in the Fund.

    Its operation

    • PMNRF operates from the Prime Minister’s Office and does not pay any license fee.
    • PM is the Chairman of PMNRF and is assisted by Officers/ Staff on an honorary basis. Permanent Account Number of PMNRF is AACTP4637Q.

    Tax exemptions

    • PMNRF is exempt under the Income Tax Act, 1961 under Section 10 and 139 for return purposes.
    • Contributions towards PMNRF are notified for 100% deduction from taxable income under section 80(G) of the Income Tax Act, 1961.

  • Explained: Notified Disaster

    The Ministry of Home Affairs has decided to treat COVID-19 as a notified disaster for the purpose of providing assistance under the State Disaster Response Fund (SDRF).

    What is a Disaster?

    According to the Disaster Management Act, 2005 a disaster is defined as-

    • A catastrophe, mishap, calamity or grave occurrence in any area, arising from natural or manmade causes, or by accident or negligence which results in substantial loss of life or human suffering or damage to, and destruction of, property, or damage to, or degradation of, environment, and is of such a nature or magnitude as to be beyond the coping capacity of the community of the affected area.
    • The MHA has defined a disaster as an “extreme disruption of the functioning of a society that causes widespread human, material, or environmental losses that exceed the ability of the affected society to cope with its own resources.

    What is the State Disaster Response Fund?

    • The SDRF is constituted under the Disaster Management Act, 2005 and is the primary fund available with state governments for responses to notified disasters.
    • The Central government contributes 75 per cent towards the SDRF allocation for general category states and UTs, and over 90 per cent for special category states/UTs (which includes northeastern states, Sikkim, Himachal Pradesh and Uttarakhand).
    • For SDRF, the Centre releases funds in two equal instalments as per the recommendation of the Finance Commission.
    • The disasters covered under the SDRF include cyclones, droughts, tsunamis, hailstorms, landslides, avalanches and pest attacks among others.

    The NDRF

    The National Disaster Response Fund, which is also constituted under the Disaster Management Act, 2005 supplements the SDRF of a state, in case of a disaster of severe nature, provided adequate funds are not available in the SDRF.

    Categories of disaster

    • A High Power Committee on Disaster Management was constituted in 1999 to identify disaster categories.
    • It identified 31 disaster categories organised into five major subgroups, which are: water and climate-related disasters, geological related disasters, chemical, industrial and nuclear-related disasters and biological related disasters, which includes biological disasters and epidemics.

    Have there been such instances in the past?

    • In 2018, in view of the devastation caused by the Kerala floods, political leaders in Kerala demanded that the floods be declared a “national calamity”.
    • As of now, there is no executive or legal provision to declare a national calamity.
    • In 2001, the National Committee on Disaster Management under then PM was mandated to look into the parameters that should define a national calamity.
    • However, the committee did not suggest any fixed criterion.
    • In the past, there have been demands from states to declare certain events as natural disasters, such as the Uttarakhand flood in 2013, Cyclone Hudhud in Andhra Pradesh in 2014, and the Assam floods of 2015.

  • Earth’s spin has slowed over time

     

    Earth spun 372 times a year 70 million years ago, compared to the current 365. This means the day was 23½ hours long, compared to 24 today.

    Faster Earth in the olden days

    • It has long been known that Earth’s spin has slowed over time.
    • Previous climate reconstructions, however, have described long-term changes over tens of thousands of years.
    • The new study looked at daily and annual variations in the mollusc shell.

    About the Mollusc

    • A mollusc is an invertebrate of a large phylum which includes snails, slugs, mussels, and octopuses. They have a soft unsegmented body and live in aquatic or damp habitats, and most kinds have an external calcareous shell.
    • The ancient mollusc, Torreites Sanchez, belonged to an extinct group called rudist clams.
    • At 70 million years ago, it belonged to the Late Cretaceous — it was around the time this epoch ended, some 65 million years ago, that dinosaurs went extinct.

    How did researchers conclude this variation?

    • Torreites sanchezi grew very fast, laying down daily growth rings.
    • Using lasers on a single individual, scientists sampled tiny slices and counted the growth rings accurately.
    • This allowed them to determine the number of days in a year 70 million years ago, and more accurately calculate the length of a day.

    Significance of the research

    • It is important to note that the period of Earth’s orbit has remained the same. In other words, one year 70 million years ago was as long as one year today.
    • However, if there were a calendar then, the year would have been 372 “days” long, with each “day” half-an-hour shorter than one day today.
    • Today, Earth’s orbit is not exactly 365 days, but 365 days and a fraction, which is why our calendars have leap years, as a correction.

    The Moon’s retreat

    • Friction from ocean tides, caused by the Moon’s gravity, slows Earth’s rotation and leads to longer days.
    • And as Earth’s spin slows the Moon moves farther away at 3.82 cm per year.
    • If this rate is projected back in time, however, the Moon would be inside the Earth only 1.4 billion years ago.
    • This new measurement, in turn, informs models of how the Moon formed and how closes it has been to Earth over their 4.5-billion-year gravitational relationship.

  • [pib] Effects of Himalayan slip on its Hydrology

    Researchers from the Indian Institute of Geomagnetism have found the mighty Himalayas subside and move up depending on the seasonal changes in groundwater.

    Tectonic activity and groundwater

    • The Himalayan foothills and the Indo-Gangetic plain are sinking because its contiguous areas are rising due to tectonic activity associated with landmass movement or continental drift.
    • The new study shows that subsidence and uplift are found to be associated with seasonal changes in groundwater, apart from the normal, common reasons.
    • Water acts as a lubricating agent, and hence when there is water in the dry season, the rate of the slip of the fault in this region is reduced.
    • In the Himalaya, seasonal water from glaciers, as well as monsoon precipitation, plays a key role in the deformation of the crust and the seismicity associated with it.
    • The subsidence rate is associated with groundwater consumption.

    Findings of the study

    • The researchers have made the combined use of GPS and Gravity Recovery And Climate Experiment (GRACE) data, which has made it possible for them to quantify the variations of hydrologic mass.
    • The GRACE satellites, launched by the US in 2002, monitor changes in water and snow stores on the continents.
    • The combined data suggest a 12% reduction in the rate of the subsurface slip. This slip refers to how fast the fault is slipping relative to the foot and hanging wall.
    • The slip occurs at the Main Himalayan Thrust (MHT), due to hydrological variations and human activities, over which there is the periodic release of accumulated strain.

    About GRACE Mission

    • The Gravity Recovery and Climate Experiment (GRACE) was a joint mission of NASA and the German Aerospace Center.
    • Twin satellites took detailed measurements of Earth’s gravity field anomalies from its launch in March 2002 to the end of its science mission in October 2017.
    • By measuring gravity anomalies, GRACE showed how mass is distributed around the planet and how it varies over time.

     

  • Explained: Cycle 25/ Solar Cycle

     

     

    The sunspots identified by researchers from IISER Kolkata herald the start of a new solar cycle called Cycle 25.

    What are Sunspots?

    • Sunspots are temporary phenomena on the Sun’s photosphere that appear as spots darker than the surrounding areas. They are relatively cooler spots on the Sun’s surface.
    • They are regions of reduced surface temperature caused by concentrations of magnetic field flux that inhibit convection.
    • Sunspots usually appear in pairs of opposite magnetic polarity with a leader and a follower.

    What is Solar Cycle?

    • From our safe distance of about 148 million km, the Sun appears to be sedate and constant. However, huge solar flares and coronal mass ejections spew material from its surface into outer space.
    • They originate from sunspots, an important phenomenon that people have been following for hundreds of years. They originate deep within the Sun and become visible when they pop out.
    • Their number is not constant but shows a minimum and then rises up to a maximum and then falls again in what is called the solar cycle.
    • Every 11 years or so, the Sun’s magnetic field completely flips. This means that the Sun’s north and south poles switch places. Then it takes about another 11 years for the Sun’s north and south poles to flip back again.
    • So far, astronomers have documented 24 such cycles, the last one ended in 2019.

    How do they occur?

    • Given the high temperatures in the Sun, matter exists there in the form of plasma, where the electrons are stripped away from the nuclei.
    • The Sun is made of hot ionized plasma whose motions generate magnetic fields in the solar interior by harnessing the energy of the plasma flows.
    • This mechanism is known as the solar dynamo mechanism (or magnetohydrodynamic dynamo mechanism).
    • Simply stated, it is a process by which kinetic energy of plasma motions is converted to magnetic energy, which generates the magnetised sunspots, giving rise to the solar cycle..
    • Because of the nature of the solar dynamo, the part of its magnetic field that gives rise to sunspots reverses direction when it moves from one solar cycle to another.
    • This can be inferred by observing when the relative orientation of the sunspot pairs flips.

    Features

    • The solar cycle affects activity on the surface of the Sun, such as sunspots which are caused by the Sun’s magnetic fields. As the magnetic fields change, so does the amount of activity on the Sun’s surface.
    • One way to track the solar cycle is by counting the number of sunspots.
    • The beginning of a solar cycle is a solar minimum, or when the Sun has the least sunspots. Over time, solar activity—and the number of sunspots—increases.
    • The middle of the solar cycle is the solar maximum, or when the Sun has the most sunspots. As the cycle ends, it fades back to the solar minimum and then a new cycle begins.
    • Giant eruptions on the Sun, such as solar flares and coronal mass ejections, also increase during the solar cycle. These eruptions send powerful bursts of energy and material into space.

    Impacts of Solar Cycle

    • This activity has effects on Earth. For example, eruptions can cause lights in the sky, called aurora, or impact radio communications. Extreme eruptions can even affect electricity grids on Earth.
    • Solar activity can affect satellite electronics and limit their lifetime.
    • Radiation can be dangerous for astronauts who do work on the outside of the International Space Station.
    • Forecasting of the solar cycle can help scientists protect our radio communications on Earth, and help keep satellites and astronauts safe.

    Start of cycle 25

    • Following a weakening trend in activity over the last few cycles, there were predictions that the Sun would go silent into a grand minimum in activity, with the disappearance of cycles.
    • However, a team from IISER Kolkata has shown that there are signs that cycle 25 has just begun.
    • They used the data from the instrument Helioseismic and Magnetic Imager aboard NASA’s space-based Solar Dynamics Observatory for their calculations.

    Why is this so important to us on earth?

    • After all the sunspots look small and are hardly even visible to us. Contrary to this, sunspot activity may be correlated with climate on earth.
    • In the period between 1645 and 1715, sun spot activity had come to a halt on the Sun – a phenomenon referred to as the Maunder minimum.
    • This coincided with extremely cold weather globally. So sunspots may have a relevance to climate on earth.
    • Such links are tenuous, but definitely solar activity affects space weather, which can have an impact on space-based satellites, GPS, power grids and so on.

  • Solar Storms

     

    According to a research, sudden releases of high-energy particles from the sun, called solar storms, can mess with the navigational ability of gray whales, causing them to strand on land.

    Solar storms

    • Solar storms are a variety of eruptions of mass and energy from the solar surface.
    • Flares, prominences, sunspots, coronal mass ejections are the common harbingers of solar activity, as are plages and other related phenomena seen at other wavelengths.

    Impact on Whales

    • Solar storms have the potential to modify geomagnetic field and disrupt magnetic orientation behaviour of animals, hampering their navigation during long periods of migration.
    • They disrupt earth’s magnetic field — and the whales’ navigational sense.
    • The radio frequency noise created by the solar outburst affects the whales’ senses in a way that prevents them from navigating at all.

  • Yongle Blue Hole (YBH)

     

    Carbon more than 8,000 years old has been found inside the world’s deepest blue hole — the Yongle Blue Hole (YBH).

    Yongle Blue Hole (YBH)

    • The deepest known marine cavern is the Yongle blue hole, which measures roughly 300 metres from top to bottom.
    • Blue holes are marine caverns filled with water and are formed following dissolution of carbonate rocks, usually under the influence of global sea level rise or fall.
    • Its waters are mostly isolated from the surrounding ocean and receive little fresh water from rainfall, making it a rare spot to study the chemistry of oxygen-deprived marine ecosystems.
    • What distinguishes them from other aquatic caverns is that they are isolated from the ocean and don’t receive fresh rainwater.
    • They are generally circular, steep-walled and open to surface.

    Significance of YBH

    • YBH has a depth of 300 metres, far deeper than the previously recorded deepest blue hole, Dean’s Blue Hole in Bahamas, which had a depth of 202 metres.
    • However, like most blue holes, it is anoxic i.e. depleted of dissolved oxygen below a certain depth. This anaerobic environment is unfavorable for most sea life.
    • Such anoxic ecosystems are considered a critical environmental and ecological issue as they have led to several mass extinctions.
    • Concentrations of carbon, usually found in deep marine holes like YBH, provide a natural laboratory to study carbon cycling and potential mechanisms controlling it in the marine ecosystem.
    • The transition from aerobic to anaerobic environment adversely affects the biogeo-chemistry of the ocean.

  • Why do we have Leap Years?

     

    The year 2020 is a ‘leap year’, meaning the month of February will have 29 days instead of 28, and the total number of days will be 366 instead of 365. This was also the case in 2016, and 2024 will again be a leap year.

    Leap Years

    • A calendar is meant to correspond to the Earth’s seasons.
    • For this, the number of days in a calendar needs to match the time required by the Earth to orbit the Sun.
    • The time required by the Earth to complete its orbit around the Sun is approximately 365.242 days. But years are usually only 365 days.
    • To adjust for the extra 0.242 days in the orbital period, which becomes almost one full day in four years, the calendar adds an extra day once every four years.
    • This approximates the time to 365.25 days, which is close to the actual 365.242 days.

    But is that not inaccurate?

    • Yes, it is. And further adjustments are made to the Gregorian calendar, the calendar we follow today.
    • The Gregorian calendar was introduced in 1582. Before that, the calendar followed was the Julian calendar, introduced in 45 BC.
    • The calendars were different in their treatment of leap years.
    • The Julian calendar had leap days every four years, but since it still did not accurately conform to the Earth’s precise orbit time, it kept falling behind with respect to natural seasons over the centuries.
    • By the 16th century, the Julian calendar had fallen out of tune with the natural seasons by almost 10 days.
    • To correct this discrepancy, Pope Gregory XIII in 1582 decreed that the day of October 4 that year would be followed directly by October 15 – thus covering up the error.
    • The Pope also modified the leap year system in the Julian calendar. That new system came to be known as the Gregorian calendar.

    What is the new system?

    • In the Gregorian calendar, a century year (a year ending with 00) is not a leap year, even though it is a multiple of 4. Thus, the year 2100 will not be a leap year.
    • But even this does not provide total accuracy. To ensure that, some century years remain leap years. In the Gregorian calendar, leap years include those century years which are exactly divisible by 400.
    • Thus, 2000 remained a leap year even though it ended with 00.
    • The Gregorian calendar reduces the margin of error under the Julian calendar, thus keeping days more in tune with seasons.