Test: Interior of the Earth - 2 - Humanities/Arts MCQ

The correct answer is option 2 i.e Andaman Islands.
The Andaman Islands have an active volcano i.e Barren Islands.

Difference between Active, Dormant, and Extinct Volcanoes is listed below:

Lithosphere: Lithosphere, rigid, rocky outer layer of the Earth, consisting of the crust and the solid outermost layer of the upper mantle. It extends to a depth of about 100 km.

Benioff zone: A dipping planar (flat) zone of earthquakes that is produced by the interaction of a downgoing oceanic crustal plate with a continental plate.

Bedrock: The hard area of rock in the ground that holds up the loose soil above.
Moho: The Moho is the boundary between the crust and the mantle in the earth. This is a depth where seismic waves change velocity and there is also a change in chemical composition. Also termed the Mohorovicic discontinuity.

The correct answer is 111.

• Each latitude on earth is equal to almost 111 kilometers.
• This distance decreases marginally as one travels to poles and increases marginally as one goes towards the equator.

The correct answer is 30.

• The interior structure of the Earth is made up of three main shells the very thin and brittle crust the mantle and the core.
• The earth s radius is 6,370 km.
• Earth is moving about our sun in a very nearly circular orbit. It covers this route at a speed of nearly 30 kilometres per second or 67,000 miles per hour.
• The circumference of a circle is equal to 2 x π x r. So in one year, Earth travels about 584 million miles.
• Earth travels about 1.6 million miles a day.

• The groundwater stored between layers of hard rock below the water table is called aquifer.
• An aquifer is a saturated zone beneath the water table.
• It is a body of porous rock or sediment saturated with groundwater.
• Groundwater enters an aquifer as precipitation seeps through the soil.
• It can move through the aquifer and resurface through springs and wells.
• There are two general types of aquifers: confined and unconfined.
• Confined aquifers have a layer of impenetrable rock or clay above them, while unconfined aquifers lie below a permeable layer of soil. 
• Aquifers are typically made up of gravel, sand, sandstone, or fractured rock, like limestone.
• Water can move through these materials because they have large connected spaces that make them permeable.

Imp. Points

Earth Core:

1. The innermost layer of the earth is known as the core.
2. It is divided into the inner core and the outer core.
3. It comprises a high concentration of nickel and iron.
4. The outer core:
   • The outer core, surrounding the inner core, lies between 2900 km and 5100 km below the earth’s surface.
   • The outer core is composed of iron mixed with nickel (nife) and trace amounts of lighter elements.
5. The Inner Core:
   • The inner core extends from the center of the earth to 5100 km below the earth’s surface.
   • The inner core is generally believed to be composed primarily of iron (80%) and some nickel (nife).
   • Since this layer can transmit shear waves (transverse seismic waves), it is solid. (When P-waves strike the outer core inner core boundary, they give rise to S-waves)

6,371 km is the radius of the earth.

Imp. Points
The interior of the earth can be divided into 3 different layers-

• Crust 
• Mantle
• Core

The crust is the outermost layer of the earth, and the core is the innermost layer of the earth, located at a depth of 2900 km.
The distance to the centre of the Earth is 6,371 kilometres (3,958 mi), the crust is 35 kilometres (21 mi) thick, the mantle is 2855 km (1774 mi) thick.

Imp. Points

• The intensity of an earthquake is measured by the Mercalli Scale.
• It is named after Mercalli, an Italian seismologist.
• It measures the energy released during the earthquake.
• The intensity scale takes into account the visible damage caused by the event.
• The range of intensity scale is from 1-12.

The correct answer is Iron.

• Iron is the second most abundant metal in the earth's crust (5.0%).
• Aluminium is the most abundant metal found in the earth's crust (8.1%).
• Oxygen comprises of 46.6% of the total weight of the earth's crust.

Important Points

• Based on historical seismic activity, the Bureau of Indian Standards has categorized regions in India into four seismic zones: zones II, III, IV and V.
• Of these, the most seismically active area is Zone V and the least active is Zone II. 
• There is a history of devastating earthquakes on the Indian subcontinent.
• The key cause for the high frequency and severity of earthquakes is that the Indian plate is driving into Asia at a rate of roughly 47 mm/year.
• India's geological figures indicate that about 54 percent of the land is prone to earthquakes.
• Research by the World Bank and the United Nations predicts that by 2050, about 200 million urban dwellers in India will be vulnerable to storms and earthquakes.
• The most recent edition of India's seismic zoning map given in India's earthquake-resistant design code [IS 1893 (Part 1) 2002] assigns four degrees of seismicity in terms of zone factors for India.
• In other words, unlike its previous edition, which consisted of five or six zones for the region, India's earthquake zoning map divides India into four seismic zones (Zone 2, 3, 4, and 5).
• According to the new zoning map, the maximum degree of seismicity is predicted in Zone 5, while the lowest level of seismicity is correlated with Zone 2.

Important Points

• The interior of the earth is divided into three parts namely Crust, Mantle, and Core.
• The core is the innermost layer of the earth.
• The radius of the innermost layer(core) is about 3500 km.
• The core is made up of material constituted by nickel and iron.
• The temperature and pressure of the central core are very high.

Important Points

• The most plentiful non-metal in the earth's surface is Oxygen.
• The most plentiful metalloid in the crust of the earth is Silicon.
• O > Si > Al > Fe > Ca are the most abundant elements in the earth crust.

The correct option is Silica and Aluminium.

• In the Outer Crust, the main constituents are Silica and Aluminum whose mean average density is 2.7 g/cm³ and which is collectively called SIAL (i.e. Silica + Aluminum).
• In the Inner Crust, the constituents are Silica and Magnesium.
• The constituents are collectively known as SIMA (Silica + Magnesium). The average mean density of SIMA is 3 g/cm³

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Important Points

• The only active volcano of India is situated in the Barren Island volcano of the Andaman and Nicobar Islands.
• It is composed of ash and spewing lava. A team of scientists from the National Institute of Oceanography (NIO) Goa identified this and had done an expedition on this. The volcano was erupting in small episodes lasting around 5-10 minutes.

Barren Island

The outermost surface of the Earth is called the lithosphere, or crust.

• This rigid layer contains both the oceans and landmasses.
• Most elements are found in only trace amounts within the earth’s crust, but several are abundant.
• About 98% of the total crust is made up of eight elements as oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium.
• The rest 2% is constituted by elements like titanium, hydrogen, phosphorous, manganese, sulphur, carbon, nickel, and others.
• The elements in the earth’s crust are rarely found exclusive but are usually combined with other elements to make various substances.
• Oxygen is by far the most abundant element in earth's crust at 46.6 percent, nearly half of the mass of the crust.

The correct answer is Volcanoes and Earthquakes.

Volcanoes and Earthquakes:

• The Ring of Fire is an area in the basin of the Pacific Ocean. Here a large number of earthquakes and volcanic eruptions occur.
• It covers about 40,000 km in a horseshoe shape.
• It has a continuous series of oceanic trenches, volcanic arcs, and volcanic belts, and plate movements.
• More than 75% of the world's active and dormant volcanoes are at this place.
• The Ring of Fire is a direct outcome of plate tectonics.

The Earth is divided into four main layers: the solid crust on the outside, the mantle, the outer core, and the inner core.

Important Points

The Core -

• The earthquake wave velocities helped in understanding the existence of the core of the earth.
• The core-mantle boundary is located at the depth of 2,900 km.
• The outer core is in a liquid state while the inner core is in a solid state.
• The density of material at the mantle core boundary is around 5 g/cm3 and at the centre of the earth at 6,300 km, the density value is approximately 13g/cm3.
• The core is made up of very heavy material mainly constituted by nickel and iron.
• It is sometimes referred to as the nife layer.

The correct answer is Oxygen.

Important Points

• Oxygen is the most abundant element in Earth's crust.
• The name Oxygen comes from the Greek 'oxy genes', meaning acid-forming.
• Oxygen was discovered by Joseph Priestley in Wiltshire, England, and independently by Carl Wilhelm Scheele in Uppsala, Sweden.
• Oxygen is the chemical element with the symbol O and atomic number 8.

Important Points

• A rise in temperature with an increase in depth is observed in mines and deep wells.
• These evidence along with molten lava erupted from the earth’s interior supports that the temperature increases towards the centre of the earth.
• While in the upper 100kms, the increase in temperature is at the rate of 120C per km and in the next 300kms, it is 200C per km. But going further deep, this rate reduces to a mere 100C per km.
• It is assumed that the rate of increase in the temperature beneath the surface is decreasing towards the centre.
• Temperature is always increasing from the earth’s surface towards the centre.
• The temperature at the centre is estimated to lie somewhere between 30000C and 50000C, maybe that much higher due to the chemical reactions under high-pressure conditions.