Interior of the Earth

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Questions and Answers

What is the name of the outermost solid part of the Earth?

Crust

Which earthquake waves vibrate parallel to the direction of the wave?

S-waves

Surface Waves

Tectonic Waves

P-waves (correct)

The mantle extends from Moho's discontinuity to a depth of 2,900 km. True or False?

True

Volcanoes that are the largest of all the volcanoes on Earth are called ______________.

Shield Volcanoes Signup and view all the answers

What do you imagine about the nature of the earth?

a solid ball like a cricket ball or a hollow ball with a thick cover of rocks Signup and view all the answers

What is the most easily available solid earth material?

surface rock or the rocks we get from mining areas Signup and view all the answers

What is the purpose of the Deep Ocean Drilling Project and Integrated Ocean Drilling Project?

to explore the conditions in the crustal portions Signup and view all the answers

What is the source of direct information about the earth's interior?

volcanic eruption Signup and view all the answers

The temperature and pressure increase with the increasing distance from the surface towards the interior in deeper depths.

True Signup and view all the answers

What is the reason for the earth shaking?

release of energy, which generates waves that travel in all directions Signup and view all the answers

What is the term for the point where the energy is released?

hypocentre Signup and view all the answers

What is the term for the point on the surface nearest to the focus?

epicentre Signup and view all the answers

What is the reason for the difference in gravity values at different latitudes on the surface?

the distance from the centre at the equator being greater than that at the poles Signup and view all the answers

What is the term for the difference between the expected and observed gravity values?

gravity anomaly Signup and view all the answers

What type of wave is generated due to the release of energy at the focus?

body waves Signup and view all the answers

What is the term for the waves that move along the surface?

surface waves Signup and view all the answers

What is the term for the zone where earthquake waves are not reported?

shadow zone Signup and view all the answers

Which one of the following earthquake waves is more destructive?

Surface waves Signup and view all the answers

Which one of the following is a direct source of information about the interior of the earth?

Volcanoes Signup and view all the answers

Which type of volcanic eruptions have caused Deccan Trap formations?

Flood Signup and view all the answers

Which one of the following describes the lithosphere?

Crust and upper mantle Signup and view all the answers

What are body waves?

Body waves are seismic waves that travel through the interior of the Earth. Signup and view all the answers

Name the direct sources of information about the interior of the earth.

Direct sources of information about the interior of the Earth include volcanoes. Signup and view all the answers

Why do earthquake waves develop a shadow zone?

Earthquake waves develop a shadow zone due to refraction within the Earth's interior. Signup and view all the answers

Briefly explain the indirect sources of information of the interior of the Earth other than those of seismic activity.

Indirect sources of information about the Earth's interior include analyzing rocks brought up by volcanic eruptions and studying Earth's magnetic field. Signup and view all the answers

What are the effects of the propagation of earthquake waves on the rock mass through which they travel?

Earthquake waves can cause shaking, fracturing, and displacement of rock layers. Signup and view all the answers

What do you understand by intrusive forms? Briefly describe various intrusive forms.

Intrusive forms refer to igneous rock formations that cool below the Earth's surface. Examples include batholiths, lacoliths, sills, and dykes. Signup and view all the answers

Study Notes

Structure of the Earth's Interior

The Earth's interior is divided into several layers, including the crust, mantle, outer core, and inner core.
The crust is the outermost solid layer, ranging in thickness from 5 km to 70 km.
The mantle is the layer beneath the crust, extending from the Moho's discontinuity to a depth of 2,900 km.
The outer core is a liquid layer, while the inner core is a solid layer made up of heavy materials like nickel and iron.

Earthquake Waves

Earthquake waves are generated by the release of energy at the focus of an earthquake.
There are two types of earthquake waves: body waves and surface waves.
Body waves are generated due to the release of energy at the focus and move in all directions through the body of the Earth.
Surface waves are generated by the interaction of body waves with the surface rocks and move along the surface.
P-waves are a type of body wave that moves faster and are the first to arrive at the surface.
S-waves are another type of body wave that can only travel through solid materials and arrive at the surface with some time lag.

Shadow Zone

The shadow zone is an area where earthquake waves are not reported.
The shadow zone is different for each earthquake.
The study of different events reveals that for each earthquake, there exists an altogether different shadow zone.
The shadow zone of P-waves appears as a band around the Earth between 105° and 145° away from the epicentre.
The shadow zone of S-waves is much larger than that of P-waves.

Types of Earthquakes

Tectonic earthquakes are the most common type, generated due to the sliding of rocks along a fault plane.
Volcanic earthquakes are a special class of tectonic earthquakes, confined to areas of active volcanoes.
Reservoir-induced earthquakes occur in areas of large reservoirs.
Collapse earthquakes occur when the roofs of underground mines collapse.
Explosion earthquakes are caused by the explosion of chemical or nuclear devices.

Effects of Earthquakes

Ground shaking is a major effect of earthquakes.
Other effects include differential ground settlement, land and mud slides, soil liquefaction, and structural collapse.
Tsunamis can occur if the epicentre of the earthquake is below oceanic waters and the magnitude is sufficiently high.

Measuring Earthquakes

Earthquake events are scaled according to magnitude or intensity.
The magnitude scale is known as the Richter scale, which measures the energy released during the quake.
The intensity scale is named after Mercalli, which takes into account the visible damage caused by the event.

Volcanoes

Volcanoes are classified based on the nature of eruption and the form developed at the surface.
Shield volcanoes are the largest type of volcanoes on Earth, characterized by low-explosivity and gentle slopes.
Cinder cone volcanoes are formed by the accumulation of ash and cinder from small-scale eruptions.### Volcanic Landforms
Trap formations cover a larger area than present-day formations and develop into cinder cones
Mid-Ocean Ridge Volcanoes occur in oceanic areas, with a system of mid-ocean ridges over 70,000 km long that experiences frequent eruptions

Composite Volcanoes

Characterized by eruptions of cooler and more viscous lavas than basalt
Often result in explosive eruptions, with large quantities of pyroclastic material and ashes accumulated in the vicinity of vent openings
Formations resemble composite volcanoes, with lava and pyroclastic material building up around the vent

Volcanic Rocks

Formed from lava that cools and solidifies, either on the surface or in the crust
Classified as volcanic rocks (cooling at the surface) and plutonic rocks (cooling in the crust)

Intrusive Forms

Formed when lava cools within the crustal portions, assuming different shapes
Examples include batholiths, lacoliths, phacoliths, sills, and dykes

Batholiths

Large bodies of magmatic material that cool in the deeper depths of the crust, developing into large domes
Appear on the surface only after denudational processes remove overlying materials
Cover large areas and can assume depths of several km, with granitic bodies

Lacoliths

Large dome-shaped intrusive bodies with a level base and connected by a pipe-like conduit from below
Resemble surface volcanic domes of composite volcanoes, with a localized source of lava

Phacoliths and Sills

Near-horizontal bodies of intrusive rocks found at the base of synclines or top of anticlines in folded igneous country
Called phacoliths, with a definite conduit to the source beneath in the form of magma chambers
Thinner ones are called sheets, while thick horizontal deposits are called sills

Dykes

Formed when lava makes its way through cracks and fissures in the land, solidifying almost perpendicular to the ground
Develop a wall-like structure, with examples found in the western Maharashtra area
Considered the feeders for eruptions that led to the development of the Deccan traps

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Description

This quiz is about the nature of the earth's interior, exploring what we know about it and how we gather information. Test your understanding of the earth's structure and composition.