Basic Science Solutions for Class 8 Science Chapter 14 Earthquakes are provided here with simple step-by-step explanations. These solutions for Earthquakes are extremely popular among class 8 students for Science Earthquakes Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Basic Science Book of class 8 Science Chapter 14 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Basic Science Solutions. All Basic Science Solutions for class 8 Science are prepared by experts and are 100% accurate.

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The following are two causes of earthquakes:

(a) Volcanic activities
(b) Construction of dams

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The point of origin of an earthquake is called the seismic focus or hypocentre.

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The following factors determine the extent of damage due to an earthquake:

(a) Strength of the vibrations
(b) Density of population
(c) Construction of buildings

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Tsunamis are harbour waves formed by earthquakes that occur in the sea. These are huge walls of water that destroy everything that is near by, in a short time.

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The Himalayan region and the Anadaman and Nicobar Islands are two earthquake-prone regions in India.

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Buildings are protected form earthquakes in the following ways:

(a) The walls of buildings are divided into rectangular areas and diagonal pieces are inserted in them. This prevents the walls from collapsing.
(b) The bottoms of buildings are provided mobility by placing bearings between the bottom and foundation of the buildings.

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If one is indoors during an earthquake, one should take the following safety measures:

(a) The power supply should be turned off.
(b) One should crawl under a table or a couch to protect oneself.
(c) Stay away from mirrors, heavy objects, glass and other objects that may collapse and cause damage.
(d) One should not use elevators.

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Most of the earthquakes are caused by the movement of the tectonic plates. Earth consists of three layers, i.e., core, mantle and crust. The crust is a hard layer of rocks; it is not uniform and is made of huge blocks that fit together like a jigsaw. These blocks are called tectonic plates. The heat set up by the mantle causes these plates to move continuously. Sometimes, the movement causes the edges of these plates to grind against each other, or to slide under each other or to move apart from each other. These changes send a tremor through the crust, leading to an earthquake.

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The following are the effects of an earthquake:

(a) It may cause buildings to collapse, injuring and killing people.
(b) It can lead to floods and landslides that may harm humans and other organisms.
(c) It can destroy roads, railways, bridges and communication lines by creating cracks in the ground.
(d) It may cause fire and kill people.

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1. The blocks that make up the crust of the Earth are called tectonic plates.
2. The tectonic plates move continually on the mantle.
3. The weak points on the Earth's crust where earthquakes are likely to occur are called faults.
4. The instrument used to record earthquakes is called a seismograph.
5. The magnitude of an earthquake is measured on the Richter scale.
6. The point on the surface directly above the seismic focus is called the epicentre.

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(b) Pacific Ring of Fire

The Pacific Ring of Fire is the most earthquake-prone zone in the world.

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(a) modified Mercalli scale

The intensity of an earthquake is measured on the modified Mercalli scale.

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(c) 30

The energy of vibrations on the Ritcher scale increases by about 30 steps.

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(b) crawl under a table and cover one's head

During an earthquake, one should crawl under a table and cover one's head.

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(c) the collapsing of buildings

Most of the damage during an earthquake is due to buildings collapsing that destroys life and property.



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