Which one of the following statements regarding S-waves is not correct ?
- A.S-waves are slower than P-waves.
- B.During an earthquake S-waves are less destructive to structures like buildings and highway overpasses.
- C.S-waves can travel only through solids and cannot travel through the Earth's outer core.
- D.Seismologists have concluded that the Earth's outer core must be liquid or fluid
Correct answer
Explanation
The correct answer is B. S-waves are not less destructive; their side-to-side shaking does more damage to buildings and overpasses than P-waves do. S-waves, or secondary waves, are transverse body waves: they move the ground at right angles to the direction in which they travel. P-waves, or primary waves, are push-and-pull waves that travel fastest and reach a seismograph first, and they do comparatively little damage. S-waves arrive next with larger amplitude and strong shearing motion, so structures suffer more from them. Surface waves arrive last and are the most destructive of all. Option A is correct because S-waves travel at roughly 60 percent of the speed of P-waves. Option C is correct because a liquid cannot resist shearing, so S-waves cannot pass through the outer core and leave a shadow zone beyond about 103 degrees from the epicentre. Option D is correct because that very shadow zone led seismologists to conclude that the outer core is liquid. Exam tip: arrival order P, then S, then surface waves; damage order is the reverse, and S-waves never cross liquid.
Practice Questions
View allAn avalanche is a type of which one of the following disasters ?
- A.Atmospheric
- B.Terrestrial
- C.Aquatic
- D.Biological
Show answer
An avalanche is a sudden slide of snow, ice and debris down a mountain slope, a movement of material on the land surface, so it is grouped with terrestrial disasters.
Read the full explanation →Which of the following statements is/are correct? 1. Angular velocity for all locations on the Earth's surface is the same while linear velocity varies. 2. Linear velocity is maximum at the equator and minimum at the poles. Select the correct answer using the code given below.
- A.1 only
- B.2 only
- C.Both 1 and 2
- D.Neither 1 nor 2
Show answer
Every point on the Earth turns through 360 degrees in the same time, but points nearer the equator travel a longer circle and so move faster.
Read the full explanation →Consider the following tributaries of river Ganga : 1. Gandak 2. Kosi 3. Ghaghara 4. Gomti Which one of the following is the correct order of the above rivers from east to west?
- A.3-4-1-2
- B.2-1-3-4
- C.2-3-1-4
- D.1-2-4-3
Show answer
Going from east to west, the order is Kosi, Gandak, Ghaghara and Gomti. All four join the Ganga from the north.
Read the full explanation →The extent of damage caused by earthquake is not influenced by which one of the following ?
- A.Strength of earthquake
- B.Population density
- C.Type of building
- D.Climate of the area
Show answer
The damage an earthquake does depends on how strongly the ground shakes and on what, and who, stands on it, not on the region's climate.
Read the full explanation →What is culturable wasteland?
- A.Land that has been left fallow in last four years
- B.Land that has been left fallow between one and two years
- C.Land that has been left fallow for less than one year
- D.Land that has been left fallow for more than five years
Show answer
In India's land-use records, land that can be farmed but has lain uncultivated for over five years is called culturable wasteland.
Read the full explanation →