1. Compare normal, reverse, and strike-slip faults 2. Describe the elastic rebou
ID: 290194 • Letter: 1
Question
1. Compare normal, reverse, and strike-slip faults
2. Describe the elastic rebound theory.
3. Describe the motions of the four types of seismic waves. Which are body waves, and which are surface waves?
4. Explain the differences among the scales used to describe the “size” of an earthquake.
5. How does seismicity on mid-ocean ridges compare with the seismicity at convergent or transform boundaries? Do all earthquakes occur at plate boundaries?
6. What is a Wadati-Benioff zone, and why was it important in understanding plate tectonics?
7. What is a tsunami, and why does it form?
8. Explain how liquefaction occurs in an earthquake and how it can cause damage.
9. What types of structure are most prone to collapse in an earthquake? What types are most resistant to collapse? What causes most loss of life during an earthquake?
Explanation / Answer
1) - Due to frequent activity of tectonic plates, different types of faults are generated like:-
a- Normal fault- which forms when the hanging wall slides down in relation to the foot wall. This results from the gravitational pull of fault plane which is why they are normal. Mostly found at divergent boundaries.East Africa rift is an example of this.
b- Reverse fault- which is the opposite of normal fault , where the foot wall moves down and hanging wall moves up. They are common at convergent boudaries. Himalaya mountain is an example of reverse fault.
c- Strike-slip fault -they form walls that move sideways unlike normal and reverse fault moving up and down. The San Andreas fault is an example of strike -slip fault.
2)- The elastic rebound theory was put froth by a geophysicist Harry Fielding Reid after the 1905 ,San Fransico earthquake. This theory suggest that earth builds up stress which is caused by the movement of tectonic plates. At certain point this stress becomes so great that earth rupture to release some stress causing an earthquake.
3)- Seismic waves are the waves of energy released during the sudden rupture of rocks within the earth .This energy wave travels through the earth and is recorded on seismographs. There are generally 4 types of seismic waves which are as follows:-
A- Primary wave , which is the fastest kind of seismic wave and eventually the first to arrive in the seismic station. They move through solid rocks and faults and also through liquid layers of the earth. Because of the pull and push nature of Pwave are also called as compressional waves.
B- Secondary wave or S wave, which is slower than the P wave and can only travel through the solid rocks. This wave moves rock particles up and down or side to side perpendicular to the direction the wave is travelling in.
C- Love wave , which is confined to the surface of the crust whichmoves the ground side to side or horizontally.
D- Rayleigh wave which moves the ground up and down and side to side in the same direction where the wave is travelling because it rolls like a wave rolls across an ocean. It is a surface wave, most of the shock felt by this kind of wave, which can be larger than the other waves.
Primary wave and Secondary waves are body waves . while the love wave and the Rayleigh wave are the surface waves.
4)- A-Mercalli intensity scale , it measures the intensity of an earthquake by the amount of damage it causes.
B- Richter scale, it allows to determine the magnitude using the amplitude of the largest deflection on the seismograph an d the distance of the epicenter.
C- Moment- magnitude scale , which measures the magnitude moment by the amplitude of several different waves. the area of a fault slip and the amount of slip that occured.
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