Question

Question 7 1 pts What type of deformation commonly occurs at shallow levels in the crust? ductile deformation brittle deformation recrystallization of minerals metamorphism Question 8 1 pts Which of the following statements regarding shallow and deep earthquakes is true? deep and shallow earthquakes almost only occur near subduction zones the deeper earthquakes will be closer to the trench than shallower ones the depth pattern of earthquakes can be used to determine which way the subducting plate is inclined this area has the potential for large magnitude earthquakes

Answer 1

Ans. 7. Of the following statements, the deformation that takes place at shallow levels in the crust is (b) brittle deformation.

When a rock undergoes pressure changes (increase in pressure) which is not so high along with low temperature surge, the strength of the rock also decreases. This makes the rock to undergo fracture and form faults quite easily, hence it is brittle in nature. Moreover, the confining pressure and overburden pressure is also less at shallow depths. On the contrary, when the rocks are formed at higher depths with high temperature and pressure, it tends to form which are ductile in nature.

Ans. 8. The correct answer is (c) the depth pattern of earthquakes can be used to determine which way the subducting plane is inclined. This is because earthquakes take place during tectonic plate movements, ans also during convergence or divergence. If a convergence occurs, then one plate will definitely undergo subduction, hence the inclination plane and depth can easily be determined.