Geomorphic Hazards – UGC NET – Geography – Solved PYQs

1. The following question consists of two statements. One is labelled as Assertion (A) and the other labelled as Reason (R). Examine the two statements carefully and select the correct answer using the codes given below. (SEPT 2013)

Assertion (A): There is a close relationship between volcanoes and plate margins.

Reason (R): About 80 percent of the world’s volcanoes are associated with the convergent plate boundaries.

Codes

(1) Both (A) and (R) are true and (R) is the correct explanation of (A)
(2) Both (A) and (R) are true and (R) is not the correct explanation of (A)
(3) (A) is true, but (R) is false
(4) (A) is false, but (R) is true

Correct Answer (1): Both (A) and (R) are true, and (R) correctly explains (A). Plate margins and volcanic zones are closely interconnected because most of the world’s volcanic eruptions occur at tectonic plate boundaries. Volcanoes can be found at either convergent or divergent plate margins, and some volcanic activity also occurs at intraplate faults. Over 80% of the world’s volcanic activity is concentrated at convergent plate margins, particularly in the Pacific Ring of Fire. Convergent plate margins are characterized by the head-on collision of plates, where the denser plate subductsand melts beneath the lighter plate. This melting process generates magma, leading to volcanic eruptions.

2. Peninsulas make up most of (SEPT 2013)

(1) Italy and Denmark
(2) Poland and France
(3) Ireland and Great Britain
(4) Austria and the Czech Republic

Correct Answer (1): Peninsulas make up most of Italy and Denmark. A peninsula is a landform bordered by water on most sides but connected to the mainland. Italy, extending into the Mediterranean Sea, and Denmark, primarily on the Jutland Peninsula in northern Europe, are prime examples. While Europe is known as a “Peninsula of Peninsulas,” with major peninsulas like the Iberian, Italian, Balkan, Scandinavian, and Jutland, it has been a significant economic, social, and cultural hub. The Italian Peninsula, stretching from the Po River region southward for about 960 km and up to 240 km wide, includes much of Italy, San Marino, and Vatican City.

3. Which of the following earthquake waves are most destructive? (DEC 2013)

(1) S-waves
(2) P-waves
(3) R-waves
(4) L-waves

Correct Answer (4): L-waves, or Love waves, are highly destructive surface waves in earthquakes. They move horizontally and have a larger amplitude than body waves (P-waves and S-waves), causing significant ground shakingand damage. Although they travel slower, their intense energy leads to greater structural destruction.

Other option

S-waves (Secondary waves): These body waves travel through the Earth, moving material perpendicular to their direction of travel. They are less destructive than L-waves because they have a smaller amplitude and do not affect the surface as Intensely. P-waves (Primary waves): The fastest body waves, P-waves travel through the Earth in a compressional manner. They are the least destructive as they have the smallest amplitude and cause less ground motion. R-waves (Rayleigh waves): Another type of surface wave, Rayleigh waves roll along the ground like waves on a lake or ocean. While they can be destructive, they are typically less so than L-waves because their energy is spread over a larger area and they cause both vertical and horizontal ground movement.

4. Given below are two statements, one labelled as Assertion (A) and the other labelled as Reason (R). Select your answer from the codes given below. (JAN 2017)

Assertion (A): Hawaiian Island is a region of volcanic activity.

Reason (R): Convergent plate margins are sites of volcanic eruptions.

Codes

(1) Both (A) and (R) are true and (R) is the correct explanation of (A)
(2) Both (A) and (R) are true but (R) is not the correct explanation of (A)
(3) (A) is true, but (R) is false
(4) (A) is false, but (R) is true

Correct Answer (2): Both A and R are true, but R is not the correct explanation of A. Hawaiian Islands were formed by a volcanic hot spot in the middle of the Pacific Plate. The Earth’s crust is made of tectonic plates that move. Volcanoes can form where plates converge or in the middle of a plate at a hotspot. The Hawaiian Islands formed as the Pacific Plate moved over a fixed hotspot. When continental and oceanic plates converge, the denser oceanic plate is subducted beneath the continental plate. This process, called subduction, forces the oceanic plate into higher temperature environments, causing partial melting and magma formation, which leads to volcanic eruptions. Convergent plates are thus sites of volcanic activity.