Which of the following statements about Ring of Fire is/are correct ? 1. It is a zone of convergence plate boundaries 2. It is an active seismic and volcanic zone 3. It is associated with deep trench Select the correct answer using the code given below :
- (a)1 and 2 only
- (b)2 and 3 only
- (c)1 only
- (d)1, 2 and 3
Correct — D, 1, 2 and 3. All three statements describe the same geological fact from three sides. The Ring of Fire was created by the subduction of tectonic plates at convergent boundaries around the rim of the Pacific, so statement 1 holds. It contains between about 750 and 915 active or dormant volcanoes — roughly two-thirds of the world's total — and about 90 per cent of the world's earthquakes occur along it, so statement 2 holds. And oceanic trenches are simply the surface expression of those subduction zones on the sea floor, which is why the belt strings together the Peru-Chile, Aleutian, Japan, Mariana, Philippine, Tonga and Kermadec trenches; statement 3 holds too. Convergence, seismicity and volcanism and a deep trench are not three separate features but one process seen at different depths.
- (a)1 and 2 only — This is the closest miss, and it is picked by candidates who file trenches under ocean-floor relief and volcanoes under tectonics, as though the two chapters were unconnected. A trench is the depression made where one plate bends down beneath another — it is a direct product of the very convergence statement 1 describes.
- (b)2 and 3 only — Dropping statement 1 removes the cause and keeps only the effects. Without convergent boundaries there would be neither the volcanic arc nor the trench, and the belt would not exist.
- (c)1 only — The name itself contradicts this. A belt called the Ring of Fire is obviously volcanic, and it is also the world's most earthquake-prone zone — the 1960 Chile, 1964 Alaska, 2004 Sumatra and 2011 Tohoku earthquakes all struck along it.
Where an oceanic plate meets another plate it bends downwards and sinks — subduction. Three things follow at once. The bend itself makes a long, narrow, very deep trench on the ocean floor. The descending slab grinds against the overriding plate, storing and releasing strain as earthquakes down to great depths. And water carried down with the slab lowers the melting point of the mantle above it, generating magma that rises to build a chain of volcanoes parallel to the trench. The horseshoe of subduction zones around the Pacific is the Ring of Fire.
The examiner's trap in this item is compartmentalisation — trenches learnt in the ocean-floor chapter, volcanoes in the vulcanicity chapter, plate margins in the tectonics chapter. Learn them as one causal chain and every statement-code question on the topic becomes a single decision instead of three. It is worth being able to name the belt's course: up the western coast of South and North America, along the Aleutians, down through Kamchatka, Japan, the Philippines and Indonesia, and out to Tonga and New Zealand. Note also that the belt is not a perfect circle — it is open along the western coast of Antarctica and the belt is conventionally described as a horseshoe. India itself sits outside the Ring of Fire; its major seismic risk comes from the Himalayan collision zone, which is a convergence of two continental plates and therefore produces mountains rather than a trench and volcanic arc.
- About 90 per cent of the world's earthquakes occur in the Ring of Fire.
- The belt holds between about 750 and 915 active or dormant volcanoes, roughly two-thirds of the world total.
- Oceanic trenches are the topographic expression of subduction zones on the ocean floor — the Mariana, Japan, Aleutian, Peru-Chile, Philippine, Tonga and Kermadec trenches all lie along it.
- The Mariana Trench, the deepest place on Earth, lies in the western Pacific and is part of this system.
- Treating trenches, volcanoes and plate margins as separate topics rather than one process.
- Assuming every convergent boundary produces a trench — a continent-to-continent collision such as the Himalayas does not.
- Placing the Mariana Trench in the eastern rather than the western Pacific.
NDA asks this either as a statement code like this one or as a location item — which trench lies in which ocean, or which country lies on the belt.
Match List I with List II and select the correct answer using the codes given below the Lists: List I (Oceanic Trench) I. Aleutian II. Kermadec III. Sunda IV. S. Sandwich List II (Location) A) Indian Ocean B) North Pacific Ocean C) South Pacific Ocean D) South Atlantic Ocean Codes:
- (a) I-B, II-D, III-A, IV-C
- (b) I-B, II-C, III-A, IV-D
- (c) I-A, II-C, III-B, IV-D
- (d) I-A, II-D, III-B, IV-C
Answer(b) I-B, II-C, III-A, IV-D
Two of its four trenches, the Aleutian and the Kermadec, lie on the Ring of Fire — which is why statement 3 of this item is true and not an unrelated ocean-floor fact.
Mariana Trench is located in the ocean floor of
- (a) Southern Atlantic Ocean
- (b) Western Pacific Ocean
- (c) Eastern Pacific Ocean
- (d) Northern Atlantic Ocean
Answer(b) Western Pacific Ocean
The single most famous trench of this belt, tested a session earlier — evidence that the association in statement 3 is exactly what NDA expects a candidate to know.
- practice — not a real PYQ
The deep oceanic trenches of the Pacific rim are formed mainly at
- (a)divergent plate boundaries
- (b)convergent plate boundaries where one plate subducts beneath another
- (c)transform fault boundaries
- (d)mid-oceanic ridges
Answer(b) convergent plate boundaries where one plate subducts beneath another — the bend of the descending slab makes the trench.
- practice — not a real PYQ
Which one of the following countries does NOT lie on the Pacific Ring of Fire?
- (a)Japan
- (b)Chile
- (c)Indonesia
- (d)Sri Lanka
Answer(d) Sri Lanka — it sits on the stable interior of the Indian plate, far from any Pacific subduction zone.