Q1.
Observe the map showing the distribution of earthquakes and volcanoes (Fig. 2.4). Can you identify which continents and countries are located around the Ring of Fire with the help of an atlas or a globe?
Answer
Method first: in Fig. 2.4 trace the horseshoe-shaped band of dense red dots and black triangles that rings the Pacific Ocean. Then lay that band over the political map in your atlas and list what it crosses, going round the ring.
Continents touched by the Ring of Fire — four: Asia, North America, South America and Australia/Oceania. (Antarctica is grazed at its Pacific edge; Europe and Africa lie outside the ring altogether.)
Countries, going round the ring:
| Side of the Pacific | Countries on the ring |
|---|---|
| Western Pacific (Asia) | Indonesia, Philippines, Malaysia (east), Papua New Guinea, Japan, Taiwan, China (east coast), Republic of Korea, Russia (Kamchatka and the Kuril Islands) |
| South-western Pacific | Solomon Islands, Vanuatu, Fiji, Tonga, New Zealand |
| Northern Pacific | United States (Alaska and the Aleutian Islands) |
| Eastern Pacific (North and Central America) | Canada (west coast), United States (Washington, Oregon, California), Mexico, Guatemala, El Salvador, Nicaragua, Costa Rica, Panama |
| Eastern Pacific (South America) | Colombia, Ecuador, Peru, Bolivia, Chile, Argentina (Andean edge) |
Why the ring is a ring: look back at Fig. 2.3. The Pacific plate is a single huge oceanic plate, and almost its entire edge is a boundary with some other plate — Eurasian, Indo-Australian, North American, South American, Antarctic. Because oceanic crust is thin and heavy (5 km against 30 km for continental crust, Fig. 2.1), it sinks beneath the lighter continental plates all round. Sinking plates make both violent earthquakes and the magma for volcanoes. So the shape of the ring is simply the shape of one plate's boundary.
Check it yourself: India does not lie on the Ring of Fire — it sits on the Indo-Australian plate, well inside it. India's earthquake belt comes from a different boundary: the collision with the Eurasian plate along the Himalaya.