Ch-3: Interior of the Earth

Earth ka radius lagbhag 6,378 km hai. Iske interior ko samajhna zaroori hai taaki hum landscape development, earthquakes aur tsunami generation ko samajh sakein.

1. Sources of Information

Direct Sources:

• Mining: Gold mines (South Africa) 3-4 km gahri hain.
• Drilling: Kola (Arctic Ocean) mein 12 km tak drilling hui hai.
• Example: Volcanic eruption se nikalne wala magma laboratory analysis ke liye direct material provide karta hai.

Indirect Sources:

• Depth badhne par Temperature, Pressure aur Density bhi badhti hai.
• Meteors: Inka material aur structure earth ke jaisa hi hota hai.
• Gravitation: Poles par gravity zyada aur equator par kam hoti hai; is farq ko Gravity Anomaly kehte hain.
• Seismic Activity: Earthquake waves interior ka sabse important source hain.

2. Earthquakes & Waves

Earthquake energy release hone se paida hota hai jo har disha mein travel karti hai.

• Focus/Hypocentre: Jahan se energy release hoti hai.
• Epicentre: Surface par Focus ke thik upar wala point.

Wave Types:

1. Body Waves: Interior se travel karti hain.
   • P-waves: Primary waves, fast, sound waves jaisi, aur ye Gas, Liquid, Solid teeno se guzarti hain.
   • S-waves: Secondary waves, sirf Solid se travel karti hain.
2. Surface Waves: Sabse damaging aur destructive waves.

3. Structure of the Earth

• Crust: Outermost brittle part. Oceanic (5 km) aur Continental (30-70 km) thickness.
• Mantle: 2,900 km tak faila hai. Upper mantle ko Asthenosphere (weak zone) kehte hain, jo magma ka main source hai.
• Core: Outer core liquid hai, inner core solid. Heavy metals Nife (Nickel + Iron) se bana hai.

4. Volcanic Landforms

• Example: Shield Volcanoes (Hawaii) basalt lava se bante hain aur steep nahi hote.
• Example: Flood Basalt (Deccan Traps, India) bahut bada lava area cover karta hai.

Intrusive Forms (Underground structures):

Batholiths (large domes), Lacoliths (dome with pipe), Sills (horizontal), aur Dykes (vertical wall-like).

--- EXERCISE SOLUTIONS ---

1. MCQs:

• (i) Most destructive waves? → (c) Surface waves
• (ii) Direct source? → (b) Volcanoes
• (iii) Deccan Trap eruption? → (b) Flood
• (iv) Lithosphere? → (b) Crust and upper mantle

2. Short Answers (30 Words):

• (i) Body waves: Ye waves energy release hone par focus se nikalti hain aur earth ki body ke andar se har disha mein travel karti hain.
• (ii) Direct sources: Surface rocks, mining (Gold mines), drilling projects (Kola project), aur volcanic eruptions.
• (iii) Shadow zone: Specific areas jahan seismic waves (P ya S) record nahi hoti hain, refraction ya material state ki wajah se.

3. Long Answers (150 Words):

• (ii) Intrusive forms: Jab magma surface tak nahi pahunchta aur crust ke andar hi thanda ho jata hai, use 'intrusive form' kehte hain. Isme Batholiths, Lacoliths, Sills aur Dykes jaise shapes bante hain.

Activity / Project: Tsunami waves kaise generate hoti hain? Tsunami waves tab paida hoti hain jab Earthquake ka Epicentre ocean floor ke niche ho aur uska magnitude kafi zyada ho. Iska model banayein!

[Internal Layers]

🌍

Crust (Brittle)
Mantle (Astheno)
Outer Core (Liquid)
Inner Core (Solid)

[Wave Shadow Zone]

P-waves: 105°-145° 🚫
S-waves: > 105° 🚫
(S-wave zone is larger)

[Measurement]

Magnitude: Richter (0-10)
Intensity: Mercalli (1-12)

🌋 🔥 ⚡

"Dynamics of the Interior"