🔹 What is a Volcano?
A volcano is an opening in the Earth’s crust through which magma, gases, and ash are expelled.
🔹 Structure of a Volcano
- Magma Chamber – Storage of molten rock
- Vent – Opening through which magma escapes
- Crater – Bowl-shaped depression
- Lava – Magma that reaches the surface
🔹 Types of Volcanoes
1. Based on Activity
- Active Volcano
- Erupts frequently
- Example: Mount Etna
- Dormant Volcano
- Sleeping but can erupt
- Example: Mount Fuji
- Extinct Volcano
- No eruption in historical times
2. Based on Shape
- Shield Volcano
- Broad and gentle slopes
- Example: Mauna Loa
- Composite (Stratovolcano)
- Steep slopes
- Alternating lava and ash layers
- Cinder Cone Volcano
- Small and steep
🔹 Causes of Volcanic Eruptions
- Movement of tectonic plates
- Pressure of gases in magma
- High temperature inside Earth
🔹 Types of Volcanic Eruptions
- Effusive Eruption – Lava flows slowly
- Explosive Eruption – Violent, releases ash and gases
🔹 Distribution of Volcanoes
- Mostly found along plate boundaries
- Major zone: Pacific Ring of Fire
🔹 Effects of Volcanoes
🌟 Positive Effects
- Formation of fertile soil
- Creation of new land
- Mineral resources
- Geothermal energy
⚠️ Negative Effects
- Loss of life and property
- Air pollution
- Climate change (ash clouds)
- Lava destruction
🔹 Volcano Disaster Management
- Monitoring volcanic activity
- Evacuation plans
- Hazard mapping
- Public awareness
🔁 Difference Between Earthquake & Volcano
| Feature | Earthquake | Volcano |
|---|---|---|
| Nature | Sudden shaking | Eruption of magma |
| Cause | Plate movement | Magma pressure |
| Warning | Very little | Sometimes predictable |
| Impact | Short duration | Can last longer |