Earth’s Interior: Heat, Volcanoes, Earthquakes, and Plate Tectonics
1. Earth’s Internal Heat
Geothermal Gradient: The Earth’s internal temperature increases with depth. The temperature rises approximately 30°C per kilometer.
Earth’s Internal Heat Source: The Earth’s internal heat originates from collisions during its formation approximately 4.5 billion years ago and from the decay of radioactive elements.
Internal Pressure and Temperature: Both temperature and pressure increase with depth within the Earth.
2. Signals of Earth’s Internal Heat
- Volcanism: Molten rock (magma) from inside the Earth’s crust erupts onto the surface.
- Earthquakes: Sudden movements or breaks in the Earth’s crust.
- Continental Drift: The slow, horizontal movement of continents.
- Isostasy: Slow, vertical movements of the Earth’s surface.
- Atmosphere: Formed approximately 4 billion years ago by gases released from the Earth’s interior.
3. Volcanism
Magma: A mixture of molten rock and gases, primarily formed within the Earth’s crust, with a tendency to be expelled onto the surface.
Lava: Molten rock that has reached the Earth’s surface, having lost most of its gases.
Volcanic Products:
- Gaseous State: Primarily carbon dioxide and water vapor.
- Liquid State: Lava with higher temperature and lower viscosity flows more readily.
- Solid State: Tephra, which includes volcanic rock fragments ejected during eruptions.
4. Types of Volcanic Activity
Four main types of volcanic activity exist: Hawaiian, Strombolian, and Vulcanian.
5. Earthquakes
Earthquakes (Seismoa): Vibrations generated by movement or breaks in the Earth’s crust.
Hypocenter: The point or location within the Earth’s crust where the break or movement originates.
Epicenter: The point on the Earth’s surface directly above the hypocenter.
6. Seismic Waves and Earth Structure
The Earth’s structure is composed of layers or plates:
- Oceanic Lithospheric Plate: Primarily composed of basalt.
- Continental Lithospheric Plate: Primarily composed of granite.
- Mixed Lithospheric Plate: Composed of both oceanic and continental crust.
7. Plate Movements
- Divergent Plate Boundaries: Plates move away from each other, allowing molten mantle material to rise and create new crust, often resulting in volcanism.
- Convergent Plate Boundaries: Plates collide, with the denser plate subducting beneath the less dense plate, leading to mountain formation.
- Transform Plate Boundaries: Plates slide past each other horizontally, generating seismic activity.
8. Volcanoes, Earthquakes, and Plate Tectonics
- Plate Tectonics: Explains the movement of lithospheric plates and their consequences.
- Seismicity: Earthquakes are generated in areas where plates collide.
- Volcanism: Occurs at rift zones, subduction zones, or hot spots.
9. Formation of Mountains
Mountain ranges form when two continental plates collide, causing the crust to thicken.
Earth’s Continents and Oceans: Features include mountains, high plains, and continental shelves.
Depths of the Oceans: Features include ocean mountains, ocean trenches, abyssal plains, and submarine volcanoes.
Magmatic Rocks: Rocks formed from the cooling and solidification of magma.
Plutonic Rocks: Rocks that crystallize within the Earth’s crust.
Metamorphic Rocks: Rocks that have been transformed by high temperature and pressure within the Earth.
Lava Flow (Kolada Lava): Hardened lava on the walls of a volcano.
Rift: A split or fracture between two tectonic plates.
Convection Current: The process where gas heats up, rises, cools down, and then descends.