Earth's Dynamic Geology: Plates, Volcanoes, and Earthquakes

Geological Features and Processes

Lithosphere

The Lithosphere is the solid surface layer of the Earth. It has an average thickness of 100 km and is formed by the crust and the solid upper mantle, which rests upon the asthenosphere.

Convection Currents

Convection currents are movements within the Earth's mantle, driven by heat, that contribute to plate tectonics.

Volcano

Volcanoes are conical structures formed around openings in the Earth's crust by rising magma.

Earthquake

Earthquakes are sudden movements of the ground. They occur when the advance of a tectonic plate or a segment of a plate is impeded by friction with another plate or block, causing a sudden release of energy.

Fold

Folds are undulations that form in rock layers exhibiting ductile behavior when subjected to compressional geological forces during plate collisions.

Joint

Joints are fractures or cracks in rocks where there is no significant displacement of one block relative to the other.

Fault

Faults are fractures in which there is relative movement between the two blocks formed.

Earth's Internal Structure

Differences in Earth's Layers

The layers of the Earth's internal structure differ in width, thickness, and temperature.

Lithospheric Plate Boundaries

• Transform Boundary

  A Transform Boundary is the margin where a plate moves laterally alongside an adjacent plate, often in the opposite direction, without significant creation or destruction of crustal material.

• Destructive (Convergent) Boundary

  A Destructive Boundary is the margin where one plate collides with another and subducts into the mantle, where it melts.

• Constructive (Divergent) Boundary

  A Constructive Boundary is the margin where magma from the mantle rises, solidifies, and adds new material to the plate, causing it to grow.

Types of Tectonic Plates

• Oceanic Plates

  Oceanic Plates are those formed by a thin oceanic crust composed of basaltic rocks, beneath which lies the solid upper mantle layer, often referred to as the lithospheric mantle.

• Mixed Plates

  Mixed Plates are plates that have, on the lithospheric mantle, sectors formed by thin basaltic oceanic crust and thick sections formed by granitic continental crust.

Volcanic Activity

Different Types of Volcanoes

• Hawaiian Volcanoes

  Hawaiian volcanoes erupt highly fluid lava and gases; their eruptions are typically effusive and quiet.

• Strombolian Volcanoes

  Strombolian volcanoes erupt flowing lava but also release gases that produce abundant pyroclastics.

• Vulcanian Volcanoes

  Vulcanian volcanoes form viscous lava plugs that clog the crater until the pressure of the gases builds and shatters the plug, leading to explosive eruptions.

• Pelean Volcanoes

  Pelean volcanoes have lava so viscous that it forms a dome or 'spine' over the crater. The pressure of the gas builds until it shatters the dome, forming incandescent clouds (nuees ardentes).

Seismic Phenomena

Different Seismic Waves

• P-waves (Primary Waves)

  P-waves originate from the hypocenter and travel through the Earth's interior. They are compressional waves and can pass through solids, liquids, and gases.

• S-waves (Secondary Waves)

  S-waves originate from the hypocenter and travel through the Earth's interior. They are shear waves and can only pass through solid materials.

• Surface Waves

  Surface Waves originate at the epicenter and travel along the Earth's surface, often causing the most destruction.