Earth Structure and Plate Tectonics Fundamentals

Direct and Indirect Geological Methods

Direct Geological Methods

These methods are based on obtaining accessible material directly from the Earth. They include:

• Outcrops of rocks
• Study of magma
• Boreholes or soundings

Indirect Geological Methods

These methods study how the Earth behaves internally in relation to physical, chemical, or mathematical properties:

• Geothermal: The amount of heat flow that reaches the Earth's surface from the interior.
• Gravity: Variations in gravitational pull.
• Magnetics: Variations in the magnetic field.
• Electric resistivity of rocks.
• Seismic propagation: The movement of seismic waves during earthquakes.

Earthquake Fundamentals

An earthquake occurs when a particular movement originates within the Earth's layers.

• Hypocenter: The specific point where a crustal earthquake movement originates.
• Epicenter: The point on the Earth's surface directly above where the earthquake originates.

Models of the Earth's Structure

Chemical Models of the Earth

• Crust (Bark): The outermost layer of the Earth, which can be continental or oceanic.
• Mantle (Manto): Located under the crust, divided into interior and exterior sections.
• Core: The innermost layer, consisting of inside and outside parts.

Physical Models of the Earth

• Lithosphere: The superficial and outermost layer.
• Asthenosphere
• Mesosphere
• Endosphere (Endosfera)

Theory of Plate Tectonics

According to this theory, the lithosphere is divided into plates that move over the asthenosphere because the materials there are fluid.

Tectonics and Tectogenesis

Tectonics: The study of how forces are generated that deform and dislocate the lithosphere.

Tectogenesis: The set of processes by which rocks are deformed due to pressure, temperature, and the forces of compression and relaxation.

• Diaclases: Fractures or broken strata without significant displacement.
• Faults: Fractures in brittle layers. While some definitions vary, they are generally categorized as:

1. Normal faults
2. Reverse faults
3. Transform faults

• Folds: The bending of layers exhibiting plastic behavior.

Seismology: Measurement and Tools

Seismograph: An apparatus used to detect earthquakes or seismic activity.

Seismogram: The visual drawing or record that appears on a seismograph.

Intensity: The effect of an earthquake on buildings, structures, and the perceptions of people. It is measured using the Mercalli scale, which consists of 12 values.

Magnitude: The seismic energy released by an earthquake, measured by the Richter scale.

Volcanoes and Volcanic Activity

Parts of a volcano: Magma chamber, vent (fireplace), crater, and volcanic cone.

Interplate and Intraplate Volcanism

Interplate: Volcanism occurring at the limits generated by lithospheric plates.

Intraplate: Volcanism generated inside the plates, often associated with hotspots.