Essential Geological Terms and Natural Hazards

Fundamental Earth Systems

Biodiversity: The richness and variety of species within an ecosystem and the relative abundance of each species. It is categorized into three aspects: species variety, ecosystem diversity, and genetic diversity.

Geosphere: The rocky structure of the Earth system that supports all other terrestrial systems. Located in the uppermost part of the planet, it serves as the primary source of mineral and energy resources.

Natural Geological Hazards

Geological Hazard: Any condition or natural geological process, whether natural or human-induced, that generates economic or social harm to human communities. The prediction, prevention, and correction of these hazards must employ specific geological criteria.

Seismic and Volcanic Activity

• Volcano: The most direct manifestation of geothermal energy, consisting of fractures through which magma is expelled. It represents a significant natural geological risk.
• Earthquake: A vibration of the Earth produced by the abrupt (paroxysmal) release of elastic energy stored in rocks when they break after being subjected to high strain.
• Seismic Waves: Vibrational waves that transmit the force generated at the earthquake focus to the epicenter in proportion to the intensity and magnitude of the event.
• Fault: A discontinuity formed by fractures in the Earth's surface when tectonic forces overcome the resistance of the rocks.
• Fault Plane: The surface along which rock blocks move apart during a faulting event.
• Lava Flow: A mass of lava that moves down the slope of a volcano until it solidifies.
• Pyroclastic Material: Any solid piece of volcanic material ejected into the air during an eruption.

Water-Related Geological Phenomena

• Tsunamis: Giant waves caused by undersea earthquakes.
• Seiche: A wave induced in inland waters, such as lakes or reservoirs.
• Liquefaction: An effect produced on land consisting of unconsolidated sediments which, as a result of ground vibration, behave like a fluid.

Mass Wasting and Slope Processes

Slope: The inclined surface or slope of a hill.

• Creep: A slow and discontinuous gravitational descent of altered superficial materials. It results from alternating expansion and retraction, causing a steady downhill sliding movement.
• Mud Flow: A continuous and rapid flow of plastic and viscous materials saturated with water. It occurs without a specific failure plane and moves with greater speed at the surface.
• Solifluction: A process similar to mud flow but occurring more slowly, resulting from the combination of creep and flow.
• Slides: Downhill movements of rock on a failure surface. These can be translational (where the fracture surface is parallel to the slope, separating competent rock from incompetent rock) or rotational/slump (slippage along a curved failure surface, often in uniform cohesive soils).
• Detachment: The sharp, isolated fall of rock blocks or fragments from a slope.
• Avalanche: Landslides involving a dry mass of sand or stone blocks.
• Subsidence: The slow and gradual sinking of land, which may be natural or induced by human activities.
• Collapse: An abrupt vertical collapse of land, either natural or induced by human activities.