Understanding Earthquakes: Origins, Measurement, and Risk
Understanding Earthquakes
Earthquake Origins
As an earthquake originates:
- Stress builds up.
- Tension increases, and materials deform.
- Materials fracture, releasing energy that vibrates the ground.
Measuring Earthquakes
Seismometers detect even very weak earthquakes that go unnoticed by people, drawing graphic seismograms. The magnitude of an earthquake is the amount of energy released, measured on the Richter scale, which is open-ended and has no limit.
Intensity vs. Magnitude
Intensity and magnitude are
Read MoreGeological Processes and Landforms: Definitions & Examples
Geological Processes and Landforms
Seismogram: A chart created by a seismograph (a device that detects earthquakes and deformations). These graphs allow us to locate the epicenter of the earthquake, its magnitude, and the depth of focus.
Subsidence: The slow and gradual sinking of the ground, often due to soil settlement after the extraction of fluids (water and oil), or by seismic liquefaction phenomena.
Collapses: Sharp vertical drops, such as the collapse of a cave resulting from the dissolution
Read MoreUnderstanding Earth’s Hydrosphere: Oceans, Rivers, and Glaciers
The Hydrosphere: Earth’s Waters
The hydrosphere encompasses all of Earth’s water.
Approximately 70% of the Earth’s surface is covered by seawater, primarily in oceans and seas.
The remaining water is found in inland rivers, lakes, groundwater, and glaciers.
Marine Waters
Marine waters differ from inland waters due to their salinity. The average salinity of the oceans is 35%. Oceans are large bodies of saltwater.
Major Oceans
- Pacific Ocean: The oldest and largest ocean, characterized by its great depth
Soil Composition, Types, and Land Pollution Issues
Understanding Soil Composition and Structure
Soil is the loose material on the Earth’s surface situated above solid rock.
Soil Layers (Horizons)
Soil is typically composed of three main layers or horizons:
- Topsoil (A horizon): The uppermost layer, which gains organic material from the decomposition of plants and animals.
- Subsoil (B horizon): Located beneath the topsoil, this layer accumulates materials leached from the horizons above.
- Weathered Bedrock (C horizon): This layer contains loose pieces of
Understanding Orogeny: Formation of Mountain Ranges
Orogeny: The Birth of Mountains
Orogeny: The set of geological processes that give rise to large mountain ranges or orogens. They form on the borders of converging tectonic plates and, depending on the type of convergence, may be of the Andean and island arc collision type.
The Tectonic Orogeny Before Plate Theory: Fixism
Early orogenic theories did not consider the mobility of the masses. According to the fixist hypothesis, the distribution of continents and oceans has always been the same. The main
Read MoreUnderstanding Earth’s Relief, Rock Formation, and Textures
Earth’s Relief and Landforms
The Earth’s surface exhibits diverse relief features.
Types of Relief
Relief areas can be emergent (above sea level) or submerged. Major relief features include:
- Mountain Ranges: Formed by the convergence of tectonic plates.
- Plains: Flat or gently undulating areas. Plateaus are elevated plains.
- Depressions: Areas lower than the surrounding terrain.
Rock Formation and the Rock Cycle
The Earth’s surface is composed of various rock types, including sedimentary rocks.