Sustainable Development and Earth’s Dynamic Processes

Posted on Dec 15, 2024 in Geology

Management

  • Reduction: Do not produce such waste.
  • Reuse: If something can be used, use it for the same purpose.
  • Recycling: Transforming waste.

Processing

  • Waste for energy.

Composting

  • Microorganisms form a compound, compost, an inorganic fertilizer used to improve soil properties.



Resources and Sustainable Development

  • Resources: Material goods and services provided by nature undisturbed by human beings.
  • Impacts: The alteration or effect that a particular human action produces on the environment in its various aspects.
  • Risks: Possibilities of occurrence or catastrophic damage to the environment due to natural phenomena or human action.

Natural Resources

Everything that humanity derives from nature to meet their needs:

  • Non-renewable: Limited quantities (oil).
  • Renewable: Not exhausted (solar energy).
  • Potentially renewable: Although consumed, they are regenerated by nature, but if used excessively, they can be exhausted (forests).

Sustainable Development

Development that satisfies the needs of the present generation without compromising the ability of future generations to meet their own needs.

  • Carrying capacity: An ecosystem’s capacity to sustain the life it holds.
  • Ecological Footprint: Land resources required to produce what humans need and to assimilate the waste generated.

Sustainable Development Principles

  • Principle of Harvest: Extraction rates must be equal to or less than regeneration rates.
  • Principle of Sustainable Emptying: Extraction rate equals the rate of creation of renewable substitute resources.
  • Principle of Sustainable Emission: Equal to or less than the assimilative capacities of ecosystems that receive such waste.
  • Principle of Zero Emission: Zero emission of toxic and bioaccumulative pollutants.
  • Principle of Sustainable Integration: Human settlements must not exceed the carrying capacity of a territory.
  • Principle of Selection of Sustainable Technologies: Encouraging more efficient technologies.
  • Principle of Caution: Development models used should not exceed the limits of ecosystems and should avoid catastrophes and disasters.

Use of Water

If the water used cannot be reused, it is consumptive use, as in agriculture (70%), industry (22%), and urban areas (8%).

Overexploitation

A person needs 1.5 liters; Spain uses 350 liters per person per day. Water is obtained from rivers, streams, lakes, and groundwater. It is retained while using an amount equal to or less than the rate of water renewal. Groundwater is extracted at a faster rate than it recharges.

Brackish Water

Saline Intrusion: In coastal areas, when water is pumped from wells along the coast, seawater moves inland, replacing freshwater with saltwater (unusable).

Lawsuits Biosphere: Biodiversity

The variability of organisms and ecosystems of a given area or the whole Earth.

Soil

A thin layer on the ground, consisting of a mixture of minerals, organic matter, living things, air, and water, that supports the growth of plants.

Agricultural and Livestock Resources, Domestication

Agriculture depends on resources (soil, water, and biodiversity). Since 1950, intensive agriculture has been used. Only 11% of the Earth’s surface does not have cultivation problems. To increase land, artificial irrigation, deforestation, fertilizers, and genetic engineering are used.

Organic Farming

A system of exploitation based on the utilization of natural resources without using chemicals or genetically modified organisms for organic food, while retaining the fertility of soil and respecting the environment. Drip irrigation, renewable energy, natural biodiversity, biological pest control, crop rotation, etc.

Conventional Energy

  • Renewable fuels: Coal, oil, natural gas, high calorific power… highly polluting because they produce carbon dioxide (CO2), responsible for the increase in the greenhouse effect. Many products are obtained from distillation (plastics, cosmetics).
  • Nuclear Fission Energy: Occurs when the nucleus of an atom is broken, causing lighter elements and releasing large amounts of energy. The fuel is uranium, a high-risk element due to radioactivity.
  • Hydropower: Uses the energy of water in its fall, drives a turbine, and generates electricity. It does not produce pollutants; the drawbacks are that the construction of dams alters ecosystems, the river flow regime is modified, and migratory fish encounter a barrier.

Alternative Energy

  • Solar power: Can be turned into heat using solar cells that heat water or electricity through photovoltaic panels.
  • Wind power: Uses the wind to produce electricity. Wind turbines are used (grouped in wind farms). The drawback is that the blades cause visual impact and are a danger to birds.
  • Biomass energy: Provided by wood, wood waste, … steam is obtained to generate electricity or biofuels.
  • Geothermal energy: Water is obtained by capturing steam or hot water from the subsoil of the Earth’s crust to produce heat or electricity.
  • Tidal energy: Uses the force of the tides to produce electricity, using a dam and a turbine.
  • Hydrogen as fuel: It can be obtained from biomass, natural gas, or electrolysis of water, but it is expensive and risky because it ignites easily.

International Commitments

  • Brundtland Report (1967): Gives a critical view of the development model of industrialized countries and defines sustainable development.
  • Conference on Environment and Development in Rio de Janeiro (1992): Commitments are made on climate change and biodiversity, and sustainable development strategies.



Geological History

  • A. Holmes (1945) proposed a theoretical model of convection currents in the mantle as the cause of continental drift and the continuous formation of oceanic crust. During World War II, the seabed was explored, and dorsals were found.
  • H. Hess (1962) formulated a hypothesis of the expansion of the ocean floor: it is created at the ridges, moves, and is destroyed at subduction zones.



Static Model of the Earth’s Interior

  • Crust: Formed by rocks (silicates of aluminum, calcium, sodium, and potassium), 2 types:
    • Continental crust: Thicker, made of sedimentary, metamorphic, and magmatic rocks.
    • Oceanic crust: Thinner, denser, made of basaltic rocks and gabbros.
  • Mantle: Formed by a special type of rock (peridotite) with two discontinuities.

Tectonic Plates

The crust and upper mantle form a rigid and brittle unit (lithosphere, about 100km thick). This is fragmented into pieces (lithospheric plates). Each plate consists of oceanic lithosphere or mixed, and they are limited by plate boundaries that can be: ridges, subduction zones, or transform faults. These plates float on the upper mantle (they move, are created, and destroyed). They are created in the ridges and destroyed at subduction zones, and the engine is the Earth’s internal heat.

  • Ocean ridges: Magma constantly emerges from them; the edges are constructive because when magma cools and solidifies, it forms rock (basalt). Transform faults fragment these ridges, and their movement creates earthquakes.
  • Subduction zones: Destructive edges sink at the bottom of the oceans, where the lithosphere is destroyed, forming oceanic trenches. As it moves away, it ages, cools, becomes thinner and denser, and sometimes it sinks and returns to the mantle. They describe an inclined plane (Benioff plane) and generate seismic sources as they melt and feed volcanoes.
  • Transform faults: Neutral edges (neither created nor destroyed) are tears that appear in areas subjected to different thrusts, allowing the plates to slide relative to each other (in opposite directions) without volcanic activity but with seismic activity.

The Engine that Moves the Plates

Gravity pull together with internal heat:

  • The main flow is due to the subduction of oceanic lithosphere, which cools in the upper mantle and descends to the D” layer, causing the ascent of hot material through convection. This is possible due to the high pressure and temperatures.
  • The second convective flow is when much of the heat accumulated in the D” layer escapes in spurts, and each bubble causes a jet or plume of magma that rises through the mantle, drilling the lithosphere and creating a hot spot.


The Theory of Plate Tectonics

A global theory, stating that major geological phenomena (volcanism, mountain building, etc.) have a joint explanation, motivated by a common cause: the Earth’s heat helped by gravitational potential energy.

  • Earthquakes: In subduction zones, oceanic ridges, and transform faults, large masses of rocks collide. If they affect the continents, they cause earthquakes; at sea, they cause tsunamis (if a large wave occurs).
  • Volcanoes: In ridges, subduction zones, and hot spots, magma escapes through cracks and forms volcanoes.
  • Formation of mountains: The thrust of the sinking plate smashes the sediment accumulated in subduction zones, folds and fractures it, and then it rises, forming large mountain ranges.
  • Expansion of the oceans: Oceanic lithosphere is continuously created on both sides of the ridges, and the oceans are becoming larger.
  • The drift of the continents: The continents are part of the lithospheric plates that move; sometimes they split up, and other times they collide.
  • Non-combustible minerals and oil: Plate tectonics helps predict the location of oil and natural gas deposits and minerals.

Volcanoes

Formed when magma from the mantle rises to the surface through fissures in the oceanic and continental crust, cools, and gives rise to eruptions of gas, liquid, and solid products: lava (molten rock). Volcanoes are located within the plates in hot spots, ridges, and subduction zones.

  • Volcanism in hot spots: Where a magma plume reaches the lithosphere, it acts as a torch and originates a hot spot. 3 situations:
    • Drilling of the oceanic lithosphere and the appearance of a chain of volcanoes; the hot spot remains fixed, and the lithosphere is drilled as it scrolls.
    • Origin of large igneous provinces or basaltic areas buried by basaltic lava on the planet.
    • Thinning of the continental lithosphere and formation of a rift; it acts like a blowtorch on the lithosphere, which bulges and thins to form 3 radial fractures that converge at a point (triple point); they can become depressed.
  • Volcanism on oceanic ridges: Along the ridges, in the depths of the oceans, there are volcanoes, fissure eruptions with quiet lava that flows from large cracks, and when cooled, it causes basaltic rocks.
  • Volcanism in subduction zones: Found in the Pacific Ring of Fire, volcanoes are shaped like a huge cone that can be formed by the accumulation of solid fragments that do not cohere, or by the superposition of layers of solidified lava. 2 cases:
    • Subduction of oceanic lithosphere below oceanic lithosphere leads to an archipelago of islands in an arc of intense volcanic activity.
    • Oceanic lithosphere subduction beneath continental lithosphere results in a continental volcanic arc (associated with a mountain range).

Volcanic Eruption

A set of phenomena that occurs when magma reaches the Earth’s surface. When magma is close to the surface, it forms a waterproof bag called a magmatic chamber. The gases dissolved in the magma are released, increasing the pressure and pushing the magma. This magma goes up through channels (chimneys) and out the crater. As it cools, it can cause:

  • Fluid magmas, low gas content, form lava flows, quiet eruptions.
  • High viscous magma, high gas content, gas escapes brutally in violent explosions, throwing off chunks of lava and fragments (pyroclastics) of the chimney (ash <3 mm, lapilli 3 to 30 mm, and volcanic bombs from 3 to 30 cm).

Earthquakes

Generated at the ridges, subduction zones, and transform faults, they are due to brutal ground shaking caused by the fragmentation of rocks at depth, releasing high energy slowly accumulated over the years. On land, they are called earthquakes; at sea, tsunamis.

Seismic Waves

Generated in a specific part (focus or hypocenter) at several kilometers depth, after a time, they can be captured by seismographs that record the arrival of waves.

Types of Seismic Waves

  • P or primary waves: Compression waves in rocks that cause compression and expansion, backward and forward.
  • S waves or secondary: Transverse waves that move up and down.
  • L or surface waves: When the S and P waves arrive at the epicenter, they generate surface waves.

Magnitude and Intensity of an Earthquake

For evaluation:

  • Richter Scale: Objective, measures the magnitude of an earthquake, the energy released by an earthquake (measuring the maximum amplitude of P and S waves), without limits (1, 2, …).
  • MSK Scale: Measures the intensity of an earthquake, a subjective estimation of the effects it produces on people, objects, buildings, and terrain. It varies in each place and with the distance from the epicenter. Magnitude is unique, and intensities are different in each location.

Paleomagnetism

Volcanic rocks are best for studying it, and when lava solidifies rapidly, certain minerals are magnetized according to the direction of the Earth’s magnetic field at that time.

Subduction Zones

Referred to as destructive or convergent edges because they are areas where oceanic lithosphere is constantly being destroyed as the two plates converge and collide as they move in opposite directions. The process gives rise to intense seismic and volcanic activity and the formation of oceanic trenches, island chains in arc shapes, and orogeny or mountain ranges.

  • Subduction of oceanic lithosphere beneath oceanic lithosphere: The formation of an oceanic trench at great depth. When engulfed by the mantle, the subducting plate partially melts and causes magma. Part of it rises to the surface through cracks and results in arc-shaped islands with high volcanic and seismic activity.
  • Oceanic subduction of lithosphere beneath continental lithosphere: Orogenic mountain ranges extend hundreds or thousands of kilometers along the edges of the plates that converge and give rise to orogenic belts because they arise through the folding of large amounts of sediment from the erosion of nearby continents.
  • Intercontinental collision




Natural Hazards

Any natural process that is a threat to human life or property.

Analysis and Planning of Risk

  • Danger: The probability of occurrence of a phenomenon that can cause damage to a specific place within an area of time. It is measured by degrees from 0 to 4 in magnitude. The return period is also measured, how often it is repeated (1/200) every 200 years.
  • Vulnerability: Missing damage, lost lives, and economic losses. 0 absence, 1 low, 4 total. Japan has good buildings.
  • Exposure or value: The number of people or goods exposed to a particular risk. Japan has many people, so it is high.
  • Planning: To develop measures, which can be:
    • Prediction: To know when, where, and how a phenomenon occurs. Risk maps are prepared based on historical data.
    • Prevention and correction: They can be structural (geological structures are changed or construction) and non-structural (civil protection and evacuation plans).

Volcanic Risk Factors

The type of eruption determines the risk factor, which is taken into account along with the frequency of eruptions, which depends on the physical characteristics of the lava (viscosity and quantity of gases).

  • Hawaiian Eruption: Low viscosity and little pyroclastic material, minimum explosions.
  • Strombolian eruption: Thick lava but little shooting.
  • Vulcanian Eruption: Emitting very little flowing lava and very viscous, breaking the cap as they dry faster.
  • Plinian eruption: Very viscous lava and very violent explosions.

Exposure Factor

The size of the affected population; if there are no people in the range of the volcano, and also the property, crops, etc.

Risks

Several: emission of toxic and poisonous gases (sulfur derivatives) and lahars (flows of mud and mud caused by the melting of ice and snow).

Prevention

Decrease or eliminate the risk of volcanic effects. The prohibition of human settlements in areas of higher risk, sloping roofs, making shelters, or evacuation plans.

Volcanic Risk Areas

These areas are around the boundaries of the plates and some intraplate points: subduction zones (many volcanoes) as those that surround the Pacific Ocean; archipelagos of island arcs as in Japan; continental rifts (Africans); islands located on oceanic ridges (Iceland); and hot spots like Hawaii. In Spain, assets remain in the Canary Islands (last eruption in 1971), inactive in Olot (Girona), Cabo de Gata (Almeria), etc.

Seismic Hazard

  • Seismic Cycle: Explains that there is a drop in elastic stress after an earthquake and a buildup of tension before the next (it is repeated cyclically). The tension is the deformation caused by the pressure (and that breaks the rocks). In doing so, the broken ends bounce, releasing stored energy (elastic rebound). The seismic cycle has 4 phases:
    1. A long period of inactivity with accumulated elastic strain.
    2. Small jerks sometimes occur just before the big earthquake.
    3. The main earthquake and aftershocks.
    4. Produces small earthquakes.
  • Seismograph: Seismic waves are recorded with this instrument that provides a graphic.
  • Seismogram: Where the strength of the earthquake is reflected.
  • Seismic Magnitude: A measure from which to calculate the energy an earthquake releases. C. F. Richter developed a linear seismic magnitude scale. No, an earthquake of 6 is 10 times one of 5. From 8, they are devastating.
  • Seismic Intensity: A measure of the effects or damage that earthquakes cause in structures or sensations perceived by people. G. Mercalli created the scale from Roman numeral 1 to 12, and then it was amended.

Design of Seismic Risk

  • Prediction Measures: In the short term, there is no reliable method. In the long term, the probability of occurrence of a certain magnitude and a prediction interval is estimated. For this, ground deformation, long periods without earthquakes, abnormal behavior in animals, and proliferation of micro-earthquakes are studied.
  • Prevention: To reduce exposure and vulnerability.
    • Structural: Earthquake-resistant construction standards (in areas at risk) with steel buttresses, others that behave as a unit, and others that make insulating foundations with shock absorbers.
    • Non-structural measures: Spatial planning, civil protection, and teaching how to behave in an earthquake.

Tsunami

Or the massive accounting for the vertical displacement of a huge mass of ocean water. This is usually the result of a major earthquake, with an epicenter in the sea (tidal wave), the collapse of part of a volcano (in the ocean), an underwater volcanic eruption, or an asteroid impact at sea.

Prediction of Tsunamis

These systems consist of gauges and tsunamometers, floating buoys to detect sea-level rise and likely to build one.

Salt Diapirs

Originate from the existence of masses of salts (halite, gypsum), which ascend due to their low density and cause instability of the ground (buildings). It is necessary to prevent water from leaking or inject solid materials.

Sinkholes

Sudden collapses, typical of karst areas, where materials dissolve easily (limestone and gypsum), and there are hollows underground, caves, etc. It can also happen due to mining extraction. Subsidence is slow subsidence, not collapses, in soft ground (clay), caused by the extraction of fluids, water, oil. For prediction, geophysical methods are used.

Expansive Soils

Soils that quickly change volume (swelling by hydration and shrinkage when they lose water) in clays.

Movements of Sand Dunes

These can invade villages, fields, and communication routes. Prevention: build barriers and revegetation to fix and stop the advance.

Landslides

Gravitational movements of materials on the surface that cause significant damage.

  • Factors:
    • Natural: Slope, saturation of the ground with water by filtration, etc.
    • Anthropogenic: Human activities can remobilize, deforestation, and urbanization facilitate the circulation of water, etc.
  • The movements can be:
    • Avalanches: Quick mass movements of soil or rock fragments.
    • Landslides: Falls of rock blocks by gravity.
    • Flows: Loose materials that behave almost as fluids.
    • Landslide: Rock mass movements on the fracture surface (a fault).

Avalanches

Displacement of masses of snow in areas of high slope. Due to rainfall, increased temperature, displacement of cracks, vibrations, explosions, etc.

  • Prediction measures: Study of slopes: marks that indicate displacements, strains, etc.
  • Preventive measures: To control mass movements: containment measures (walls, nets, anchors), drains to lower the avalanche of water, and revegetation.

Climate-Related Risks and Weather

  • Tropical Cyclone, Hurricane, and Typhoon: General term that refers to large storms that rotate around a low-pressure area, which form in the warm waters of tropical oceans. Low-intensity tropical storms, but if the wind is over 118 km/h, it is a hurricane. Hurricanes are formed when water is over 26°C, the water evaporates, the steam rises and condenses as clouds, and the release of energy brings strong winds and much rainfall. These winds are around a relatively calm area (eye), in the northern hemisphere counterclockwise and in the south clockwise. The grades range from 1 (118 km/h) to 5 (+ 248 km/h).
  • Tornadoes: Violent windstorm characterized by a rotating funnel cloud. During thunderstorms, when cold air is spread over warm air, forcing the heat to rise quickly.
  • Cold Drop: Occurs in late summer and early autumn. When a cold air pocket is at a certain height, it surrounds itself suddenly with hot air; the cold, dense air descends toward the surface and forces the hot, humid air to rise, forming a cloud (heavy rains).
  • Floods: In coastal areas or riverbeds. Causes or accelerates floods: heavy rain in a short time, long rains, a river damming by landslides, destruction of a dam, sea level rise by tsunamis, asphalt that prevents water from filtering. It is measured with the formula: Q = AV, where Q is the flow rate, A is the surface in square meters, and V is the velocity in m/s.
  • Prediction measures: Exploring the return period (to develop risk maps) and weather reports.
  • Prevention:
    • Structural: Work on the runways, construction of dams, increased channel capacity, diversion channel, reforestation.
    • Non-structural: Laws prohibiting certain uses and activities in these areas, civil protection plans, and life insurance.