Earthquakes, Volcanoes, Energy and Water: Key Natural Hazards and Resources

T.8: Natural Hazards and Risk Management

Earthquakes

An earthquake is the vibration of the Earth's surface caused by the sudden release of accumulated energy in rocks subjected to stress until they reach failure, causing fractured and displaced rocks.

Seismic risk criteria

• Location in relation to the limits of tectonic plates and the area
• Local geological characteristics
• Presence and length of active faults
• Area seismic history
• What happened in the past to predict the future

Tsunami

Tsunami waves are produced by a large volume of water displaced by a sudden, large vertical movement of the sea floor beneath the epicenter. This movement displaces a large volume of water that rises to the surface and spreads outward. The higher the volume of water, the higher the wave, and as it spreads it loses intensity while reaching distant zones. Tsunamis usually cause the first casualties in the first minutes after the earthquake.

Volcano

A volcano is a landform on the terrestrial surface where magma, gases and materials from inside the Earth emerge.

Dangers of volcanoes include:

• Emission of toxic gases or ardent clouds
• Formation of pyroclastic flows
• Explosions
• Mudflows
• Lava flows

Warning signs (precursors):

• Frequent local seismic activity
• Changes in the inclination of the terrain
• Variation in the temperature of springs and wells
• Increase in gas emissions

Flooding

Flooding occurs when zones normally dry are covered by water, often because of torrential rains that cause rivers to overflow. Runoff can cause flooding.

Risk induced by:

• Occupation of flood-prone zones next to the river channel
• Flood-prone zones are natural regulators and their occupation is not the main cause
• Infiltration and deforestation reduce runoff and increase the possibilities of flooding, as covered soil and waterproof surfaces limit infiltration
• Infrastructure works can interfere with water flow and make evacuation difficult

Gravitational processes and slope movements

A displacement of material toward the bottom of a slope under the direct action of gravity. Examples include falls of material in free fall, and displacements such as viscous fluid flows or the movement of blocks resembling a fluid on the surface.

Hurricane

A tropical cyclone is the most violent of storms. Strong winds form a large spiral around a relatively calm eye.

T.9: Efficient Energy Consumption

Efficient energy consumption consists of developing energy-consuming tasks in a way that minimizes energy waste and unnecessary energy use.

Energy

• Primary energy is contained in energy sources.
• Final energy is the energy used by consumers.
• Formula: Ep = Ef + perdidas en transporte + pérdidas en operaciones

Transport

Transport consumes energy and is responsible for about 25% of free CO2 emissions in the atmosphere.

Efficient measures:

• Increase the use of public transport: trains, buses, bikes
• Efficient driving, appropriate speed, proper vehicle maintenance
• Lower consumption of vehicles and lower fuel use
• Better aerodynamics in vehicle design
• Development of alternatives to fossil fuels such as biofuels, and new propulsion systems such as hydrogen and electricity

Biofuels

• Biodiesel: made from oleaginous seeds and used vegetable oils
• Bioethanol: produced by fermenting plants rich in starch or sugar
• Biogas: produced by fermentation of animal and plant waste

Energy sources according to their origin

The main source is oil. Electric energy covers about one third of electricity consumption, along with natural gas and coal.

Energy consumption depends on:

• Climate of the area
• Insulation of buildings
• Equipment used
• Degree of efficiency

Electric power:

Electricity is produced on a large scale and distributed through transformer stations to users. Fossil fuels such as petroleum, coal and natural gas are used.

Nuclear energy

Nuclear energy is released through fission of heavy elements such as uranium.

• Problems: risk of accidents, as in Chernobyl (1986), radioactive waste produced in plants, and the risk of technology being used for weapons development.
• Solutions: it does not emit greenhouse gases, produces continuous energy at lower cost than oil, reduces dependence on imports, and in a central area the probability of accidents is low.

Solar energy

Solar energy is a direct, renewable source. Its advantages include:

• Thermal: high temperature for industrial uses and low temperature for heating water through solar collectors
• Photovoltaic: converts sunlight directly into electricity

Biomass

Biomass is organic matter of plant or animal origin. Biofuels produce heat for domestic use in boilers and hot water.

Wind energy

Wind turbines in wind farms produce electricity from the movement of their blades.

Hydroelectric energy

Hydroelectric plants harness the water of rivers and reservoirs to drive turbines and produce electricity, though reservoirs have environmental impacts.

Tidal energy

Tidal energy uses the rise and fall of tides.

Geothermal energy

Geothermal energy uses heat accumulated in the subsoil.

Advantages of renewable energy

• Low environmental impact and few pollutants
• Inexhaustible sources
• Reduces dependence on external energy and consumer costs
• Its research contributes to scientific and technological development of the country

Disadvantages

• Some sources are unstable and depend on weather conditions, so they do not guarantee a constant supply
• Some have negative environmental impacts, and may cover only a small percentage of demand

Sustainable energy model

A sustainable model allows current generations to meet their energy needs while guaranteeing the same for future generations. Its ways include: energy efficiency, technological development, promotion of renewable energy, and development of new energies.

Future energy

Hydrogen, marine energy and nuclear fusion.

T.10: Water

Only about 1% of the planet's water is directly usable by humanity. Water is the greater component of living beings, a basic element of biological reactions, and helps the body maintain its temperature.

Water as a resource

Water is a natural resource used for human interests. Its capacity for regeneration determines its use.

• Renewable resource: forms part of natural cycles and regenerates without human intervention, unless its capacity is exceeded.
• Non-renewable resource: does not regenerate after use and is depleted.

The water cycle

Evaporation, condensation and precipitation, surface runoff, infiltration, evapotranspiration and underground runoff.

Available water

The volume of precipitation minus losses through evapotranspiration.

Consumptive uses

Consumptive uses involve water that is no longer available after use: domestic use in homes, agricultural use for irrigated crops, public services and industrial uses such as paper manufacturing.

Non-consumptive uses

Non-consumptive uses do not consume water: energy production, recreation (sports and leisure), industry and ecological uses such as refrigeration.

Water flow

Flow is the amount of water that moves downstream, which is essential for the survival of fauna, flora and aquatic ecosystems.

The water cycle of use

Water use involves uptake, transport, treatment, distribution and purification.

Environmental impact

Human activities affect the natural environment, and this affects the quantity and quality of water.

Contamination

Contamination is any undesirable change in the characteristics of ground or surface water that makes it harmful to food, health, or the survival of living beings and sports activities. It can come from:

• Urban: domestic and industrial wastewater
• Industrial: waste from production processes
• Agricultural: fertilizers and pesticides

Water stress

Water stress occurs when demand for water is greater than the available supply or its quality is insufficient.

Aquifers

An aquifer is a porous rock layer in the subsoil that stores water. Water infiltrates and is stored in it.

Water table

The saturated level in an aquifer zone.

Sustainable water management

Water can be used sustainably if demand and availability are kept in balance. Availability increases with reservoirs, water transfers and desalination.

Recommendations for managing this resource are: encourage savings, improve efficiency, and encourage reuse.