Understanding Natural and Technological Risks: Mitigation and Prevention

Posted on Dec 25, 2024 in Geology

Understanding Natural and Technological Risks

Distinguishing Between Phenomena and Disasters

A tsunami is a natural phenomenon, like a hurricane or a flood. However, a disaster is any event or process that causes damage to humans, materials, or the environment.

Types of Risks

There are various types of risks:

  • Technological: Caused by human activities, accidents, or infrastructure failures (e.g., a plane crash).
  • Cultural: Risks that occur in daily life (e.g., food poisoning).
  • Natural: These include biological, chemical, geological, and cosmic risks.
  • Mixed: Natural risks intensified by human actions.

Risk Factors

There are three main risk factors:

  1. Danger: Depends on the intensity, frequency, and distribution of the hazard.
  2. Exposure: Can be social, economic, or ecological.
  3. Vulnerability: Represents the susceptibility to harm.

Earthquake Risk Assessment

Two earthquakes of the same magnitude may have different risk values. The magnitude of risk depends not only on the natural phenomenon but also on human decisions that determine where the population is located, their property, and under what conditions they live.

Prediction vs. Prevention

Prediction relies on statistical data indicating whether a phenomenon is common in an area. It also considers precursors that warn of the proximity of an event. Prevention, on the other hand, involves adopting necessary measures so that if the event occurs, it has minimal effects on the population or its assets.

Earthquake Intensity vs. Magnitude

The intensity of an earthquake is the measurement of its effects on objects. Each earthquake has one magnitude, but its effects are greater at the epicenter. Therefore, the intensity decreases as we move away from the epicenter.

Seismic Risk Mapping and Mitigation

Seismic risk maps should consider not only the location or area of a plate boundary but also:

  • Local geological features, such as existing materials.
  • The presence of active faults and their length.
  • The seismic history of the area.

Preventive Measures for Earthquakes

  • Develop seismic risk maps to adjust preventive regulations.
  • Establish earthquake-resistant construction standards.
  • Implement land-use planning to limit construction along rivers.

Tsunami Characteristics and Warning Systems

Tsunamis have unique characteristics:

  • They move a huge volume of water from the surface to the bottom.
  • They propagate with little loss of intensity, affecting remote areas.
  • The sea often recedes minutes before the arrival of large waves.

A tsunami warning system operates as follows:

  1. Seismographs detect the earthquake and send information to a central computer.
  2. If the magnitude is greater than 6.5, the central computer warns countries in danger.
  3. Floating sensors detect the tsunami and send its characteristics to the central computer.
  4. The central computer processes the information, predicts the propagation speed, and transmits the alert signal to affected areas.

Volcanic Activity: Types and Products

There are different types of volcanic activity:

  • Acidic: Viscous lava causing explosive activity.
  • Basic: Fluid lava causing effusive and quiet activity.

Volcanic products include:

  • Liquids: Lava.
  • Gases: Carbon dioxide, sulfur compounds (many are toxic).
  • Solids: Range from ash to gravel.

Volcanic Hazards

Volcanic hazards include:

  • Emission of toxic gases (e.g., 10,000 deaths in Iceland in 1783).
  • Formation of burning clouds or pyroclastic flows (e.g., 28,000 deaths in the eruption of Mont PelĂ©e in 1902).
  • Explosions accompanying the eruption.
  • Mudflows (e.g., 21,000 deaths in Nevado del Ruiz).
  • Lava flows, which generally generate few victims.

Signs of an Impending Eruption

  • Small local earthquakes.
  • Changes in the slope of the terrain.
  • Rising water temperature in the area.
  • Increased emission of greenhouse gases.

Flood Prevention

To prevent flooding in some areas, the land should be properly managed.

Roads or railway tracks can produce a barrier effect. Changes in land use can also contribute to flooding.