Natural Hazards: Earthquakes and Volcanoes
The Genetic Code
The genetic code defines the relationship between nucleotides in a polynucleotide and amino acids.
This code is universal, meaning all living organisms, from bacteria to humans, share it. This universality provides further evidence of the unity of life and our shared evolutionary history.
Four distinct types of nucleotides, represented by their bases, exist in nucleic acids. Proteins, on the other hand, are composed of 20 different amino acids.
Seismic Risk
Areas with high tectonic activity experience the greatest seismic activity. Other factors contributing to tectonic movement include volcanic activity, ground movement, explosions, fluid extraction and injection, and reservoir filling.
Large earthquakes can cause widespread devastation in a short period. Key characteristics of earthquakes include:
- Ground shaking and building collapse: Building collapse is the leading cause of death during earthquakes.
- Surface soil displacement: Displacement occurs along ground fault lines.
- Landslides: A powerful earthquake can trigger thousands of landslides, depending on the terrain.
- Tsunamis: These are series of fast-moving waves generated when a large mass of ocean water is violently displaced by the seafloor. Tsunami intensity is measured by wave height.
Earthquake Risk Prediction
Earthquake prediction methods involve monitoring ground shaking, ground deformation, changes in electric and magnetic fields, water levels in wells, and radon and other gas emissions along fracture lines. While these phenomena can indicate an impending earthquake, they can also occur without seismic activity, making them unreliable indicators.
Seismic Risk Prevention
The most effective earthquake prevention strategy involves identifying high-risk areas and implementing mitigation measures. Prevention focuses on ensuring the integrity of equipment and infrastructure to maintain essential services and aid delivery after a major earthquake. Damage reduction relies on specific measures in high-risk zones.
Volcanic Hazards
Volcanic hazards are often less apparent to populations near volcanoes due to long periods of inactivity, creating a false sense of security. However, volcanic eruptions are extremely dangerous and can lead to significant disasters.
The energy released during an eruption is comparable to an earthquake of magnitude 6 to 8.5, although the release is gradual rather than instantaneous.
The risk associated with volcanoes is amplified by the millions of people living in potentially hazardous volcanic areas, drawn by the fertile soil.
Volcanic Hazard Prevention
The primary method for preventing the effects of a volcanic eruption is predicting its occurrence. This requires continuous monitoring of the volcano to detect signs of an impending eruption.
The precursors to volcanic eruptions are similar to those of magma intrusion near the surface, making accurate eruption prediction challenging.
Only 1% of active volcanoes are adequately monitored with sensors and measuring instruments.
Assessing Volcanic Eruption Risk
- Seismic activity: Earthquake frequency near a volcano increases before it becomes active.
- Ground deformation: Inclinometers, GPS systems, and other tools measure ground uplift caused by rising magma.
- Changes in magnetic and electric fields and heat flux: These variations occur as magma rises to the surface.
- Gravity anomalies: Changes in gravity occur as magma ascends.
- Thermal vents: These vents are monitored for chemical changes related to magma movement.
Volcanic Dangers
- Explosive eruptions: The viscosity and gas content of the magma determine the explosivity of an eruption.
- Ejected materials: Materials projected into the air during explosive eruptions can affect large areas, depending on their height and wind direction.
- Lahars: These are avalanches of mud, lava, and debris formed by rapidly melting snow or ice, triggered by eruptions or rain.
- Lava flows: Fluid magma with low gas content forms large lava flows. While their impact is typically limited to a 30 km radius, they cause extensive damage and cover the ground.