The impacts of natural hazards Revision Notes

Tectonic hazards include earthquakes, volcanic eruptions, tsunamis, landslides, and fires triggered by seismic activity. These events can cause widespread destruction to buildings, roads, bridges, and other infrastructure, leading to displacement of people and disruption of essential services such as electricity and water supply.

For example, an earthquake may cause buildings to collapse, resulting in fatalities and injuries. The destruction of transport routes hinders emergency response and aid delivery.

Tsunamis generated by undersea earthquakes can flood coastal areas, destroying habitats and agricultural land. Landslides triggered by seismic shaking can bury homes and farmland, further reducing available land for food production and natural habitats. Fires following tectonic events can spread rapidly, damaging ecosystems and increasing air pollution. Psychological trauma is common among survivors due to loss of loved ones, homes, and livelihoods. Waterborne diseases often increase after tectonic disasters because damaged sanitation systems contaminate drinking water sources, leading to outbreaks of illnesses such as cholera. Economically, the cost of rebuilding infrastructure and homes can be enormous, affecting national and local economies for years.

• Structural damage to buildings, roads, and bridges.
• Fatalities and injuries from collapsing structures.
• Loss of agricultural land and natural habitats due to landslides and tsunamis.
• Increased risk of waterborne diseases from contaminated water supplies.
• Psychological trauma among affected populations.
• Economic losses from reconstruction and disrupted services.

Tropical cyclones are intense storms characterised by strong winds and heavy rainfall. The high winds can damage or destroy buildings, power lines, and transport infrastructure, causing widespread disruption.

Heavy rainfall often leads to flooding, which can submerge homes and farmland. Floodwaters can kill people and livestock, destroy crops, and contaminate drinking water supplies, increasing the risk of waterborne diseases such as dysentery.

Loss of crops and habitats reduces food availability and harms biodiversity. For example, a cyclone striking a coastal farming community may destroy rice paddies and mangrove forests, which serve as natural storm barriers and wildlife habitats. Fatalities occur due to drowning, injuries from debris, and secondary health effects. The economic impact includes costs of rebuilding, loss of income from damaged agriculture and fisheries, and reduced tourism.

• Damage to structures and infrastructure from strong winds.
• Flooding caused by heavy rainfall.
• Fatalities from drowning and injuries.
• Loss of crops and natural habitats.
• Outbreaks of waterborne diseases due to contaminated water.
• Economic losses from damage and disrupted livelihoods.

Flooding can result from heavy rainfall, river overflow, storm surges, or dam failures. It causes immediate threats to life through drowning and injuries. Floodwaters can destroy homes, roads, and bridges, isolating communities and hindering rescue efforts.

Livestock and crops are often lost, reducing food supply and income for farmers. Floodwaters frequently contaminate drinking water with sewage and chemicals, leading to outbreaks of diseases such as typhoid and cholera.

The economic costs include repair and replacement of damaged infrastructure, loss of productivity, and increased healthcare expenses. For instance, a river flood in a rural area may submerge fields for weeks, killing crops and eroding soil fertility, which affects future harvests.

• Fatalities due to drowning and accidents.
• Loss of livestock and destruction of crops.
• Damage to buildings, roads, and bridges.
• Contamination of drinking water supplies.
• Increased incidence of waterborne diseases.
• Economic losses from repair costs and reduced productivity.

Droughts are prolonged periods of below-average rainfall leading to water shortages. They cause deaths of plants and animals unable to survive without sufficient water, reducing biodiversity.

Water sources such as rivers, lakes, and reservoirs become depleted, affecting drinking water availability for people and livestock. Crop yields decline due to lack of soil moisture, leading to food shortages and starvation in severe cases.

Soil erosion increases because dry soil is more easily blown or washed away, which can lead to desertification — the permanent loss of productive land. Poor air quality results from dust storms and increased wildfires, which are more likely during dry conditions. For example, a drought in a semi-arid region may cause farmers to lose their harvests and livestock, forcing migration and economic hardship.

• Deaths of plants and animals due to water scarcity.
• Depletion of water sources for human and animal use.
• Reduced crop yields causing food shortages and starvation.
• Increased soil erosion and risk of desertification.
• Poorer air quality from dust and wildfires.
• Higher risk of wildfires spreading rapidly.