Primary and secondary impacts of seismic hazards

Seismic hazards, such as earthquakes and tsunamis, result in immediate and cascading effects that can devastate communities and environments. These impacts are categorised into primary and secondary effects based on their direct or indirect nature.

Primary impacts of seismic hazards

These are immediate consequences caused by the hazard itself, such as people being killed when a tsunami hits a coastal area.

Secondary impacts of seismic hazards

These effects arise from primary impacts, such as earthquakes breaking gas pipes, causing fires.

Social, environmental, economic, and political effects of seismic events

Seismic events have wide-ranging impacts across various aspects of life and society.

Social effects of seismic events

• Human toll - Earthquakes can cause buildings to collapse, killing and injuring people, leaving others homeless.
• Utility failures - Earthquakes and liquefaction can cause gas leaks and power line failures, starting fires.
• Health risks - Lack of clean water can cause disease to spread.
• Widespread flooding - Tsunamis can flood large areas, killing people and causing widespread damage to property.

Environmental effects of seismic events

• Industrial damage - Industrial units including power plants can be damaged by earthquakes and tsunamis.
• Ecosystem destruction - Damage can cause leaks of chemicals or radioactive material that damage the environment. Fires started by damaged gas and electricity lines can destroy ecosystems.
• Soil and water contamination - Tsunamis can flood freshwater ecosystems, killing plants and animals and salinising water and soil.

Economic effects of seismic events

• Business disruption - Earthquakes can destroy business premises through ground shaking and liquefaction.
• Increased costs - Damage to industry may mean the country has to rely on expensive imports.
• Repair expenses - Damage to buildings and infrastructure can be very expensive to repair.

Political effects of seismic events

• Resource shortages - Shortages of food, water and energy can cause conflict and political unrest.
• Financial strain - Governments may have to borrow money to repair damage, putting the country in debt.
• Diverted funds - Money earmarked for development may have to be spent on repairing damage.

Short-term responses to seismic hazards

Immediate actions following a seismic event are critical to saving lives and addressing urgent needs.

Immediate actions following seismic events

• Rescue operations - Rescuing people from collapsed buildings after an earthquake.
• Evacuation measures - Evacuating people from areas at risk from a tsunami.

Long-term responses through prevention, preparedness, and adaptation

Beyond the immediate crisis, long-term strategies aim to reduce the risks and impacts of future seismic hazards. These responses are grouped into prevention, preparedness, and adaptation measures.

Prevention strategies for seismic hazards

• Limiting development - Authorities can prevent land prone to liquefaction from being built on.
• Protective barriers - Giant sea walls can prevent tsunamis hitting land.

Preparedness strategies for seismic hazards

• Early warning systems - Authorities can install earthquake warning systems that detect weaker seismic waves and send out alerts via radio and SMS.
• Tsunami readiness - Authorities can develop tsunami warning systems and evacuation routes.
• Community plans - Individuals and businesses can have plans for how people should respond during an earthquake, such as staying away from buildings if possible, finding a strong door frame or desk to shelter under if inside.
• Emergency teams - Communities can set up search and rescue teams or fire response units.

Adaptation strategies for seismic hazards

• Resilient architecture - Buildings can be designed to withstand earthquakes using strong or flexible materials, with special foundations that can absorb earthquake energy.
• Tsunami-resistant structures - Tall, strong buildings allow people to escape tsunamis quickly. Buildings with raised, open foundations are less likely to be damaged by tsunamis.
• Behavioural adjustments - People can adapt behavior or surroundings to minimize risks.