Measuring tropical cyclones using the Saffir-Simpson Scale

Tropical cyclones, also known as hurricanes or typhoons in different regions, are powerful storms that can be tracked and measured with precision thanks to global satellite systems and weather stations. Their key characteristics, such as wind speed and rainfall, are continuously monitored, allowing for forecasts and early warnings that are not always possible with other natural hazards like earthquakes or volcanic eruptions.

Classification of tropical cyclones

Once a tropical storm's wind speed reaches 119 kilometres per hour (kph), it is classified as a cyclone. The Saffir-Simpson Scale is then used to categorise its strength based on several factors including wind speed, air pressure, storm surge height, and the typical damage caused.

The Saffir-Simpson Scale categories

Primary and secondary impacts of tropical cyclones

Tropical cyclones cause widespread destruction through a combination of intense winds, heavy rainfall, and storm surges. Their effects can be divided into primary impacts, which are the immediate results of the storm, and secondary impacts, which occur as a consequence of the initial damage.

Primary impacts

• Physical destruction - High winds, torrential rain, and coastal storm surges damage buildings, infrastructure, and property.
• Human toll - People are often injured or killed due to collapsing structures or flooding.
• Immediate disruption - Communities face interruptions to their daily lives, with transport links and services halted.

Secondary impacts

• Economic consequences - Businesses suffer losses, and the cost of rebuilding infrastructure can be substantial.
• Environmental damage - Landslides, soil erosion, and prolonged flooding disrupt ecosystems.
• Social and health issues - Loss of homes and possessions leads to displacement, while waterborne diseases can spread due to contaminated water supplies.
• Access challenges - Blocked transport routes from landslides or flooding hinder relief efforts, worsening the situation.

Global distribution of tropical cyclone hits

Tropical cyclones do not affect all regions equally. Certain countries experience these storms more frequently due to their geographical location in tropical and subtropical zones where warm ocean waters fuel cyclone formation.

Countries most affected by tropical cyclones since 1970

This ranking highlights how some nations, particularly in Asia and the Pacific, are repeatedly in the path of tropical cyclones, making preparedness and resilience critical.

Variations in casualty and economic losses across countries

While tropical cyclones strike many countries with similar frequency, the impact in terms of human casualties and economic damage varies significantly. Factors such as economic development, infrastructure quality, and disaster preparedness influence these differences.

Casualty figures in Asia and Pacific countries

Data from countries in the Asia and Pacific region shows stark contrasts in the human cost of tropical cyclones, even among nations with a high number of storm hits.

Economic losses in Asia and Pacific countries

Economic impacts also vary widely, often reflecting a country's ability to absorb financial shocks and rebuild after a disaster.

Countries like Japan, despite frequent cyclone hits, report fewer casualties compared to China or the Philippines. This disparity likely stems from Japan's status as a developed nation with advanced warning systems, stronger building standards, and effective disaster response mechanisms. Economic losses also tend to be lower relative to the frequency of storms in more developed countries due to better infrastructure and recovery capabilities. In contrast, developing nations often face higher human and economic tolls due to limited resources for preparation and recovery.