Multi-Hazard Environments

Some places are exposed to multiple natural hazards simultaneously or sequentially. Understanding why certain regions are 'hazard hotspots' and how overlapping risks compound vulnerability is a key component of AQA A-Level Geography. This lesson examines the concept of multi-hazard environments, the Philippines as a case study, and theoretical models for analysing hazard impacts and responses.

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What Is a Multi-Hazard Environment?

A multi-hazard environment is a location exposed to two or more types of natural hazard. These may be:

• Geophysical — earthquakes, volcanic eruptions, tsunamis, landslides
• Atmospheric/hydrological — tropical storms, floods, drought, tornadoes
• Compound — hazards that trigger secondary hazards (e.g., an earthquake triggering a tsunami and landslides, or a volcanic eruption triggering lahars during heavy rain)

Hazard Hotspots

Certain regions face disproportionately high hazard exposure due to their tectonic setting, climate, and physical geography:

Hotspot	Tectonic Hazards	Atmospheric Hazards	Other
Philippines	Earthquakes, volcanic eruptions, tsunamis	Typhoons, flooding, drought	Landslides, storm surge
Japan	Earthquakes, volcanic eruptions, tsunamis	Typhoons, flooding	Landslides
Caribbean	Earthquakes, volcanic eruptions	Hurricanes, flooding	Landslides, storm surge
Bangladesh	Earthquakes (northern region)	Cyclones, monsoon flooding, drought	River bank erosion, storm surge
Indonesia	Earthquakes, volcanic eruptions, tsunamis	Flooding, drought	Landslides, forest fires

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Case Study: The Philippines as a Multi-Hazard Environment

Tectonic Setting

• Located on the Pacific Ring of Fire at the junction of several tectonic plates (Philippine Sea Plate, Eurasian Plate, Pacific Plate)
• Contains 23 active volcanoes (including Pinatubo, Mayon, and Taal)
• Experiences frequent earthquakes — a Mw 7.2 earthquake struck Bohol in October 2013, killing 222 people and destroying 73,000 homes
• Vulnerable to tsunamis generated locally or from distant Pacific earthquakes

Atmospheric Hazards

• Lies in the western Pacific typhoon belt — an average of 20 typhoons enter the Philippine Area of Responsibility each year, with ~8–9 making landfall
• Heavy monsoon rainfall causes widespread flooding and landslides
• El Niño years bring severe drought to parts of Mindanao and the Visayas

Compounding Vulnerability

The Philippines' hazard exposure is amplified by:

• Poverty — approximately 18% of the population lives below the national poverty line; informal settlements on flood plains and unstable slopes
• Rapid urbanisation — Metro Manila (population ~13 million) is highly exposed to earthquakes, flooding, and typhoons; inadequate drainage infrastructure
• Deforestation — illegal logging on steep slopes increases landslide risk and reduces natural flood buffering
• Coastal settlement — 60% of the population lives in coastal areas, exposed to storm surge and tsunamis
• High population density — over 110 million people on 7,641 islands

Disaster Timeline (Demonstrating Multi-Hazard Frequency)

Year	Event	Impact
1991	Mount Pinatubo eruption (VEI 6)	847 deaths; 200,000+ displaced
2006	Typhoon Durian / Mudslide from Mayon Volcano	~1,400 deaths
2009	Tropical Storm Ketsana (Ondoy)	Over 400 deaths; Metro Manila flooded
2013	Bohol earthquake (Mw 7.2)	222 deaths
2013	Typhoon Haiyan (Yolanda)	6,300 deaths; 4.1 million displaced
2020	Taal Volcano eruption	~590,000 evacuated

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Theoretical Models for Analysing Hazard Impacts