1-3-2-multiple-hazard-zone-case-study

Multiple-Hazard Zone Case Study

• There are many areas in the world which are vulnerable to multiple hazards

• When two or more hazards occur at the same time or in rapid succession the area faces:

  • Dealing with a new hazard event whilst still recovering from a previous hazard event

  • Issues with development due to the costs of recovering from multiple hazard events

The Philippines

• The Philippines is an island nation situated in Southeast Asia in the Western Pacific Ocean

• It is an archipelago consisting of over 7,600 islands

• The capital is Manila 

• The population is estimated at 115.6 million (2022) with a population density of 385.2 people per km²

• Almost 50% of the population is urban

• An estimated 74% of the population and 60% of the land area is vulnerable to hazard events

• In 2019 and 2020 the Philippines experienced 4 typhoons, the eruption of the Taal volcano and a number of earthquakes

Tectonic activity

• The Philippines are located at the boundaries of a number of major and minor plate boundaries 

• It is on the western edge of the Pacific Ring of Fire

• These are mainly convergent boundaries leading to both volcanoes and earthquakes

Volcanoes and earthquakes

• There are a number of subduction zones around the archipelago which has led to significant volcanic activity

  • There are 24 active volcanoes on the islands 

  • The eruption of Mount Pinatubo in 1991 was until recently the largest eruption in the last 100 years

  • Approximately 2.81 million people live within 30km of the Taal volcano 

  • Mount Mayon has erupted over 50 times in the last 500 years

Tsunami

• The location in the Western Pacific makes the Philippines vulnerable to tsunami

• Tsunami may result from both volcanic eruptions and earthquakes

• The worst tsunami in recorded history occurred in 1976 when tsunami waves of up to 5 meters struck Lebak in the southwest of the Philippines

Typhoons

• The Philippines is located between 5^o and 20^o north of the equator and lies in the tropical cyclone zone

• Typhoons can occur at any point in the year 

  • The most active months are June to September

• The islands are affected by between 15-20 typhoons a year

• The most powerful typhoon to strike the Philippines in recent years was Typhoon Yolanda (also known as Haiyan) in 2013

  • Wind speeds reached 315km/h and 6,500 people were killed

Landslides 

• The mountainous landscape of the Philippines means that landslides are common

• Earthquakes, volcanic eruptions and typhoons can all trigger landslides

Vulnerability

• Increased urbanisation has led to high population densities in cities such as Manila

• The population is mostly coastal as inland areas are mountainous, this increases the vulnerability to storm surges, typhoons and tsunami

• Increasing population has led to deforestation in the upland areas as a result of clearance for settlements and agriculture

  • Deforestation increases the risks of landslides as there is less interception and more surface runoff

• More settlements have been built in areas of high risk, Angeles was built near Mount Pinatubo before the eruption in 1991

• The Philippines is a developing country, it lacks money for planning and preparation

  • The GDP per capita is US$3,460 compared to the USA which is US$70,248