Manila: A City Subject to Natural Hazards

Manila is located on the continent of Asia, more specifically, in the Philippines. This country is an archipelago of 7107 islands^[1].

The metropolis of Manila is the capital of the country. It is located on the island of Luzon, the largest in the archipelago. The city is on the western end of the island, on Manila Bay, and the Pasig River flows through it.

The Philippines is the third country in the world most exposed to natural hazards. As elsewhere in the country, Manila is located in a very high-risk area.

• It lies along the Pacific Ring of Fire.

• It is close to active volcanoes.

• It is located on a very active fault, which produces many earthquakes.

• It is located in a very high-risk tsunami zone.

• It is located on the trajectory of typhoons.

• It is crossed by the Pasig River, which represents a flood risk during heavy rainfall.

The capital region includes the city of Manila as well as what is referred to as Greater Manila. This is the name of the metropolis of Manila, which includes the neighbouring cities. Greater Manila covers an area of 633 km² and has a population of approximately 13 484 462 inhabitants^[2]. Consequently, its population density is 12,302 inhabitants/km².

The city of Manila has an even greater population density. With an area of only 38 km² and a population of approximately 1 780 148 inhabitants, its population density is 46 846 inhabitants/km^2[2].

In comparison, the metropolis of Montreal has a population of 912 inhabitants/km^2[3].
Manila’s high population density makes it a city that is particularly vulnerable to natural hazards because with so many people living there, natural disasters have greater human and material consequences.

There are many earthquakes in the Philippines. Not only is the country located in the Ring of Fire, but the archipelago also sits on the boundary of the Philippines’ tectonic plate.

The metropolitan area of Manila faces a moderate earthquake risk unlike most of the country, which is at high risk. The inhabitants of Manila often experience earth tremors, but most of the time these are weak tremors caused by earthquakes elsewhere in the country.

However, Manila is not completely safe from a possible earthquake. The major seismic fault known as the West Valley Fault is located very close to the metropolitan area. While there has been no movement for approximately 400 years, scientists believe that it will eventually cause an earthquake.

With such a high population density, an earthquake in Greater Manila could cause between 31 000 and 35 000 deaths^[7].

Manila is at a high risk of volcanic eruptions. The city is located close to two active volcanoes: Pinatubo, which is a little less than 100 km northwest of Manila, and Taal, 60 km to the south.

Taal is the second most active volcano in the Philippines. Because it is an explosive volcano, it expels clouds of ash and toxic gas covering many kilometres. It is the deadliest volcano in the country because it is located close to many inhabited areas.

Pinatubo is also an explosive volcano. In 1991, it erupted for the first time in more than 500 years. Its last eruption was in 1993.

Most of the Philippines is located in a high-risk tsunami zone while the metropolis of Manila is located in a moderate-risk tsunami zone. Although Manila has not experienced a tsunami in the last few years, it is nevertheless vulnerable.

Scientists have found evidence to prove that a tsunami in the past affected the area where the metropolis of Manila is now located. Movement of the Manila trench could trigger the formation of a tsunami.

Based on scientists’ tsunami prediction models, the time between the formation of a tsunami and the impact on the coastal region of Manila and the surrounding area would be only nine minutes. The waves could reach 16 metres in height. Consequently, it is important to put an effective prevention program in place for a future natural disaster of this kind.

Manila is in an area that is at high risk of typhoons. Indeed, approximately 20 typhoons per year affect the Philippines, and a significant number affect Manila^[13]. They cause damage due to wind, rain and the floods that can follow. It is important that this risk be assessed in construction projects as well as in the city’s planning and development.

According to the Intergovernmental Panel on Climate Change (IPCC), the wind speed and the number of category 4 and 5 cyclones are expected to increase in the next few years due to global warming. This will make Manila even more vulnerable to typhoons.

Manila experiences two types of floods: coastal floods (high risk) and urban floods (moderate risk).

Coastal Floods

Coastal floods occur, as the name suggests, along the coast. In Manila, this occurs along the coastline of Manila Bay, which is connected to the South China Sea.

Coastal floods have a number of different causes, primarily:

• waves

• tides

• storms, such as typhoons

• variations in sea level

In Manila, coastal floods are mostly related to tropical storms and typhoons. In the longer term, the capital is threatened by rising sea levels due to climate change.

Urban Floods

Urban floods have a number of different causes, such as heavy rainfall due to monsoons. They also result from some of the same causes as coastal floods. What is characteristic of this type of flood is that the water cannot easily run off because much of the urban surface is impermeable. This makes it difficult to drain the water, which ends up accumulating in the city.

In Manila, the monsoon is a major cause of urban floods. During this rainy season, a lot of precipitation falls on the metropolis over a short period, leaving no time for the water to run off.

Landslides are a natural disaster. However, in Manila, and more generally in the Philippines, landslides are often a consequence of another natural disaster. Here are a few examples.

• In August 2012, the monsoon rains caused landslides, including one in a slum north of Manila^[17]

• In December 2017, Tropical Storm Kai-Tak caused several landslides, killing more than 20 people^[18]

• In July 2022, a 7.1 magnitude earthquake caused more than a dozen landslides^[19]

The metropolis of Manila is particularly vulnerable to natural disasters. As mentioned above, because it faces many natural hazards, it must be prepared to deal with all of them.

In general, the city of Manila and the Philippines have good disaster management protocols and are ready to deal with various environmental risks.

Natural disasters follow one after the other, making it difficult for the country and its cities to recover from these events.

The Philippine government is the main actor in preventing natural hazards from becoming disasters. However, the government lacks financial resources to do so.

Manila, and the Philippines more generally, are not very prepared to deal with natural disasters. The chain of natural disasters and the lack of money make it difficult to put adequate prevention plans and measures in place.

This problem has two major consequences:

• Extensive material damage

• Difficulty protecting vulnerable people

Extensive Material Damage

The first consequence of a natural disaster is that there is extensive material damage because the authorities do not have the money and sometimes do not have enough time between natural disasters to fully rebuild and reinforce the infrastructure.

In the Philippines, from 2000 and 2012, natural disasters cost an average of $252 million per year^[21]. The agricultural sector requires the most money, followed by infrastructure. Most of the natural disasters that affect the country cause enormous damage to fields, houses, infrastructure such as roads and aqueducts, as well as sewer and electricity systems.

Sometimes a lack of financial resources is not the problem, but rather how they are managed and distributed.

This was the case in 2022 after Tropical Storm Nalgae. The National Disaster Risk Reduction and Management Council recommended declaring a state of disaster. However, the country's president, after consultations with the Department of the Environment and Natural Resources, decided against this. The Department considered the damage to be too localized.

Declaring a state of disaster in a region makes it possible to free up funds for this type of situation and to freeze the price of goods.

More than 2 million people were affected by the storm and the material damage to infrastructure was evaluated at more than $18 million. The damage to the agricultural sector was evaluated at more than $9 million and the damage to housing was close to $300 000.^[24]

The Difficulty in Protecting Vulnerable Populations

The second consequence is that the populations most vulnerable to natural disasters remain in situations of extreme precarity when there are insufficient resources and plans in place to help them.

Poor populations often live in slums, sometimes even when this is prohibited by the government. These places are often unsafe and dangerous, and the houses are often flimsy, which increases the risks to these populations in the face of natural hazards.

The government does not have the means to relocate these populations to safer areas, or to inform people of the risk and prevention measures to take in the event of a disaster.

The high frequency of natural disasters makes it even more difficult for the most disadvantaged populations to escape poverty.

Since the country lacks the resources needed to help disaster victims and to repair the infrastructure and adapt it for future natural disasters, the country must rely on humanitarian aid. This aid comes from international organizations and various countries.

This aid comes in the form of:

• financial aid

• support in preparing emergency and prevention plans

• support on the ground after a natural disaster (providing medical care and essential goods)

To access the rest of the unit, you can consult the following concept sheets.