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Multi-Hazard Case Study: Philippines - Coggle Diagram
Multi-Hazard Case Study: Philippines
Flooding
During the wet season, coastal floods can be caused by typhoon storm surges or rising ocean levels, and river flooding can be caused by heavy rainfall, even in areas subject to drought (where the soil is sundried and infiltration is significantly reduced).
✰e.g. the December 2010 floods in Eastern Philippines following heavy rainfall, which resulted in displacing 450,000 people in 19 provinces, killing 25.
Droughts
Drought can occur when the wet season (which is distinct in some areas e.g. Manila) hasn’t brought enough rain to last through the dry season, or when the dry season is particularly harsh.
✰e.g. Luzon Island drought of 2005, whereby a reduction in rainfall decreased river discharge, which decreased economic activity in the area due to a lack of hydroelectric power
Tsunamis
Submarine Earthquakes in any of the surrounding plate boundaries or fault lines can cause a tsunami local enough to be devastating to the Philippines
✰e.g. in 1976 a submarine earthquake of magnitude 7.9 caused a Tsunami of 45m high which hit the coastline of the Moro Gulf on the Southern Island of Mindanao, damaging 14 buildings in Zamboanga City.
Typhoons
The Philippines is situated in the latitudes between 520 degrees North of the Equator, so is vulnerable to Typhoons developing in the West of the Pacific Ocean, where Ocean surface temperature is above 26 degrees celsius, the Coriolis effect is strong enough to rotate the low pressure system, and trade winds will move storms Westwards towards the Philippines.
The Philippines experiences between 710 typhoons annually.
✰e.g.1 Typhoon Xangsane in 2006, which swept across Manila and the surrounding densely populated area, destroying homes with torrential rain and subsequent flooding/landslides
✰e.g.2 Typhoon Haiyan in November 2013, which had maximum oneminute wind speeds recorded at 315km/h before reaching land, the most powerful tropical cyclone to ever hit land, causing 6,500 human fatalities and affecting 11 million people.
Landslides
Landslides can be triggered by tectonic activity in the area from Earthquakes
Landslides can also be caused by heavy levels of rainfall which lead to cliff saturation if they fall in areas with a steep gradient.
✰e.g. 2006 Landslide on Leyte Island after 10 days of heavy rain, which buried a village and killed hundreds of people subsequently.
Earthquakes
The Philippine Plate and the Eurasian Plate can become locked together as the Philippine Plate is being subducted, which can cause the buildup and sudden release of pressure.
Earthquakes can also occur at Fault Lines in the area, where the plate has cracked under pressure.
✰e.g. 1990 Earthquake on Luzon Island, magnitude 7.8, killing 1500 people.
Volcanic Eruptions
The Philippines is near to a destructive plate boundary whereby the dense oceanic crust of the Philippine Plate is being subducted beneath the continental crust of the Eurasian Plate.
The islands were formed by a combination of folding at the boundary, and volcanos formed from magma that has risen to the surface from the Mantle below from the subducted Philippine plate.
✰ e.g. The eruption of Mount Pinatubo in June 1991, which killed 500 people, and caused crop failure due to the falling ash (from the eruption).