9.4 Sustainable management in hazardous environments Flashcards
Tectonic hazards in the Philippines
Tectonic – Volcanoes
Highly vulnerable to tectonic hazards as it lies on an active and complex tectonic area; the Philippines mobile belt on the Pacific Ring of Fire. Subduction is occurring (e.g. the dense oceanic Philippines plate is being subducted beneath the continental Eurasian plate) resulting in wet partial melting and the explosive and violent eruptions of andesitic magma leading to earthquakes and volcanoes with high VEI. There are 53 volcanoes (18 active) South China Sea Plate (part of Eurasian Plate) subducts under the Philippines plate. Stratovolcanoes formed eg Mount Pinatubo which erupted in 1991, Mount Mayon in 2009 and Taal in 2020. With andesitic, viscous lava, these volcanoes are explosive with VEIs of 3-6 leading to explosive eruptions that are Plinian in style – consist of composite hazards gas/lava, pyroclastic flows which increases the difficulty in managing them These volcanoes are cone shaped with steep sides – made up of layers of ash and lava deposits which creates the further risk of mass movements (mud flows known as lahars) which are triggered when unconsolidated ash deposits are remobilised by heavy rainfall. These secondary hazards can recur for years after an eruption remobilised with recurring monsoon rains and typhoons eg Mt Pinatubo lahars recurred for 6 years through 4 rainy seasons with annual rainfall of 4000mm moving half the erupted material from the slopes of Mt Pinatubo as mudflows.
Tectonic –Earthquakes
Collision of Sunda, Eurasian and Philippines plates. 7.1 Mg Bohol Earthquake 2013, shallow focus 20km – reverse fault caused by compression rather than subduction at an unknown fault system Bohol island – population of 1.2 million – densely populated which increases the vulnerability of a population.
Atmospheric hazards in the Philipines
Atmospheric – Tropical Cyclones (Typhoons) Located in the Pacific Typhoon Track at 5-25⁰N latitude with sea temperatures above 26⁰C, allowing warm, moist air to rise rapidly. This location is within the ITCZ associated with low pressure and unstable air as the NE and SE trade winds meet. The latitude also allows for sufficient spin from Coriolis effect to allow typhoons to develop and cross the country anywhere from East to West driven by easterly trade winds. There are 20 typhoons a year – 8/9 make landfall – super events like Typhoon Haiyan (Yolanda) are responsible for the last 6 mega events and are possibly on the increase as climate warms and sea levels rise, increasing incidence/intensity of typhoons and impacts of flooding. Typhoon frequency is a problem: As there are so many typhoons, the capacity to cope reduces over the typhoon season as ground becomes saturated so flood risk increases and people are already living in temporary evacuation shelters. Sometimes two typhoons may approach and circle one another leading to grave effects – known as the Fujiwara Effect The physical geography of the Philippines (>7,000 islands created as a result of subduction of plates to create island arcs) increase vulnerability to this risk, especially in relation to flooding associated storm surges. Also means that due to the high terrain and steep relief, people live in vulnerable areas at the coastline where the typhoons make landfall and have their most impact before energy is dissipated. These especially affect the densely populated island of Luzon. Anthropogenic climate change is arguably making this worse.
Poverty + lack of development affecting Philippines ability to cope with hazards
GDP per capita $ 3498 (World Bank, 2022) HDI 0.699 (UN) Relatively poor country so pressure on government funds for basic amenities and poverty alleviation which the govt has to balance against what it spends on disaster planning, prediction and resistant infrastructure with basic services. The cost/benefit analysis of any hazard management is an important consideration. Often has had to rely on international aid in the aftermath of a disaster and the recovery from hazardous events has been prioritised over investing in the reduction of impacts from future episodes Only 0.75% of the Philippines’ national budget is allocated to disaster prevention and relief. Large-scale and recurrent disasters have had long-term implications on the country’s economy: · Since 1990, 565 disaster events have caused an estimated $ 23 billion in damages · Approximately 85% of the sources of the country’s production have been reported to be susceptible to disasters · 50% of the total land area is considered to be economically at risk At the household level, there is little access to insurance and poverty is one the most important factors determining vulnerability and there is little scope to get out of the poverty trap… 20% of its residents live below poverty line, there is significant economic inequality, and over 40% of Filippinos are thought to work in the informal sector. ·Cycle of poverty and vulnerability -children regularly lose school days due to disasters and suffer the compounding negative effects on their schooling during disasters; schools are often used as evacuation centres, buildings are damaged, teaching materials are lost or damaged, schedules are disrupted and returning to schooling might be impossible for children from low-income backgrounds. This has even longer-term cascading impacts Landlessness also compounds the problem putting more people at risk of hazards. Many people migrate from rural areas to cities like Manila in search of work as they have no security. Large scale migration leads to people living in marginal areas eg steep slopes in squatter settlements, close to rivers which are more susceptible to risk of mass movements and flooding.
10% of the population live in slum dwellings and in Manila alone, there are 400 slum colonies which are susceptible to flooding during monsoons and typhoons. Elsewhere, indigenous people are forced onto steep slopes as lower land is farmed commercially for rice – as they deforest and farm these, they are at risk from heavy rain brought by typhoons which increases the lahar risk (mass movement).
Population affecting Philippines ability to cope with hazards
Risen from 19 million in 1950 to almost 114 million (2021) Increased deaths are inevitable as an increasing number of people live in vulnerable areas Some areas are especially more vulnerable eg Island of Luzon
Luzon: Largest island and most populous – has one of the highest pop densities in the world increasing vulnerability
Population attracted to mineral wealth (gold, asbestos, chrome and copper) and volcanic fertile soils making commercial agriculture and exports of rice, cotton, tobacco, corn and sugar possible as well as the capital city, Manilla. However, the island’s eastern side is parallel with the subduction zone and Philippine Trench making this an active seismic zone with the two most active volcanoes of Mt Mayon and Mt Pinatubo NW of Manila located here. Along with two mountain chains and rivers, this makes this area especially hazardous to not just volcanic eruptions but flooding and mass movements associated with tectonic activity and heavy typhoon rainfall
Economic growth affecting Philippines ability to cope with hazards
Much of the country’s exports and trade income have relied on resource-extractive industry which further create implications in terms of disaster vulnerability and sustainable economic growth. Industrial development has threatened natural protective shields, including mangroves, watersheds have been urbanised, forest cover removed, and mining has destabilised slopes. 50% of mangroves have been cleared as a result of rampant conversion of natural space to the use of agriculture, fish ponds, aquaculture – all to generate export income. Mangrove ecosystems are one of the best buffers against typhoons, coastal flooding and storm surges, thereby increasing vulnerability and risk in coastal areas Also, the forests have been degrading due to extensive use of mangrove for timber and fuel, and due to the expansion of coastal settlements. Tropical rainforest has also been cleared almost entirely for export income – this was a barrier to landslides and mudflows Large scale mining development has been found to be another source of environmental degradation and increases the threat of mass movements
Sustainable hazard management Philippines overview
Poverty alleviation is now a key part of the disaster risk reduction and management plan in the Philippines, based upon the view that reducing poverty increases capacity to cope and reduces vulnerability to the impacts of natural hazards. World Bank gave $250million loan to support recovery and reconstruction and poverty alleviation eg better housing, better risk mitigation.
With greater risk perception at government level, more money is now being allocated to preparation, rather than response, which is arguably a more sustainable approach. Moreover, at the sub-national levels, 5% of budgets are now spent on disaster management.
However, in this multiple hazardous country with dense populations experiencing a high degree of inequality and who are set within the context of a country who’s population and economy has been growing quickly, sustainable management of hazards is challenging, especially finding the money to prepare for hazards rather than merely react to, and recover from them, especially as so many people and so much economic activity are located in such vulnerable areas.
It may be argued that the success of sustainable hazard management depends on hazard type and has arguably been better with some hazards, notably volcanic than it is with atmospheric typhoons. However, this still depends on risk perception amongst different groups which is strongly influenced by past experience and the degree of risk they are prepared to take in order to make a living.
Evidence of sustainable managment of tectonic hazards Philippines
National Disaster Risk Reduction and Management Plan 2011-2028 aimed to reduce disaster risk in numerous ways and has arguably been most successful in sustainably managing seismic hazards, notably volcanic At the national level, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) manages earthquakes, volcanoes and tsunamis Since 2015 the country has 74 seismic stations for earthquake monitoring 36 tsunami detection stations 6 volcano observatories
10 tsunami early warning systems monitors active volcanoes looking for various signs of eruption (e.g. seismic tremors; steaming; ground swells; localised landslides) and produces various alert signals for each volcano based on past history. National Lahar Mapping Programme: maps distribution of lahar deposits from past explosive eruption. Aim is to generate lahar identify possible evacuation routes Furthermore, there are hazard maps of susceptibility to landslides and liquefaction There has been education to ensure that all stakeholders are adequately informed and know how to react to events – e.g. PHIVOLCS produces a volcano preparedness document, an earthquake preparedness document, 6 newsletters a year and tsunami comics. Preparedness is also enforced through special events like civil defense day, fire prevention month, disaster consciousness week Early warning systems are further enhanced by the Free Mobile Disaster Alert Act of 2014, which mandates telecommunication operators to issue free public warnings via mobile phones, as required by the state, PHIVOLC or PAGASA
Examples of successful forecasting, prediction and mapping in the Philippines
- Mt Pinatubo volcano 1991 early prediction and warning system which accurately predicted the eruption. Alerts were issued and a hazard zonation map was circulated one month before – Over 200,000 people safely evacuated. Especially impressive and a relatively small loss of life for this biggest eruption of the 20th century considering the volcano had been dormant for 500 years and the eruption covered radius of 100km with 1 million people living within 30km of the volcano on Luzon Island. Only 847 people died , 300 by ash laden roofs collapsing , 100 by lahars and rest from disease due to poor sanitation in evacuation camps.
- Furthermore, eruption of Mount Mayon in 2009 saw PHIVOLCS progressively increase the alert level to level 4 and which led to the successful evacuation of 9,000 families in an 8km exclusion zone. This reduced the impact of the event by ensuring that there were only 5 deaths relating to the eruption.
Evaluation of sustainable management of tectonic hazards Philippines
However, not all tectonic hazards have been as successfully managed and success also varies spatially and within the population. Furthermore, the long term impacts of even well predicted volcanoes have often been less sustainable. Like anywhere in the world, managing earthquakes has been less successful even with increased govt perception and the establishment of PHIVOLCS, arguably this is due to the lack of precursor activity associated with volcanoes. EG Bohol Earthquake 2013 went unpredicted causing 222 deaths and damage to 73,000 structures in a M7.2 earthquake. This demonstrated the shortcomings of a newly established and young PHIVOLCS institute since seismologists at PHIVOLCS had not even known about the fault line transecting Bohol Island.
Moreover, even when accurately predicted and warnings and evacuation orders are issued, the economic and long term impacts of volcanic eruptions are less successfully managed and with such high economic losses in a relatively poor country, this limits future spending on prediction and sustainable hazard management. EG whilst Mt Pinatubo was accurately predicted and there were only 847 deaths, over 1 million people lost their homes and the cost of the eruption was $700 million with the 1991 harvest destroyed thereby inflating food prices and key infrastructure like roads and bridges buried under the ash. Moreover, the long term effects have been significant and under-estimated– eg lahars recurred for 6 years through 4 rainy seasons in the Zambales mountains to the west of Pinatubo – they emerged every year as a mudflow when the monsoon rains/typhoons arrived and remobilised ash deposits which buried lowlands with 3km³ of ash making a further 200,000 people homeless. Farmland wasn’t useable for many years, severely impacting exports and the economy and so reducing income available to the government for future hazard management whilst individuals were left with no assets or home without compensation from non-existent insurance policies Elsewhere in the Philippines, the Taal Volcano 2020 shows conflicting demands of economic prosperity and the ability to create a sustainable livelihoods for a poor and growing population and managing one of the world’s deadliest volcanoes which is only 60km south of Manila on an island in Lake Taal. In an attempt to manage the volcanic risk, permanent settlement on the island is prohibited by the PHIVOLCS, who have declared the whole Volcano Island as a high-risk area and a Permanent Danger Zone Despite the warnings, some families remain settled on the island, earning a living by fishing, mining scoria (pyroclastic deposit) and farming crops in the rich volcanic soil.
In fact, the population here is growing rapidly at 9.6% per annum (3 times national average) increasing the vulnerability as more people are at risk. Despite their prosperity, the island could not cope with a major eruption – there are only 215 boats which could transport only 2000 people so only half of the population could be evacuated in 2020 eruption where 39 people died despite 24 hr monitoring and warnings issued. Ironically, the Philippine Institute of Volcanology established here has lowered the locals’ perception of risk reducing their preparation for the hazard, making them more vulnerable despite the improvements in hazard management. Similar constraints to sustainable management associated with lower perceptions of risk were seen with indigenous tribes people (Aeta) tribe who lived on the flanks of Mt Pinatubo. It is estimated these totalled 50,000 people at one time. Whilst many evacuated some with a more fatalistic view of the hazard, refused to evacuate and hid in caves on the volcano. Unfortunately, they were killed by pyroclastic flows and buried under ash. This group has been significantly affected by the eruption as they were displaced from their homes. Resettlement programmes were put in place, far from their cultural homeland but many have returned to the lower flanks of the volcano but there has been significant dilution of their cultures notably in terms of language and especially in competition for scarce land.
Evidence of sustainable atmospheric hazard management Philippines
At the National Level: Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) – established since 1972 but after disastrous flooding, typhoon and landslide deaths in 2011, have become more focused on minimising the impacts of hazards such as making any new cutting down of forests illegal. The Philippines has also devoted considerable resource to the construction and provision of disaster reduction facilities such as river dikes and sea walls, as well as non-structural measures like warning systems for typhoons, floods. Flood control projects and watershed management projects, in additions to the broader reforestation effort, are all geared to mitigate the worst effects to flooding caused by the heavy rainfall and storm surges associated with typhoons. Successful prediction of Super Typhoon Haiyan 2013 PAGASA identified the emergence of typhoon Haiyan days before it made landfall in the Philippines in 2013 and its path, rainfall, flooding, landslides and storm surges was predicted quite well. The highest alert level was issued for provinces along the path of the typhoon so many people were aware of the potential risks to life and property
Sustainable atmospheric hazard management Philippines evaluation
However, despite improvements in successfully predicting atmospheric hazards, communicating and disseminating warnings has limited the success of the new technology. This is especially hindered by low perception of risk held by the huge number of vulnerable people who live within 60km of the coastline who are trying to make a living in this zone without any form of insurance against the hazards they face. EG despite successfully predicting typhoon Haiyan, PAGASA did not convey the seriousness of the storm surge and did not manage to reduce the impact of Category 5 Typhoon Haiyan in 2013. The result was huge social and economic losses: 6,300 deaths, $9.6bn losses, the brunt of it affecting the agricultural sector with 20% losses amongst fishing sector, an estimated loss of 260,000 tonnes of rice, leading to severe food shortages across the country with approximately 2,5 million people requiring food assistance. Furthermore, it was estimated that the event drove nearly one million people into poverty. In the longer term, overall economic production fell which reduced the GDP by 0.9% due partly to damage to electricity infrastructure and disrupted electricity production affecting the output of industry, manufacturing and services . Whilst volcanoes and earthquakes have been relatively low in frequency with relatively episodic impacts, the frequency of tropical cylones affecting the Philippines severely affects the government’s ability to sustainably manage this hazard. With 20 typhoons affecting the Philippines each year and 8/9 making landfall, these hazards cause the most disaster damage and of all the disasters, cyclones and their accompanying landslides, storm surges and floods have caused the largest losses of life and property mostly because the majority of the population is living within 60km from the coast. Super Typhon Haiyan goes to show the limitations of sustainably managing tropical cyclones. It is estimated that the Typhoon Season costs approximately 2% of the country’s yearly GDP on average, and another 2% is consumed by the recovery activities – this creates a recurrent disaster trap which hinders overall economic development and results in the Philippines lagging behind neighbours like Thailand, Vietnam and Indonesia. The frequency of these disasters has been considered as a major obstacle to sustained, long-term economic growth and limits the ability to sustainably manage this hazard. Moreover, this may be set to get even worse in the future as climate change warms ocean waters and the intensity, even if not the frequency of tropical cyclones is set to increase - 80% of all the damages and deaths caused by typhoons between 1970-2014 have been caused by 6 super-scale events
