Zhouqu County Mudslides

On the 8th August 2010, a mudslide occured in Zhouqu county, in southern Gansu province (Gannan Tibetan Autonomous Prefecture) in the PRC. The mudslide was 5km long and 300m wide, and up to 5m thick in places.

Causes

The mudslide was caused by a variety of factors, human and physical.

Forests around Zhouqu had been cut down for mining and agriculture which lead to soil erosion and destabilisation of the slopes, as roots were no longer holding the soil together and trees could no longer absorb water from the soil, leading to faster soil water saturation.  Despite the logging ban in 1998, trees continued to be felled. In the PRC, there had been 53 hydroelectric construction projects in recent years, with 12 just within Gansu province, where Zhouqu county is located. The dams have caused 750,000 tonnes of water and soil erosion and over 3 million cubic tonnes of bulldozed material, throughout the country. This has left the slopes weak and exposed to rainfall, allowing slides to occur more readily.

Oscillations between the patterns of El Nino and La Nina (climatic events where air currents across the Pacific Ocean change, effecting the local weather systems among dozens of countries) caused unusually intense monsoon rains in 2010.  Regions were receiving an extra 24 mm of rain above the normal daily rainfall. In ‘the largest downpour for a century’ 96 mm of rain fell in just one hour in the area.  The earthquake in Sichuan two years previously created cracks in the rock face and destabilised the ground; Zhouqu county is very close to Sichaun province, so instabilities within Sichaun can very easily effect towns within Gansu, directly to the North. The 9-month drought which preceded the heavy rain had added to the weakness and instability of the soil, especially when followed by the heavy rainfall.

Impacts

Social Impacts:

  • 1,471 people died due to the slide.
  • 1,200 people had to be rescued from the debris.
  • 300 people were never found, and are presumed dead.
  • 1,700 people who were evacuated from the immediate area were forced to live in schools. In total 45,000 people in Zhouqu county were evacuated.
  • Medical care in the region was disrupted as 10 doctors from the Zhouqu People’s Hospital were among the missing.

Economic Impacts:

  • 66% of the county went without power, disrupting local businesses and transport.
  • More than $40 billion worth of damage was caused in Gansu.
  • Power lines were down in 2/3 of the county which had to be repaired. Wider infrastructure was destroyed at great cost.
  • Mudslides throughout China in 2010 destroyed 8.76 million hectares of crops to be destroyed.
  •  The livelihoods of millions of people were entirely destroyed or otherwise decimated and China’s capacity to export was massively reduced.

Environmental Impacts:

  • 300 buildings were buried under mud.
  • A 3km temporary lake formed behind a blockage when the mudslide reached the local river at the base of the city of Zhouqu where the slide occured. This dam later burst causing further damage.
  • The river was clogged with debris, damaging habitats and reducing biodiversity.

Management 

  • 7,000 soldiers, firefighters and medical staff were deployed by the government. 20 speed boats and 4 helicopters were also mobilised.
  • Gansu province received 120 million yuan ($17.7 million) by August 13th 2010.
  • The PRC government promised local families $1,182 worth of financial aid for each victim lost.
  • Tents, food and medical supplies were rushed to the stricken area but the remote mountainous location made access difficult.
  • The governmentpromised to help rebuild homes and buildings in the affected area.
  • A National Day of mourning was observed to help with the emotional trauma.
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Sri Lanka Mudslides, 2016

Image result for sri lanka mudslide 2016

Mudslides hit Sri Lanka in May this year. Mudslides hit three villages in central Kegalle district. The landslide started near the town of Aranayake on the 17th May, 2016, but events leading up to it should have made the outcome predictable from the 15th onward.

Many cities were flooded with more than 100mm of rain on the 15th of May. International airports had to be closed just from the weather, and 35 families had been displaced. Airports would remain closed over the next few days.

Causes

3 days of torrential rain destabilised slope areas, in the heaviest rainfall in 25 years. The rain started on the 14th May.

Before the extreme weather, Sri Lanka had been experiencing a drought, and power cuts as hydroelectric power stations could not function. A rare benefit of the extreme weather which triggered the event was that the dams filled up to 75% capacity, allowing a supply of electricity to rescue workers to help them work effectively.

The main landslide area was very sparsely populated by only a few minor villages. No major work had been undergone on the slopes, as evidenced by footage of the event. Instead it was caused by a sudden huge increase in slope water content combined with susceptible rock type.

Impacts

On the 18th, 134 people remained unaccounted for, and 14 bodies had been recovered, with 37 deaths total. 350,000 people were displaced. 92 deaths have now been confirmed. 220 famlies were reported missing according to the Sri Lankan Red Cross. As of May 25th, the death toll was deemed to be 101 with 100 missing people.

The slide crashed into 3 separate villages; Elangapitiya, Pallebage and Siripura, all of which were obliterated.

60 houses were buried in dirt.

The mud level was up to 30ft deep in some areas.

Many sectors of infrastructure were effected, such as planes. Many major roads were entirely flooded, including the Southern Expressway. There were heavy power failures in some towns. The government warned members of industries such as fishing to not go to work until the situation was sorted- this was of course an attempt to save lives, but there was an economic impact because of this upon fishermen.

Response

The Meteorology Department of the government issued a severe weather warning on the 14th, for 12 hours. 100mm of rainfall was expected, with wind speeds of up to 80kmh in exposed areas.

One of the initial responses to the initial weather, was closing down air traffic.  Closed airports included: Bandaranaike International Airport (flights diverted to Cochin International Airport or Mattala Rajapaksa International Airport), and Ratmalana Airport. The Sri Lanka Airforce had to be called in to rescue stranded fishermen. The Navy had to save 200 people trapped in floods on the 17th, and the mud slides started, killing 21 in just one slide. The Airforce continued rescue work throughout using military grade helicopters. 81 Navy flood relief teams were dispatched.

Rescue teams were sent out to the area specifically, so that 156 people had been rescued by the 18th May, along with 1,550 people already sheltered in seven different evacuation sites. Soldiers were active in rescue efforts for weeks afterwards. Military spokesman Brigadier Jayanath Jayaweera said that the situation was being constantly assesed and that more troops would be deployed as needed, but that he doubted they would find many survivors.

More than 185,000 people who lost their homes were housed in temporary emergency shelters. The rain hindered the effectiveness of rescue efforts, in addition to causing the initial event. Many roads were underwater, and impassible, and national parks were completely closed off, and rescuers struggled to bring in their equipment. The Ceylon Electricity Board imposed emergency power cuts as a precautionary measure. In one night, the Army and Navy evacuated 26,000 people from Colombo (the capital). 1,500 armed personal were rallied,  including 71 officers.

All schools were closed on the 20th.

International efforts from other countries included:

  • Australia contributing $500,000 to UNICEF for humanitarian assistance
  • India pledging to provide assistance, and then bringing in Navy ships full of supplies.
  • Japan sent planes carrying emergency items, such as generators, blankets, and water purifiers.
  • Nepal offered $100,000
  • Pakistan gave a 30-bed field hospital
  • Singapore Red Cross donated $150,000 in relief items
  • United Nations- in collaboration with other NGOs- offered people to help administer aid
  • USofA provided $50,000 in immediate aid and a further $1 million in providing water for populations vulnerable to floods.

(Image Source: http://www.bbc.co.uk/news/world-asia-36328863)

Campania Mudslides, Italy – 1998

On the 5th May 1998, a mudslide hit Campania in Southern Italy.

The region was very hard hit by the area, and many individual towns were at high risk; Sarno and Quindici being two of the most effected. The area has the highest mudslide rate in Italy, with more than 631 since 1918. One such earthquake was in 1980, when nearly 3,000 people in Campania were killed in a single event. 65% of Italy in deemed at risk from landslides.

There were at least 17 slides during the event.

Causes

”Everything is to blame — It’s nature, it’s the authorities, and it’s also us, the citizens”–  Francesco Fligente, a local bus driver. ‘The mountain has been burned systematically” –Andrea Giordani, land surveyor. “[The mudslide was] not a natural calamity but a disaster caused by decades of ransacking the land and sprawling construction.” – WWF

The town had been hit by torrential rains beforehand, which remained ongoing during rescue attempts. The area is made of sedimentary rocks, which are predicted to eventually crumble into the nearby Tyrrheanian Sea, as the soil is very fragile and prone to erosion. This was not helped by local deforestation and a habit of burning patches of ground to achieve this, or by structural work that weakened slope integrity further. Removal of chestnut trees has an especially large effect, as these trees’ large root systems hold soil very firmly together.

The government received criticism for not declaring a state of emergency in the region on the 3rd, and not giving evacuation notice, when geologists first came to believe that slides were about to occur.

Campania is a centre for illegal housing projects, with 20% of Italy’s illegal construction, according to environmental watchdogs. Farmers regularly burned down local plantlife to make room for crops and livestock. Environmental law was regularly not enforced, or even just entirely ignored. Regional officials blamed central government for not giving enough funding to properly maintain the laws.  Meanwhile, the central government blamed the Mafia for the apathy towards environmental laws, and that they were benefiting from the poor regulations.

Geologists were regularly warning about the dangers of building while ignoring regulations in a risk prone zone.

Many homes in the area were built in very land-slide-prone sites, or too close to rivers. 24% of the area is deemed “at risk” land.

Many of the demolished buildings were poorly built out of concrete, and did not have proper foundations.

Impacts

The first news of the start of the event was the Sarno mayor calling up Civil Protection Authorities asking for help to cope with a torrent of debris approaching the city.

At least 147 people died, with about 100 of them from  just the town of Sarno. 1,000 people were left homeless. More than a dozen of the deaths were children. About 5,000 people lived in Sarno. Mud deposits were up to 13 feet deep. The Sarno hospital- Villa Marta- was entirely decimated, with 6 members of hospital staff killed. Workers carried 60 patients outside, and had they not, many more would have died; building of a new hospital outside the worst risk zone had been planned, but government budgeting to allow EU entry slowed this down- the unfinished new hospital was completely undamaged.

A whole public school was also destroyed, trapping many teachers and pupils inside. Many other buildings were also destroyed. Rivers became clogged up with mud up to 2m deep, and 1,5000 people lost all their posessions.

Whole swaths of greenery on the mountain slopes were flattened.

The  most effeceted towns were: Irpine, Salernitano, Sarno, Quindici. Episcopio, Taurano and Bracigliano, but over 230 were impacted.

The most dangerous areas were inhabited by the poorest civilians, who are the most hard hit, as they cannot pay effectively for future accomodation or relocation.

Response

Rescuers from Civil Protection arrived only a few hours after the initial plea was given, at night time. This timing hindered rescue work, as it was too dark to start any serious rescue work and helicopters to help would be unsafe to pilot. The government vastly underestimated the event’s scale, too, and initially only sent a few earth-moving vehicles, that became stuck themselves. By the 6th, volunteers had resorted to digging with their bare hands.

A funeral was held on the 11th May 1998 for the dead in a football field locally, with rescue workers contributing to the ceremony.

Prime Minister Romano Prodi pledged $30 million in relief and reconstruction on the Friday, 4 days after the event.Previous aid efforts had been largely cut down from what was pledged however, due to concerns that over spending would prevent their entry into the European Union. The government even cut funding to the Centre of Geological Studies, so that thousands of geology graduates and scientists were unemployed.

President Scalfaro said that they should focus on reconstruction and aid efforts before trying to find a guilty party. International trips by government officials were cut short in order to stand with the Italian populus and help organise repairations.

4,000 firefighters, troops, forest rangers and medical workers including 80 US marines based in Naples aided the rescues. 5 schools were converted into emergency shelters. Just one of these schools, Edmonde de Amiciis Elementary School housed 260 survivors.

Philippines mudslide 2006

On 17th February 2006, a mudslide hit the village of Guinsagon in southern Leyte province in the Philippines. The slide covered 9km^2, was 3km wide and in places 30m thick. Half a mountain collapsed on the single village. .

Causes

The main cause of the mudslide was a La Ninya event in the Western Pacific. 200cm of rainfall fell in 10 days, weakening the slope strength. Slopes in the region are mostly very steep and mass movement and mudslides occur frequently.

Widespread deforestation during the past 70 years have also increased slope instability. The slide was ultimately triggered by a small local earthquake of magnitude 2.6Mw.

Exposure in that area of the Philippines is high. In 1991, 5,000 people were killed when typhoons triggered landslides, and a similar event in 2003 killed 133 people. Mudslides and landslides are a constant threat due to:

  • heavy and prolonged rainfall from typhoons
  • Steep hillsides largely built of weathered volcanic rock
  • Extensive faulting and earthquake activity

Many villages are located at the base of steep slopes in the direct path of mudslides, and rural populations are high. The people are very poor and have high population growth. Southern Leyte is one of the poorest areas of the Philippines. Between 1995 and 2000 the population grew by +2.73%, placing pressure on environmental resources.

Logging bans have not been enforced by the government, largely due to political corruption. Even where sustainable logging has been practiced, in many places trees with shallow roots have replaced trees with deep roots, and thus made the slopes far less stable.

Impacts

Survivors described how a “wall of mud” descended on the village, killing over 1,000 people, including 246 children at a primary school. Almost every one of the 300 homes was destroyed. The slide killed thousands of livestock and buried the farmland; around 16,000 people were affected.

Response

Hazard mitigation maps have been made of Southern Leyte, but are not very detailed, so that villages that will be effected by mudslides cannot be identified. Following heavy rains and the deaths of 20 people in a nearby village, warnings were issued between the 4th and 17th of February, and several hillside villages were evacuated. However, many people chose not to leave.

Evacuation centres were set up around St Bernard, the capital of the region. Emergency aid in these centres provided safe drinking water, sanitation and health services. The region is very poor, however, so they cannot afford communications, which slowed down response times. Two hundred rescue workers were brought into the site. Unlike earthquakes, mass movements have few survivors.

International aid was provided by the Red Cross and Red Cresent, and their appeal raised US$1.6 million.

The government has commissioned a US$1.5 million geohazards survey and mapping of Leyte to try to prevent future similar disasters.

BRV Debris Flows 1999

In December 1999 Vargas province in  the Bolivarian Republic of Venezuela was by many debris flows, made of sand, gravel, boulders and trees, with a consistency similar to concrete.

Boulders up  5m diameter were transported down to the coast. 2 million^3 of debris appeared in coastal alluvial fans, which extended of the coast by up  250m into what previously the sea.

Causes

Between the 8th to the 19th of December 1999, a cold front across the BRV deposited 914mm of rain on mountainous coastal regions. In that area, the Cordillera de la Costa runs alongside the coastline. The highest is just 10km away  from shoreline. The seaward slopes thus very steep. Runoff of water is very rapid and the steams high energy because of this.

The mountains themselves heavily weathered. They covered in clay, which very weathered away. The clay feeds of sedimentation downstream.

Widespread deforestation has reduced numbers of trees hugely. Roots are less able to fulfil purposes; therefore interception is reduced, and an even greater addition of slope instability.

Because the mountains drop suddenly, there is not much free available for settlement, and alluvial have become popular for settlement. A 6.3% population increase between 1990 and 2001 gas concentrated urban development closely. These coastal developments hit hardest by debris . The fans themselves are caused by continuous flooding events, so a disaster  bound to at some point.

Impacts

Estimates of death toll range  15,000 to 30,000 deaths. 214,000 people effected. 44,000 people refugees.

20,000 homes destroyed with a further 40,000 damaged. Many single storey homes entirely buried. Towns in Carmen de Uria were even swept away.

Hazard mitigation

The people entirely unaware of the risk and thus there was no preparation in case such an event occurred. Flows can be somewhat predicted based on accumulation of sediment in mountain waters, as a debris cannot without sediment present.

Removal of slums on slopes should have been a priority. The president announced shortly afterwards that victims be re-settled away from the coast, but this was questionable as many  people  chose to live on the coast in order to avoid  the struggles of life in the interior of the country. Afterwards, 100,000 people whose homes had n destroyed were relocated to neighbouring  regions.

Many plains will not be suitable for human settlement in the future unless check dams can be built along rivers in  area. Flood channels have been constructed on the alluvial fans. Monitoring and early warning of exceptional rainfall runoff events had suggested, as have land controls in mountain catchment areas, and alignment of towns to match the path debris flows.

Volcanic Management in Montserrat

Montserrat belongs to the Lesser Antilles island chain; a series of volcanic islands formed by subduction of the North American plate beneath the Caribbean plate.

The island of Montserrat was formed by the Soufriere Hills volcano. The eruption stated in July 1995, and before 2005 had spewed out nearly 0.5km^3 of magma.

The potential hazard on Montserrat was fairly low- although the impacts on the population were huge, it was a small population, and they are still well equipped for evacuations if the situation becomes worse. However, the vulnerability was high due to the small area of the island available for people to move out to before any international evacuations could be planned.

Impacts

The main causes of hazards have been pyroclastic flows, tephra falls, debris avalanches and occasional lava flows.

In 1997, 19 people were killed when they returned to their homes in Plymouth, which they had been evacuated from previously.

The entire southern side of the island had a thick layer of ash on top of it, such that many of the plants were entirely covered.

Many people emigrated from the island after the initial evacuation. Many of these people permanently moved to the UK, the USA or other nearby islands. The initial population was 10,728 in 1990, which had decreased down to just 6,409  people in 2000.

Outmigration had a huge impact on the country. The loss of people meant there was a lack of workers, and thus many businesses suffered huge losses. The lack of customers had a similar effect. The sense of community was lost and many were disheartened at the loss of old friends or acquaintances. A disproportionate number of those who left were the more educated citizens, leaving a less skilled population behind.

The eruption itself crippled the economy. The ash destroyed much of the farmland. The destroyed land also reduced tourism hugely – and tourism was a huge factor in the economy, to which 40,000 visitors were drawn annually.

2/3 of the island is uninhabitable.

The roughly 6500 people living in the south lost everything but what they could pack in their rucksacks quickly.

Many who evacuated north had only low quality accommodation available. Often people would be packed into small rooms with bunk beds and people they had not met before, with 6 bedrooms in a house. There was frequently little or no sanitation, and no electricity or gas available.

Management

The people living in the southern half of the island were evacuated northwards. This plan backfired somewhat as half the population emigrated overseas that had been displaced.

The infrastructure is being rebuilt. A new airport has been completed.

The UK and EU have spent about £200 million on regeneration projects.

Since 1995, scientists have started carefully monitoring the volcano, and updating the public on any changes, and, where possible, warning people as to what impacts there were likely to be. Thanks to measurements of seismic activity, volcanic gases and ground deformation, they have warned people early of pyroclastic flows and allowed preparations so people could evacuate.

Haiti Earthquake- Causes of Vulnerability

The temperature had been 28 degrees celsius average, with 137cm of rainfall average each year. This climate means that soil is often damp and therefore prone to moving easily.

The Caribbean plate moved east while the North American plate moved west. A large movement in the north section of the Caribbean plate occurred, causing the earthquake. Rocks break when the tension is released, which is what then causes the damage.

The earthquake was shallow, and the plates hadn’t shifted for years. The plate boundary ran through the capital, Port au Prince.

The epicenter was very close to Port au Prince, while the focus was not far underground.

Haiti is the poorest country in the western hemisphere, so was ill equiped for this situation. Building quality was awful- and they lacked infrastructure. They had poor architecture, and many buildings were made of low quality concrete blocks.Roo

Roofs easily collapsed, trapping people underneath. Many houses were on slopes, causing slips.

Haiti Earthquake- Short Term Impacts

The earthquake happened on the 12th of June 2010.

  • 1/3 of the buildings collapsed it the capital.
  • 200,000 people died.
  • 1/4 of a million people injured.
  • 1.3 million homeless
  • 300,000 buildings collapsed
  • Water, communications and electricity networks were all damaged
  • Little food or water available.
  • A million people forced to sleep in the streets
  • Billions of dollars worth of damage caused

Haiti Earthquake – Long Term Impacts

Due to knowledge that future quakes are likely to occur, various measures have had to be put into places.

Earthquake simulations are run to see the panic which would occur in the real situation. People can practice organising emergency services for the situation. They are also to see how children react. Lots of screaming and running around.

The emergency services are being trained to act as best they can, by staying calm instead of running around, for instance.

The earthquake has had the greatest effect on the poor long term.

Even before the earthquake, there were large inequalities. The earthquake worsened this.

Half of the population was below the poverty line; after the earthquake, this rose to 80%.

Haiti Earthquake- Long Term Management

Building resilience and Future capacity

Some people have had to spend 3 years in their camps. They had:

  • No money to build

NGOs helped the local people by:

  • Improving financial support for rebuilding
  • Improving infrastructure
  • Training stonemasons to make future settlements stronger
  • Building new settlements on outskirts

The relocated people would have had to still pay rent for housing had the refugee camps not been set up; the camps helped provide shelter for those who would not have been able to afford this in their current financial situation.

In the refugee camps, people had to travel to work. Often the fees of transport were so expensive that people could spend more money travelling to and fro between work and the camps than they would earn. So, many people had taken to just sleeping rough outside their offices during the week and only coming home at weekends.

There were toilets in the camps so there was one between every five families. One of the main aims of the new buildings was to remove this issue.

  • Have to travel to work
  • Spaced out buildings
  • No heavy tiles
  • Use local technology so homes can be fixed by local people.
  • Buildings were built with plenty of open spaces, so people can get away from falling buildings more quickly.
  • Buildings have only a few storeys, so there’s less to collapse in during future quakes, and also have timber frames, which are more flexible, so less likely to collapse in a future earthquake.
  • Lightweight structures, and only using light weight tiles means that if anything collapses in the future, it will be less damaging to anybody around.

 

 

Creditors died with the earthquake

  • Businesses have to be reset up again
  • Oxfam helped with this:
  • Financial security to support many businesses
  • Monthly allowances

Most food was imported.

Oxfam was trialing different techniques in Haiti to get good crop growth. Oxfam funded small rice mills to get a better price at the market for farmers. Unprocessed rice is worth far less, so by allowing the rice mills to be more available, farmers can get more profits, allowing rural areas to support themselves better in the aftermath. With more rice mills, it is overall cheaper to use them.

Profits from mills help pay for drainage channels which increase yield again. This is an overall positive multiplier effect.

Land reform is a necessary feature of the rebuilding. Before the earthquake, unclear laws on land ownership meant that when the earthquake hit, camps had to be built in poor sites as the owners could not be tracked down and asked permission to use any land closer to the capital. Most of the land is only claimed by a few people, and overall this makes it hard to make long term investments. Companies and investors want a guaranteed pay out, which they can’t get from the unclear laws as it was.