Local Scale Hazards Caracas

Question 1

Nature of the hazard

Answer 1

• Caracas is primarily situated in the base and on the flanks of a large valley making it very susceptible to landslides triggered by tropical storms of tectonic activity
• In 1999 tropical storms led to heavy rain. This triggered mudflow /landslides which killed over 10 000 people
• Situated on boundary of Caribbean and South American plates with faults running through the city and under the main airport.
• The large major earthquake was in 1967 (mag 6.5) and killed over 300 people
• Alluvial fans make up much of the basin’s floor. These are prone to liquefaction during earthquakes
• Slope angles regularly exceed 80% making landslides and runoff major hazards in the Caracas basin

Question 2

Social characteristics reflecting hazard impacts

Answer 2

• The safest and therefore most valuable land in Caracas is on the valley floor. Small landslides risk
• The wealthy live on the valley base with well-built expertly designed (westernised) buildings. Many have earthquake resistant technologies such as using triangular steel reinforcement of shock absorbing foundations
• The valley floor buildings are widely spaced to enable easy evacuation and to prevent and damage to one structure also impacting upon others.
• Residents of the Barrios have often adopted a fatalistic view of the hazards in Caracas. Deciding the rewards offered by the city are worth the risks of having to live on the hazardous valley sides in unreinforced masonry buildings.
• This clear division of the city shows the impact of hazards on its social/economic characteristics
• The water supply for Caracas shows no consideration of hazards or impacts. All 3 supply lines cross major faults which could be lost in a disaster
• The main road access to the Caracas valley between its airport an nearby sea port also crosses a fault as well as using a large bridge which is at risk of landslides. Again showing a lack of consideration for hazards within these characteristics

Question 3

Economic characteristics

Answer 3

• The Venezuelan economy is based on oil. 50% of GDP is generated by oil sales with the rest services. Being an urban area Caracas is focussed on services with banks, shops and national organisations based in the city.
• Being service focussed does little to help or hinder hazard response, other than the fact that each organisation/service often plans its own response rather than following an organised city wide plan.
• Economic divisions of late have led to rallies on both sides of the wealth divide asking for greater equality.
• The economy of Caracas would be badly hit by any future disaster as recent rapid growth means there are more people than the city can comfortably accommodate/employ. Any large event would likely lead to huge death tolls and current political instability could enable uncontrolled rioting/protests

Question 4

Political characteristics

Answer 4

. Government is democratic and relatively stable for South American standards
. High crime rate has moved government focus away from hazard prevention
. Most responses need political enforcement but there is a lack of funds and political control
. At risk slum buildings illegally built
. Slum people don’t have a dress so don’t vote so don’t care about what government says

Question 5

Community response to hazards

Answer 5

• Lack of equality in city means that different groups respond in different ways. There is little that the poorest residents who live in the steep barrios can do due to their low economic status and lack of opportunities/education
• Financial restrictions on the government mean that their preferred method of management is risk zoning. Designating certain high risk areas of the steep valley sides as ‘no build zones’. However, the effectiveness of this is limited by weak governance and the fact that most of the barrios (shanty towns) are constructed illegally
• Both affluent residents and those in informal/illegal housing are advised to orientate their buildings to be parallel to any debris flows so as to minimise the amount of material hitting the building and maximise its chance of surviving the hazard.
• Lack of education in barrios is being addressed to ensure they are aware of how to build in a safer way. This is to include ensuring there is spacing between housing and a focus on reducing the currently very high population density in these areas of 25000/km2
• In addition, laying streets out in the parallel pattern also assists in reducing risk.
• The wealthy residents of Caracas employ western builders and ensure their apartment/office blocks on the valley floor are built to strict western building codes. Very often they employ designers who have worked in California.
• The government funds research bodies such as the Venezuelan foundation for seismological research, which conduct research and experiments to assess the risks of different parts of the city. This has led to better knowledge of areas likely to be impacted by earthquake induced landslides and subsequently the implementation of new designs for new construction and reinforcement for old dwellings according to Hernandez (2007)

Question 6

Wealth

Answer 6

. Venezuela is the world’s 70th wealthiest nation with GDP of $17000. However, this wealth is very unevenly spread and poverty and crime is rife.

Question 7

Upper class

Answer 7

. First gained wealth and status in Venezuela through landownership and more recently through industry, commerce, and urban real estate.
. Their homes are luxurious and generally occupy the eastern margins of the valley and the Caribbean coast, these homes are built to high international standards and are therefore likely to withstand the earthquake hazard
. They are also far enough away from the steep valley sides to avoid the landslide risk.

Question 8

Middle class

Answer 8

Have developed largely in relation to the country’s petroleum wealth and recent European immigration. 
. Middle-class housing occupies the central core of the city, plus certain residential suburbs. 
. These houses are smaller and less well constructed but use modern technology and good materials

Question 9

Lower class

Answer 9

. Composed of labourers, servants, and the unemployed, occupies the hillside shantytowns overlooking the city from the west and south.
. These areas are hugely exposed to landslides, earthquakes and flooding.
. Little thought being given to safe construction

Question 10

Hazard risk

Answer 10

. Intersection of South American and Caribbean plate
. Half is accommodated by San Sebastian fault line
. 2cm/yr rate of plate motion at offshore boundary
. Population density of 12,000 persons/km2 and growth of 3.1% per year in Caracas
. Alluvium (river deposited sediment) - becomes liquid when flooded
. Only main road crosses fault line and goes through landslide prone valleys
. Caracas is coastal
. At risk of earthquakes (so tsunamis, land slides, liquefaction ) and tropical storms (so storm surges, flooding)