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EXPOSURE MODEL FOR BOGOTÁ D.C., ANTIOQUIA AND METROPOLITAN AREA OF CALI

Colombia has a considerable seismic risk as it is located in a seismic active region; the majority of the population is exposed to medium and high seismic hazard; and an important percentage of the building stock is seismically vulnerable. The three biggest cities of Colombia are Bogotá D.C. (7,878,783 inhabitants), Medellín (2,464,322) and Cali (2,369,829). Bogotá D.C. and Medellín have medium seismic hazard, whilst Cali has high seismic hazard. The number of inhabitants in these three cities represents 26% of Colombia’s population. The next figure presents the geographical location of Bogotá D.C. (capital of Cundinamarca department), Antioquia department (whose capital city is Medellín) and the metropolitan area of Cali (Palmira, Yumbo, Jamundí, Tuluá, Candelaria), which is located in the Valle del Cauca department.

The development of the exposure models required information about built-up area, distribution of number of storeys and structural system, socio-economic strata, population and replacement cost. As different data was available for each considered region, the methodology for the model development differs between regions. Similarities between the models are described next. Particular information for each region is detailed further.

Exposure model development

Building classes considered in the exposure models were defined in terms of material and lateral load carrying system (GEM taxonomy was used for building classification) as shown in the following table. In addition to the parameters of the table, building number of stories, defined as HEX, was included in the building class definition. Details of the number of stories considered for each region are given in the exposure models files for Bogotá D.C., Antioquia (Medellín, Aburrá Valley and other municipalities), Cali and metropolitan area of Cali.

Replacement cost for the studied regions was considered as function of the socio-economic strata (Colombia’ social strata is divided from lowest to highest income in a scale from one to six) as shown in the following table. For those regions were distribution of socio-economic strata was not available, a unique value was assumed. Replacement cost refers to the cost of structural and non-structural components of a building and it is a value associated to building rehabilitation. This value differs from the commercial value, as land price is not included. It must be kept in mind that after a seismic event, a structure must be repaired according to modern seismic regulations, regardless its structural system.

As the exposure models are developed in terms of built-up area, additional information is required in order to define the number of dwellings and the number of buildings. Typical dwelling area was defined as function of building typology and socio-economic strata. The number of buildings was defined in terms of the average number of dwellings for each building typology and the number of stories. The following tables present average dwelling area and average number of dwellings used for all of the studied regions.


Exposure model of Bogotá D.C.

Bogotá D.C. is the capital city of Colombia and the Cundinamarca department. Bogotá is the largest city of Colombia with an area of 1,636 km2 (414 km2 urban and 1,222 km2 rural) and a population estimated to the year 2015 of 7,878,783 inhabitants. Bogotá D.C. has approximately 33 kilometres on the North-South direction and 16 kilometres in the East-West direction. City coordinates are 4°35’36” N and 74°04’51” W. A cadastral map of the year 2015 with information about built-plan area, number of stories and type of use was available, as well as information about socio-economic strata and population. The exposure model of Bogotá D.C. (exposure_model_bogota.csv) includes information for 1032 urban neighbourhoods. Data of each neighbourhood includes its name, location, number of inhabitants, total built area for each structural typology, number of dwellings, number of buildings and replacement cost.

Building typology distribution

Structural system distribution was defined as function of the socio-economic strata and the number of storeys based on data gathered from 1359 surveys specifically done for this study and expert judgement.

A summary of the exposure model of Bogotá is shown in the next table. Total replacement cost was estimated as 173,547,417 million of Colombian Pesos (COP). The figure shows replacement cost distribution in the city.


Exposure model of Antioquia

The department of Antioquia is located in the central northwestern part of Colombia. Its population comprises 13.3% of Colombia’s population. The capital of Antioquia is Medellín, the second-largest city in Colombia, whit a population of 2,464,322 inhabitants (estimated for the year 2015). Antioquia is divided in 125 municipalities, which are grouped in nine sub-regions. Medellín is part of the Aburrá Valley (Valle de Aburrá) sub-region, in which 58% of Antioquia population is settled. The following figures indicate the distribution of both the sub-regions and the municipalities within each sub-region.

Three different exposure models were developed for Antioquia based on the available information: models for Medellín, Aburrá Valley and other municipalities. Information presented next summarizes the assumptions used for models development. More detailed information can be found in the publication "Methodology for the development of a seismic exposure model of Antioquia (in Spanish)".

Medellín has the more detailed model (exposure_models_replacement_medellin.csv) as it is described for each neighborhood (350 neighborhoods). The Aburrá Valley has ten municipalities, one of them is Medellín. The exposure model described for the Aburrá Valley (exposure_models_replacement_aburra_valley.csv) was applied to all of the municipalities of the sub-region except Medellín (as Medellín has a better model). The remaining 115 municipalities of Antioquia, referred as other municipalities, have the less accurate exposure model as several assumptions were required due to lack of information (exposure_models_replacement_antioquia.csv).

The following table summarizes available information for each exposure model:

In those cases were information was not available (N/A) the following assumptions were made:

Exposure model for Medellín and the Aburrá Valley:

  • Structural system distribution: Building typology was defined according to the number of storeys and socio-economic strata. Structural system distribution was defined based on expert judgment and data collected from surveys done for the microzonation study of Medellín and the Aburrá Valley.
  • Replacement cost: Cost was assigned according to the socio-economic strata. It was defined based on expert judgment.

Exposure model for other municipalities:

  • Built area for municipalities without cadastral information: Built area was gathered from aerial pictures.
  • Building height distribution for municipalities without cadastral information: Same distribution from a similar municipality (in terms of population and area) with cadastral data was used; if required, data was gathered from virtual visits.
  • Structural system distribution: From data gathered from virtual surveys of the most populated municipality of each sub-region. The distribution of the most populated municipality was used for all of the municipalities of the sub-region, slightly modified according to census data.
  • Replacement cost: Unique value (regardless socio-economic strata). Based on expert judgement.

Building typology distribution

Building typology distribution was defined in terms of socio-economic strata and number of storeys. The following tables show the distribution used for the municipalities of the Metropolitan Area. The distribution used for the municipalities outside the Metropolitan Area can be consulted in the master thesis "Exposure model of residential buildings of Antioquia department, Colombia (in Spanish)".

Total replacement cost of the department of Antioquia was estimated as 135,138,072 million of Colombian Pesos (COP). 57% of the cost corresponds to the city of Medellín (76,386,242 million of COP). The Aburrá Valley has a replacement cost of 97,283,985 million of COP. The following figure shows replacement cost for the three developed models.


Exposure model of the metropolitan area of Cali

The city of Cali (Santiago de Cali) is the capital of the Valle del Cauca department. Cali is the most populous city in the Southwestern Colombia with an area of 564 km2 (120.9 km2 urban) and a population estimated to the year 2015 of 2,369,829 inhabitants. Cali is located at latitude 3°27’26” N and longitude 76°31’42” W. Six municipalities constitute the Metropolitan Area of Cali (Cali, Palmira, Yumbo, Jamundí, Tuluá and Candelaria). Urban population estimated for the year 2015 of the municipalities is of 2,333,213 for Cali; 244,406 for Palmira; 102,836 for Yumbo; 81,474 for Jamundí; 182,674 for Tuluá; and 22,705 for Candelaria. The urban inhabitants of the metropolitan area of Cali comprise 64% of the population of the Valle del Cauca department.

Cadastral data whit building resolution was available for the municipalities of Palmira, Yumbo, Jamundí, Tuluá and Candelaria. As cadastral data was not available for the model of Cali, two different exposure models were developed for the region: a model for the city of Cali (exposure_model_cali.csv) and a model for the remaining municipalities of the Metropolitan Area ( exposure_model_met_area_cali.csv).

Number of buildings and building typology distribution

The exposure model of Cali includes information of 329 urban neighbourhoods. As no cadastral map was available, the development of the model required significant efforts. A map of built-plan area of block of the city was available. Five different homogeneous zones were defined for the city as function of socio-economic strata and location (East or West). A total of 3222 buildings of the city were surveyed in order to gather data to defined number of storeys distribution and structural system distribution. The following tables present both distributions for the city of Cali.

Building typology distribution for the Metropolitan Area municipalities is shown in the next table. For those municipalities a cadastral map with information about number of storeys was available.

Summaries of the exposure model of Cali and the other municipalities of the Metropolitan Area are shown in the next tables. Total replacement cost was estimated as 44,898,183 million of Colombian Pesos (COP) for the city of Cali and 13,118,320 for the remaining municipalities of the Metropolitan Area. The figure shows the replacement cost distribution in the city and the Metropolitan Area of Cali.

  • risk/detailed_exposure/risk_colombia.txt
  • Last modified: 2016/03/17 12:44
  • by Catalina Yepes