January 28, 2010

Catastrophe Model of Haiti Earthquake Casualties

The Haitian earthquake caused an estimated 250,000 fatalities—and disease, starvation and lack of medical care could push the death toll higher, a catastrophe modeling firm said.

Risk Management Solutions in Newark Calif., said the quake, which destroyed more than 4,000 buildings in Port-au-Prince alone, had limited impact on the insurance industry, but raises questions about the earthquake risk across the Caribbean, the potential of an earthquake on nearby faults, and what lessons can be drawn from an event such as this.

12 page pdf - RMS FAQ: 2010 Haiti Earthquake and Caribbean Earthquake Risk

RMS estimates approximately 250,000 fatalities as a result of the 2010 Haiti Earthquake. This is a best estimate based on the limited data available within 36 hours of the occurrence of the event and the immediate impacts of the earthquake—primarily building collapse. This preliminary estimate of 250,000 casualties could potentially increase over the coming weeks due to compounding factors, such as the spread of infectious diseases, lack of food and water, and limited access to medical care. On January 20, 2010, a representative of the aid group Partners in Health estimated that up to 20,000 people were dying each day due to the lack of medical care (specifically medical operations).

• Over 90 percent of the walls of Haiti’s buildings are constructed using either concrete/blocks, earthen materials, woven wood mats, or bricks and rocks. These heavy materials used to construct the walls, often with no reinforcement, caused numerous building collapses, resulting in extensive property damage and loss of life.

• While the primary damage from an earthquake is due to ground shaking, secondary hazards are phenomena that can cause additional loss to people and property at risk. The most relevant secondary hazards are liquefaction and landslide—both of which played a role in increasing Haiti’s damage and loss.

• According to a stress analysis, the latest quake has loaded up pressure on adjacent fault lines to the west of Port-au-Prince along the Enriquillo fault, which will be enough to trigger earthquakes on the adjacent segments—“particularly if those fault segments were close to failure prior to the January 12 earthquake.” RMS said.

• Stress calculations indicating a clustering of aftershocks at the western end of the rupture are reasonable since no significant earthquake has occurred along the adjacent segments in the last 150 years, the firm said.

• Of particular concern following the Haiti Earthquake is the damage to informal housing in shanty towns on the outskirts of Port-au-Prince. The firm noted that as rural poor migrate to the major cities, they often take up residence in shanty towns built with substandard construction that cannot stand up to the natural hazards that are present across so many capital cities—from hurricanes to landslides and earthquakes.

RMS said it is currently carrying out a new type of collaborative model development effort designed to quantify the economic and humanitarian impacts of future earthquakes on capital cities in developing countries, with South America as an initial test case.

According to the Institut Haïtien de Statistique et d'Informatique (IHSI or Haitian Institute of Statistics and Informatics) (IHSI, 2010), over 70% of the country’s building stock is low rise (i.e., one story in height). L’ajoupas or cottages (translated “country homes”) represent over 15% of the country’s construction, with much higher concentrations in rural regions (e.g., 92.5% in rural and 7.5% in urban regions). Multi-story buildings represent less than 10% of Haiti’s property at risk and are concentrated in urban regions.

Over 90% of the walls of buildings are constructed using one of four material(s): concrete/blocks, earthen materials, clisse (translated “woven wood mats”), or bricks/rocks; with all materials, there is often no reinforcement (e.g., steel rebar). In rural regions, earthen materials are most common; in urban regions, concrete/blocks are utilized for close to 80% of the built walls. Similar patterns are seen in flooring materials, with hard-packed earth in rural regions and concrete in urban regions. Close to 70% of roofs are constructed using light metal (i.e., tin).

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