Tham khảo tài liệu 'basic recommendations for earthquake protection_15', khoa học tự nhiên, công nghệ môi trường phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | RISK MITIGATION INACTION 373 study established that occupants were willing to pay a rented accommodation increase of 20 per month for increased safety enough to pay for the cheapest upgrading option but that any higher cost would not be acceptable. The much higher standard of safety and significantly higher cost introduced in the Los Angeles regulations met strong resistance from building owners. Evaluating Targeted Strengthening The cost-effectiveness of strengthening can be further enhanced by targeting only the most vulnerable structures. In a pilot study in Mexico City screening of the building stock to target residents most at risk was carried out in a small area of the city to identify the worst 1 5 and 10 of the building stock in terms of its potential contribution to future casualty The concentration of population in high-occupancy buildings in Mexico City makes this approach relatively effective. In the event of a severe earthquake expected fatalities in the pilot study area would be reduced by almost 50 if the worst 5 of buildings had been strengthened giving a cost per saved life assuming the earthquake occurs of around 5000. The benefits of this strengthening programme referred to as programme I in terms of fatalities are shown in Figure . The calculated cost per saved life is also highly dependent on the severity of the assumed earthquake. There is a low probability of such a severe earthquake occurring within the lifetime of the strengthened building a less severe earthquake is more likely but an earthquake with a return period of only 25 years would cause fewer casualties and the strengthening would save the lives of fewer people and so the cost of per saved life would be of the order of 50 000. A larger scale programme programme II involving the strengthening of over 10 of the pilot area building stock would reduce expected fatalities by over 80 at a cost per saved life of 7000 again in the event of the most severe earthquake .
