H. Kit Miyamoto, Ph.D., SE and Amir SJ Gilani, Ph.D., SE
The M-7.8 earthquakes (Nepal 2015 and Ecuador 2016) caused massive damage to the built environment and affected societies severely. In Nepal, the earthquake caused nearly 9,000 fatalities and destroyed more than 600,000 structures. Economic impact was roughly a quarter of Nepal’s GDP and keeps increasing. The Ecuador earthquake resulted in more than 650 casualties and close to 28,000 injuries and triggered the collapse of hundreds of structures; it was even felt in Quito nearly 180 km away. This earthquake severely damaged the 200-kilometer-long coastline. Scores of cities and towns are damaged and economic impact to this small country will be large. Both earthquakes occurred on Saturday during the daytime. This reduced the number of causalities, including schoolchildren. More than 7,000 schools were heavily damaged or collapsed in Kathmandu and several hundred were damaged in Ecuador. In Katmandu, which is built in an ancient lakebed and was far from the epicenter, site amplification resulted in large spectral acceleration at periods of 2 to 4 sec, which in turn excited the large or tall buildings with fundamental periods in this period range, resulting in significant damage to these modern concrete buildings. After almost one year of political and environmental stalemate, reconstruction is just about to start. In Ecuador, similar to Katmandu, many affected cities such as Portoviejo are situated on soft soil and thus susceptible to site amplification. Not only was older non-ductile construction again shown to be dangerous, but many modern code-conforming buildings sustained structural damage (flexural hinging of members) and nonstructural damage that resulted in the loss of occupancy for these structures. Modern building codes may save lives but certainly are not able to provide resiliency in communities affected by major earthquakes. Society’s expectation is far higher than what is routinely provided by minimum code requirements of life safety.
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