By H. Kit Miyamoto, PhD SE and Amir SJ Gilani, PhD SE.
The M 7.8 earthquakes (Nepal 2015 and Ecuador 2016) caused massive damage to the built environment and affected societies severely. In Nepal, it caused over 9000 fatalities and destroyed over 600,000 structures. Economic impact is at a cost of roughly a quarter of Nepal’s GDP and it keeps increasing. The Ecuador earthquake resulted in over 600 casualties and injuries to close to 28,000 and triggered collapse of hundreds of structures, was felt at Quito, nearly 180 km away. This earthquake severely damaged the coastline of approximately 200 km long. Scores of cities and towns are damaged and economic impact to this small country will be large. Both earthquakes occurred on Saturday daytime. This reduced the number of causalities including schoolchildren. Over 7000 schools were heavily damages or collapsed in Kathmandu and several hundreds were damaged in Ecuador. In Katmandu, which is built in an ancient lakebed, far from the epicenter, site amplification resulted in large spectral acceleration at periods of 2 to 4 sec which inturn 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 starting. In Ecuador, Similar to Katmandu, many of affected cities such as Portoviejo are situated on soft soil and thus susceptible to site amplification. Not only older nonductile construction is again shown as dangerous, but also many modern code conforming buildings sustained nonstructural damages and plastic hinges and they cannot be occupied. Modern building codes may save lives but it certainly not able to provide resiliency in communities affected by major earthquakes. The society’s expectation is far higher than what are routinely provided by minimum code requirements of life safety.
Read the paper: Damage Assessment and Seismic Retrofit of Buildings Following the 2015 Nepal and 2016 Ecuador Earthquakes
