Over the years the Earthquake Engineering Field Investigation Team (EEFIT) has travelled to Pakistan, Japan, Peru, Turkey, Italy and New Zealand to investigate and report on engineering issues relating to earthquakes. Harriette Stone recently travelled to Ecuador with the team, to report on the recent earthquake in the country – here she updates us on the team’s mission.
EEFIT sends reconnaissance missions to areas affected by earthquakes, to learn engineering lessons from the failure of buildings or soils. These lessons can relate to issues with design codes, materials, construction methods – any factors from which we can learn and propose solutions and/or improvements that will help make structures more resilient in future events, and contribute to the study of earthquake engineering.
Ecuador sits near to the boundary between the Nazca plate and the South American plate, and therefore experiences frequent earthquakes, but this is the first time EEFIT has sent a team to the country – following the 7.8 magnitude earthquake on April 16 2016.
I was part of the structural engineering sub-group in the EEFIT team - there were also geotechnical engineers and a social scientist included in our mission. We travelled to the affected provinces of Manabí and Emeraldas, which are large coastal areas where the earthquake damage was most severe.
The Ecuadorian military were in charge of most of the initial response, providing food and water in the immediate aftermath, managing the assessment of the safety of structures, leading the demolition process and providing temporary shelters for displaced people.
The majority of buildings observed were reinforced concrete structures with masonry infill walls, and timber structures. The main faults in the concrete structures was to do with lack of seismic specific design, and in some cases the quality of materials and the construction. Timber structures were mostly damaged due to issues caused by poor maintenance, resulting in rot and insect infestation.
It was hard for us to attribute casualties to specific building failures, but reports indicate that failures in both the structural and non-structural parts of buildings were responsible for the vast majority of casualties from the earthquake.
There was one major structural failure of a bridge, hundreds of kilometres from the epicentre in Guayaquil, Ecuador’s largest city. Notably, the ‘Los Caras’ bridge, which links Bahía de Caráquez and San Vincente - constructed recently with base isolation systems - survived the earthquake shaking with minimal but repairable damage. This bridge was a key route for the initial humanitarian response to the affected area.
Our team is working on a full report to publish at the end of July on the website, and we will present our findings at an EEFIT technical meeting in September. We will also present a paper at the World Conference of Earthquake Engineering in Chile in January 2017. However, the following simple points would help improve the future behaviour of structures in this earthquake prone region:
• Better understanding of the design requirements of reinforced concrete buildings
• Improved education about the maintenance of timber structures
• Better building control procedures to improve material and construction quality
The lasting memory that I will take away from my time in Ecuador will be the people. Ecuadorians, despite having suffered greatly, were more than happy to share their experiences, however painful.
Learn more about EEFIT, and read reports from previous expeditions, here.