(Above: Carlos in the field)
Carlos Molina Hutt is a Teaching Fellow in Structural and Earthquake Engineering at University College London (UCL) and Vice Chair of the Earthquake Engineering Field Investigation Team (EEFIT). Following the April 16 M7.8 Earthquake in Ecuador, Carlos was deployed with the European Union Civil Protection Team to provide assistance. In this blog, he discusses his work in the country.
I travelled to Ecuador with the European Union Civil Protection Team (EUCPT) whose goal was to enable coordinated assistance to victims of the April 16 Earthquake, working alongside the United Nations Disaster Assessment and Coordination (UNDAC) team.
I was one of three structural engineering experts in the team. Our role was to work with the Ecuadorian Government in the post-earthquake safety evaluation of damaged buildings, as well as to coordinate the response of additional experts from other European countries. European teams assessed nearly 1000 buildings while on the ground. Other types of assistance provided are illustrated in the below map.
In my experience the Ecuadorian government had organised a strong and coordinated response to the disaster. Local authorities gave us access to detailed building inventories which helped ensure a coordinated response and avoided duplications of assessment work.
Our efforts were focused in Portoviejo, the capital of the Province of Manabí. The city centre was cordoned off by local authorities within 48 hours of the earthquake due to the extensive damage (see map below).
The types of structural assessments we carried out included:
Rapid Post-Earthquake Safety Assessment of Buildings:
A rapid assessment is a quick, but thorough evaluation of the risks that the damage caused to a building may impose on occupants and surrounding areas. Buildings were tagged as Green, Yellow or Red, as shown in the map. The implications of each tag are as follows:
-Green: A Green tag indicates that no damage observed during the inspection poses a safety risk for entry or occupancy of the building.
-Yellow: A yellow placard indicates that there are restrictions on the building usage. The restrictions are based on the inspection team’s judgment.
-Red: A red placard indicates that the building is unsafe for occupancy. However, it does not mean that the building must be demolished. In certain occasions, a building may be tagged as red due to non-structural damage only, or due to hazards from surrounding buildings.
This assessment was requested by the municipality prior to proceeding with demolition work in order to ensure that no buildings that could be salvaged would be demolished.
Safe Road Access through Zone Zero:
This assessment was intended to open up the arteries of Zone Zero to allow for a prompt reactivation of the economic activity in the city center.
Detailed Post-Earthquake Safety Assessment of Buildings:
Detailed evaluations follow the same tagging procedure as that noted in the rapid assessment, but entail a more thorough review. These were conducted for buildings like hospitals, schools and other public buildings.
Ecuador sits near the plate boundary of the Nazca and the Pacific plates, and has a history of large earthquakes. Seven earthquakes of magnitude seven or more have occurred within 250 km of this year’s earthquake since 1900.
Poorly built structures were a significant factor in casualties. While modern building codes exist in Ecuador, they are not strictly enforced. This was particularly common in low-rise residential buildings which were often of informal construction. However, some of the damage observed in multi-story buildings, such as those below, also revealed the lack of code enforcement and/or quality control in much multi-story construction. There is a clear need for a widespread enforcement of building codes, at least for schools, hospitals and other public buildings. Training of masons could also significantly improve the structural and non-structural performance of buildings, even those of informal construction.
I was particularly shocked by the amount of non-structural damage. In many instances, the structure had performed relatively well during the earthquake, but there was significant damage to interior partitions and the building envelope. These buildings had to be tagged yellow due to the hazard of falling debris. To save time and material costs, unreinforced clay masonry walls used in the building envelope had been constructed using a single layer of bricks, and by placing these on the long, narrow side (with the broad face of the brick exposed) such walls were extremely susceptible to seismic damage.
(Above; envelope damage)
The trip was a learning experience from start to finish. While on the ground, I realised that the greatest challenge when conducting post-earthquake safety evaluations is not the technical one, but rather understanding the context: the constraints of local knowledge and practice. Additionally, this kind of mission only lasts a few weeks, so it’s important to pass on skills to the local community where you can.
You can read more about the EUCPT’s work in Ecuador here