Ecuador Earthquake: Building Codes Very Good, problem is enforcement says Stanford Professor

engineering.stanford.edu/By Corey Binns writes…Days after the recent magnitude 7.8 earthquake that shook Ecuador, three Stanford researchers flew to the country to study the damage and learn from the recovery efforts. The temblor on April 16 triggered significant destruction and killed an estimated 660 people and injured more than 27,000 more.

“Large earthquakes like these are, fortunately, very rare,” says professor Eduardo Miranda, who led the team from Stanford’s Blume Earthquake Engineering Center. “Even though we’ve made a lot of progress improving design codes and we do lots of testing to see how buildings might respond in an earthquake, there are lots of things we still can’t test in a laboratory.”

In particular, Miranda and his team have been studying the safety of hospitals, airports, bridges and other structures in the affected region of Ecuador. Working with colleagues at the Escuela Superior Polítecnica del Litoral (ESPOL) and the Catholic University of Santiago of Guayaquil, the Stanford researchers spent much of their time traveling the country and taking thousands of photographs to document structures that survived, and those that didn’t.

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Structural engineers from around the globe will spend the next several months gauging the safety of hospitals, police stations, fire stations and other large public buildings. Ecuadorians need these buildings to reopen quickly, but they must be safe before they can be reopened.

“The building codes in Ecuador are very good,” says Miranda. “The problem is that enforcement isn’t very good.” He said construction crews may often not follow structural drawings designed by structural engineers. “The earthquake finds these mistakes.”

Miranda and Andres Acosta Vera, an Ecuadorian Stanford graduate student, were eager to investigate one success story: the survival of the 2-kilometer-long Los Caras bridge that spans the Chone River, a major river that runs through the earthquake’s epicenter. The bridge opened in 2010, to speed up the commuting time of people in the area and promote tourism. It was built using a seismic isolation technology, a roller system between the ground and the bridge that prevents the ground motion from introducing deformation in the bridge. The Stanford team credits this technology with keeping the bridge fully intact.

“Without the bridge the earthquake would have cut the affected part of the country in two,” Miranda says. The bridge gave rescuers faster access to people trapped in the rubble and sped up the delivery of aid to those in need. “The bridge behaved exactly how we were expecting it to.”

The bridge gives Vera promise for future construction in his country. “The bridge’s good behavior will give more confidence to structural engineers in Ecuador to do structural designs using this methodology in the future, and also to the country officials in charge to invest in this type of technology given its cost-benefit,” says Vera. Elsewhere on the reconnaissance trip, Vera was saddened and shocked to see some of the places he used to stroll by now destroyed. “After I’m done with my graduate studies, I will go back to my country with all I have and will learn at Stanford, and will do my best to make a difference by addressing the problems we saw in this trip.”

One of the jobs for this Stanford team and other post-earthquake building evaluators will be to distinguish between superficial damage and unsafe conditions at hospitals. It’s of utmost importance that hospitals remain open during and after an earthquake. Yet, officials had to evacuate two hospitals with a total of approximately 300 beds in the city of Manta, near the epicenter, and one 100-bed hospital more than a hundred miles away in Guayaquil. A lot of these damages are cosmetic and, while they will need repair, they have not impacted the structural integrity of the hospitals.

Other buildings, however, have been weakened significantly and an aftershock could send them crumbling to the ground. Every day, a dozen aftershocks hit the already shaken region. In four days following the main shock of April 16, 22 earthquakes of magnitude 4.5 or greater hit Ecuador.

“It’s key during this time to ascertain the safety of buildings in order to protect against further deaths and injuries linked with the occupation of dangerous buildings, or conversely to reopen critical infrastructure if safe,” says Stanford engineer and researcher David Lallemant.

Unfortunately, the port in Manta sustained major damage and remains only partially operational. “Repairing the port will take more than a year,” Miranda predicts, and the country’s export of tuna, shrimp and other fish will take a significant hit during the reconstruction project.

Another job for Miranda and his colleagues is to try to understand why buildings behaved the way they did. One member of the Ecuador team, PhD student Luis Ceferino, hopes to pinpoint the main vulnerabilities of hospitals, both in terms of structural design and operational responses to a disaster.

“As bad as the earthquake damage was, it was fortunate that it didn’t affect large concentrations of population,” says Miranda. Cities close to the epicenter aren’t the country’s largest. “But the big lesson is to be prepared for an earthquake closer to Guayaquil. Large earthquakes close to large metropolitan regions are what we fear the most.” Read Article