by Bernarda Carranza
Quito, Sunday April 17, 2016, one day after: the memory is still vivid in our minds, almost palpable. The silence of the minute after continues to echo through the streets. Phones ring and vibrate all over Ecuador, connecting call after call, and the story from the night before is told over and over again, as if already learnt by heart; friends and families share what they experienced. Others desperately search for loved ones in the areas worst hit. Eyes glued to smart phones for updates: How many people died? How many wounded? Which regions were worse affected?
Statistics, numbers, totals are shared and re-shared across every possible form of social media as relief efforts for our “brothers on the coast” get rolling.
That same Sunday, another group of Quito residents, met to discuss the same thing – the magnitude 7.8 earthquake that had occurred on the coast – but they discussed the event with dry eyes and strong hearts. The statistics certainly affected them, but what they were concerned about was something more complicated, something deeper, hidden beneath the fractured streets and layers of asphalt, 20 km below the surface.
Seismologists, geophysicists, volcanologists and geographers from the IRD and the Instituto Geofísico (IG) want to stand face to face with the giant who caused this catastrophe. They know they will soon have to stand before the Ecuadorian people and the media, who will turn to them in search of answers: why did this happen? When will it happen again? Is a bigger earthquake coming? Why here?
While many Ecuadorians are busy organizing relief efforts to our coast, the scientists from these institutes set out to recuperate their monitoring equipment’s vital information. On Monday, the day after the terrible quake, both the humanitarian and scientific missions began their journey to ground zero.
The project
The ADN (Northern Andes) project was born in 2008 and set out to study the processes that cause strong earthquakes in the Pacific region. The regional seismic activity is monitored through 10 stations located at various points in Esmeraldas and Manabí provinces (where a greater probability of earthquakes had been predicted before the stations were created).
Seismographs, GPS and Accelerometers
Monday the 18th, two days after: Paúl Jarrin, Frédérique Rolandone and our photographer Juan Pablo Verdesoto head out in an IRD car to search for and recover all the seismic recordings from the seismographs, GPS and accelerometers located along the coast.
The journey begins in Quito and passes by each “station” (Quininde, Punta Galera, Muisne, Mompiche, Pedernales, La Chorrera, Punta Prieta, Jama and Bahia). The drive, long and tiring, is eased by Frédérique’s French music. Yet, the mission is only just beginning with the search for that white, metal box containing the monitoring instruments. The researchers sometimes take two hours to cross rugged terrain in uncomfortable weather conditions and overwhelming heat, in what soon becomes a quest for a holy memory card. The memory card contains all the information. Once it is found, it is replaced to continue monitoring the area (specifically to record the aftershocks) and the old one is loaded into an “all-terrain” laptop, in order to send the data back to the institute in Quito.
Sleeping in tents, a neighbour’s house or a hotel, if they are lucky, provides them with two or maximum three hours’ sleep. But as they get closer and closer to the epicenter, the real challenge is finding equipment still intact. Several boxes are completely destroyed, buried under wreckage without any seismic recordings. Ironically in Pedernales, the epicenter, the instruments were completely undamaged… Paúl, Frédérique and our photographer begin to take in for the first time the reality and magnitude of the natural and human disaster that took the lives of more than 600 people.
As night falls, they are forced to make camp alongside coffins.
The more the merrier
The IG’s technical team embarks on a journey to place more seismic stations. Ecuadorians throughout the country are informed of the magnitude and location of the earthquake’s aftershocks through the real-time data that these pieces of equipment collect. A seismic sensor detects the tremors, a digitizer records the data, and a radio and antenna transmits the information back to Quito. In Manta, the building where one of the stations had been installed, collapsed. “The building was off-limits. We entered at our own risk,” remembers Cristina Ramos, head of the technical department.
Several days later, IRD seismologists, together with international observers and fellow scientists from the United States, reach the area to study the aftershocks both on land and at sea.
Cracks and uprisings
Tuesday 19, three days after: The IRD volcanologist Jean-Luc Le Pennec teams up with a group of geologists aiming to understand the surface deformation of the affected areas. Despite not being a specialist in the matter, he joins the effort: “arms, brains and cars are needed,” he tells us.
The roads to Pedernales have risen and the scientists mutter the term “reverse fault.” The deformations seem to lead everyone to that conclusion. A reverse fault is when the surface instead of creating a gap, rises. At ground zero, the roads have risen 60 cm and have moved horizontally 15 cm (this is known as crust shortening).
Just by watching the roads and wrecked cars stuck in the cracks, scientists understand the severity of the deformation. The subduction occurred 20 km deep and it was so powerful it made the soil press firmly, horizontally, and inward, like squashing a balloon at its ends until it pops. Similarly, the crust is pushed up 20 km and moves vertically.
Withering heights
Wednesday 20, four days after: Matthieu Perrault, IG researcher, leads his team to the area to conduct a study of the structural damage caused. His aim is to draw an “intensity” map of how the earthquake affected people and buildings.
Unlike magnitude, an intrinsic value that defines the earthquake as a whole, intensities vary depending on the location. In the epicenter, intensity is greater and therefore the damage greater. While in an area 200 km away, damage is less but the magnitude remains 7.8 on the Richter scale.
For Matthieu and his team, the day out in the field begins at 8:00 am and ends at night. They want to cover villages and neighborhoods in the day to take advantage of daylight. They divide into six groups, to cover an area from north to south that spans Esmeraldas to Salinas, and extends east to Latacunga and Ambato. Collapsed columns, entire buildings destroyed and debris everywhere, intensity is concentrated in Pedernales. The scientists are struck by the panic people must have felt, unable to walk or stand while witnessing the city topple over, everything shaken by the violence of the movement.
“This is personally an experience I will never forget. It was my first very strong earthquake,” says the French engineer.
Some buildings are completely destroyed. A few meters away, other buildings show minimal damage. This is the “topology of the buildings,” explains Matthieu. Certain structures are more resistant to an earthquake than others. Cement and wood buildings are more vulnerable in Ecuador (however, in other countries, there are building codes that ensure the resistance of the wood). Another factor is the date of construction. For older structures that have survived previous earthquakes, an earthquake like this is like another nail in their coffins. Other razed buildings are not designed correctly and do not comply with local building codes. Cutting costs by employing less reinforcement material in the concrete has the foreseeable consequence of making constructions considerably weaker.
After the fact
It is often only after a major earthquake that people become aware of the damage these events cause. This was the case in the United States, Japan or Chile following strong earthquakes in the 20th century. We know today how to build earthquake-resistant buildings and all new buildings must follow the norms. We must avoid building on vulnerable ground, as we know from this earthquake that the same movements will repeat themselves. Awareness is key to creating safer cities.
Grounded soil
Wednesday, May 18, a month later: In a Geophysics Institute car, seismologists Hugo Yépes, Jose Manuel Marrero, Patricio Ramón and Pablo Palacios reach Portoviejo. A month has passed, people are still desperate, and very insecure. A group crowds around the car seeking answers:
“How long will this last?” they ask.
The aftershocks to date exceed 1,500. The memory of the earthquake is still fresh in everyone’s minds, leaving no-one at peace. The ground continues to shake.
The seismologists measure the seismic response of the soil in Portoviejo. They bring with them seismic sensors to record the earth’s underground “noise”, which reveals seismic movement; a digitizer to gather the information that the sensor registers; GPS to measure the station’s location; solar panels and batteries. After each aftershock, waves travel through the soil, providing the scientists with valuable information that will help them to understand the soil’s response.
The process takes days and the community becomes involved, since the stations must be created in safe, enclosed places where solar panels can be installed, preferably inside someone’s house. The team is able to get seven stations up and running around the city, near the river and in the nearby woods.
Although one associates the ground being compact, this is not always the case. “There are more permeable soils, which are more likely to let water through and thus will behave differently during an earthquake,” says seismologist Pablo Palacios. “Soils that are soft, or have clay tend to be more moist and amplify waves more than drier soils. They can actually turn into virtual jello. When this type of soil is shaken by a quake, it vibrates and jiggles longer than solid soil”.
This information is key to safe construction. Constructing multi-storey buildings on softer ground is hazardous. This truth is borne out by the aftermath of the April earthquake, with the most serious damage occurring in the central areas of the city and near rivers, where the ground is more moist and therefore more vulnerable… Contention walls and land-fill is used to fill in the ground along the banks of rivers, allowing roads and houses to encroach closer. But when an earthquake hits, the walls cave in, the landfill gives way and whole blocks of housing collapse. Less damage was registered in areas where the ground is more compact or rocky.
An immediate response
The earthquake took the laboratory to the towns and cities of the Ecuadorian coast, as the scientists and researchers began their field work on ground zero, witnessing the damages caused by something that it many cases, they had only analyzed on computers, charts, graphs and theoretical discussions up until then. Their heroism, if humble and silent, will provide communities and countries with the data to help us understand more deeply the seismic nature of this earthquake, and indeed the entire Pacific “ring of fire”: an invaluable asset for our future, and key for confronting natural disasters. Even though we may fear them, they are an inevitable part of our natural laboratory.
Four axes
Our scientists’ mission can be divided into four major axes: to collect all the data recorded during the earthquake and its aftershocks; to set up new stations with instruments that can better understand and locate the aftershocks; to understand the relationship between the seismic waves and the damage (the floor and the buildings’ responses); and to measure surface deformations.
