On Earthquakes and Risks
Seven people, six of them scientist, were convicted of manslaughter yesterday and sentenced to six years in prison after over 300 people died in a 2009 earthquake in the Italian town of L’Aquila . They had been put on trial for not calculating correctly the risk of an earthquake, and over reassuring the population that a devastating quake was unlikely. Although their lawyer has said that they will appeal against the sentence, this conviction came as a surprise to the scientific community that rallied behind the accused scientists. Let’s review the chain of events.
Earthquake Swarms and Destructive Earthquakes.
Seismic activity along the Apennine mountains is very common. The quakes tend to be mild and only felt in a 20-30 km radius from the epicenter, but they can cause damage to ancient stone buildings, and every 10-20 years, a town along the Apennines is damaged.
L’Aquila is one of such towns. It was severely hit by earthquakes in 1461 and 1703, and the historic buildings had had several reconstructions after the last quakes that caused damage. Yet, the construction style and materials had been kept, making it a picturesque medieval town. In the outskirts, modern buildings have been built during the last few decades.
In October 2008, small tremors started being felt. They didn’t cause damage, but their frequency were making people nervous. By early 2009, the quakes were more frequent and stronger. This kind of tremors are called “earthquake swarms”, and are not uncommon in the region. They tend to disappear after a while without a major seismic event. Throughout these months, the Italian Civil Protection Department was present in the town, making plans in case of an emergency, and reassuring the population that the possibility of a destructive event was quite remote. Yet, there were people saying that a major earthquake was due any day.
In April, a stronger earthquake was felt. It didn’t cause much damage, but experts from the Major Risks Commission (National Commission for the Forecast and Prevention of Major Risks) were called in. The Commission, who’s mission is to assess the risks of natural disasters, convened for a few hours in L’Aquila, reviewed the data, and concluded that, although a major event could not be discarded, there were no signs of imminent danger. These conclusions were transmitted to the public, with an emphasis on the reassurances, and they were told to go back home to sleep and go on with their lives.
In the early hours of the next day, there was a 6.3 magnitude earthquake with an epicenter a few kilometers away. 315 people died, 1,500 were injured, and about 65,000 people were evacuated from their homes. Or what was left of them. People were afraid, shocked, outraged, and they felt betrayed by the authorities. The people who had predicted a major earthquake started to gain notoriety, specially a retired technician of the Geologic Observatory who was measuring radon emission with home-made detectors, following the footsteps of a group of researchers who believe that anomalies in radon gas emissions during earthquake swarms are followed by major earthquakes. He had posted online that a major earthquake was due any day. Some of the town’s elders had also been saying that a medium magnitude earthquake, according to ancient wisdom, had to be followed by a major event.
After the Quake
Soon after the terrible quake, some citizens filed criminal and civil lawsuits against the people responsible of how the emergency was handled. The six scientists plus the government official leading the Major Risks Commissions were accused of negligence, and of making a confusing and incomplete evaluation of the risks to the population. The Attorney General decided there were enough grounds to try them for manslaughter.
This is probably the first time a group of specialists has faced a trial for failing to detect the imminence of a natural event and giving the appropriate warning. The scientific community massively rallied behind the accused scientists. A letter of support, highlighting the fact that there is no reliable method of predicting the place and time of an earthquake, was signed by over 5,000 experts from around the world. The general feeling was of injustice, but most of the scientific community thought that they would not be convicted.
Seismic Activity in the Region and the Buildings in L’Aquila
Before talking about who was or wasn’t responsible for the loss of life, there are a few things we need to take into consideration:
- Some 20 years ago, L’Aquila was classified as a high seismic risk region, so very strict construction regulations were put in place. These construction regulations not only applied to new buildings, but also demanded that older buildings had to be checked and reinforced if necessary. A building reinforcement program for old and historic buildings had been approved and was awaiting funding.
- The damaged and collapsed buildings were not all historic buildings. Some of them had been built well after the strict construction regulations were put in place. The assessments that took place after the event have shown that many of these buildings did not conform to regulation and even had poor construction quality. Some of the old buildings rehabilitated after the regulation were even made more vulnerable because of the modernization.
- The Civil Protection Deparment had identified 550 buildings particularly vulnerable to damage by earthquake 10 years ago. No special precautions to reinforce, protect, or evacuate these buildings were taken.
- Considering that Civil Protection had ordered the evacuation of several buildings twice before, they feared that another false alarm might make more difficult an evacuation if more clear evidence of danger were to be detected.
- A study of earthquake swarms had shown that only in 2% of the cases, a medium intensity earthquake was followed by a destructive one. In the rest of the cases, either the swarms had gradually disappeared or a destructive quake was felt without a previous medium intensity quake.
Given all this, it seems like both the Major Risks Commission recommendations, and the decision by the authorities not to evacuate were the right ones under the circumstances.
Seismic Forecasts and Prevention of Seismic Disasters
There is an almost unanimous opinion among specialists that, currently, there are no reliable methods of forecasting the time, place or magnitude of an earthquake. There is research being done on different prediction techniques and it is possible that some types of earthquakes will be able to be forecasted in the not too distant future. But, at the moment, none of those techniques has yielded consistent results, including the measurement of anomalies in radon gas emissions.
Seismologists have been concentrating their efforts in estimating the characteristics of the earthquakes likely to hit a given place. Based on catalogs of historic quakes and the geologic evidence of great movements in prehistoric times, the probability of events at a given distance or of a given magnitude that can cause damage can be calculated. This way, the level of Seismic Hazard of a place is determined and the level of resistance that its buildings should have in order to have a very low probability of being damaged by the most severe event that could be expected. Every country in the world exposed to significant seismic activity has made zoning maps according to seismic risks, and determined construction regulations according to the assigned hazard of the area.
From this it can be concluded that protecting people and their property against seismic threats is essentially based on how safe are the buildings they live in and the objects they interact with in case of the most severe seismic events that can happen. This level of safety depends on the quality of construction regulations and how rigorously they are applied. It’s very common in the inspection of buildings damaged by earthquakes to find grave errors and omissions in following construction regulations and good practices.
In very specific cases, it is possible to install an alarm to alert the population that a strong earthquake is imminent. This system is not based on the prediction of the quake, but on the detection of seismic movements in places very near their origin (the epicenter) followed by an analysis of the signal to estimate the magnitude of the event. When the magnitude calls for it, a signal is sent to places farther away. This system would not be of much use in L’Aquila and nearby towns since they are located only a few kilometers away from the epicenter. The signal would not reach them before the beginning of the earthquake.
- Builders and developers who did not conform constructions to the regulations and best practices are clearly responsible for building and selling insecure housing. Those owners who renovated without introducing the seismic security improvements required by law are also at fault.
- The regional and city authorities are responsible for not prioritizing the rehabilitation of buildings that had been marked as very vulnerable, but mostly for not making sure new buildings were being constructed according to seismic regulations.
- Civil Protection authorities overly minimized the risk the city was in, which led the local authorities, and even the population, to not take precautions. Also, since the earthquake swarm was so persistent, they should have ordered an evacuation or the bracing of vulnerable buildings.
- The members of the scientific committee cannot be blamed for not ordering an evacuation, but they should have expressed their opinion in a formal document, where they could clearly communicate the risks and vulnerabilities of the city. Since they knew how vulnerable some of the buildings were, they should have recommended some precautions to the authorities.
- This being a seismic region, the population should have paid more attention to the risk their buildings were in. But given that there hadn’t been a destructive earthquake in over 300 years, their apathy is understandable.
What Has Been Done in the Aftermath
The response immediately after the disaster (rescue, medical attention, evacuation and relocation) was well executed. Some people are still living in the temporary housing.
The reconstruction and rehabilitation, although well funded, is painfully slow. The general criteria for risk mitigation established for the reconstruction are very sound, but there are still some decisions to be made in regards to urban planning and the preservation of cultural heritage. Part of what makes the process slow is the controls that were set to prevent poor quality construction. There has also been conflict between central and local authorities, and the population growing tired of the situation.
Scientists and specialists are working hard at studying the risks and planning the reconstruction work, but hardly ever talk to the press and are careful not to make their opinions or activities public.
A problem that has not been talked about much is what will happen to other places which face similar risks. There are thousands of towns in high seismic risk regions with similar risk conditions. These are not subject to the new regulations and would suffer grave damages in an earthquake. On the other hand, there are no resources to intervene in all of them and the probability of a destructive event is very low. Taking L’Aquila as a representative case, a rough estimate of the probability of risk can be made for the rest of the towns.
There have been destructive earthquakes in L’Aquila in 1461, 1703 and 2009. Almost 300 years in between destructive events. From this, rather unsettling and complicated ethical decisions have to be made. Is the population of these towns willing to put up with the inconvenience and costs of large scale city rehabilitation? The answer is probably yes, as long as most of the costs are covered by the central government. But what would the population in other regions say to paying a bill 10 times higher in the next couple of decades to rehabilitate the whole region? The answer might not be as positive.
The conviction of the members of the Major Risks Commission is a great injustice that will cause a drastic change in the willingness of scientists to advice authorities in cases of risk. The authorities love to say their decisions are backed by well-respected scientists, and many of them have been willing to do it because of the satisfaction and prestige that comes with positive results. From now on, they will be much more careful.
Note: This post is a slightly shorter version of a post that will be published tomorrow at Escéptica in Spanish. The information in it comes from an expert in the field.
Note 2: Just to be clear, this post is based on the opinions and knowledge of an expert in the area, who kindly collaborated with Esceptica/Skepchick to make this post possible.
Featured image is from here.