Fire Safety and Technology Editorial
Earthquakes and Building Codes
On January 12 of this year a dramatic earthquake shook Haiti and caused unbelievable severe destruction and 222,517 fatalities (official numbers). The earthquake was assessed at 7.0 in the Richter scale. A few weeks later, on February 27, an earthquake shook Chile and caused 279 fatalities (official numbers to March 5, which are likely to increase a bit). Interestingly, this earthquake was assessed at 8.8 in the Richter scale. The difference in intensity between an 8.8 earthquake and a 7.0 earthquake is a factor of roughly 700. This means that the earthquake in Chile was approximately 700 times more severe than the earthquake in Haiti but it caused some 800 times fewer fatalities. I am addressing this issue for two reasons: (1) I need to understand what caused this disparity and (2) the response to the first question affects fire issues.
There is a clear answer to the first question: buildings comply with reasonable building codes in Chile but not in Haiti. This affects fire issues because we should never back off from adequate fire safety regulation because of a lack of incidents. Let me elaborate.
The Chilean earthquake was the fifth strongest earthquake in the world for over a hundred years. This makes this one of the elite "mega-earthquakes", which means that it was hundreds of times stronger than other earthquakes near populated areas in recent years, with the exception of the 2004/5 Indonesian earthquakes/tsunamis. An attached Table shows all major earthquakes since 1980 with magnitudes of 6.8 and above 6.8 in the Richter scale. An attached graph shows that the Chile earthquake is the exception and not the norm and a good model to be followed (the only other two earthquakes within the same type of magnitude over the last 30 years were the Sumatra earthquake/tsunami of December 2004 and its aftershock). It may be of little consolation for the victims of the Chilean earthquake, but when a natural disaster of this magnitude hits, the number of expected deaths would have been vastly higher in most any other country in the world.
Reasons exist for Chile to have done so well (in relative terms). In 1960, the strongest earthquake in recorded history, a magnitude 9.7, struck Chile. After that earthquake, Chile revised its building codes and imposed strict rules about the quality of building materials. The government also invested heavily in research to find weak points in the soil under major cities. It has been stated that Chile has one of the most modern building codes in the world, and now we're seeing how the rules paid off.
Haiti is the poorest country in the Western hemisphere, and suffers from a significant amount of corruption. Building codes, if they exist at all, are ignored and are not based on either sound scientific or engineering principles and are not updated.
In the same way as in Chile, in California, people have been preparing for “a Big One” since the 1906 earthquake rocked San Francisco. A 1933 earthquake centered at Long Beach led to tougher building requirements for schools. The 1989 Loma Prieta (San Francisco) earthquake took down major bridges in the Bay Area and destroyed many buildings. As a result of these earthquakes, and of improved understanding of engineering technology, building codes have continued to evolve as we learn more about what buildings are dangerous and how the ground shakes under earthquakes.
We have also had, in the US, a man-made disaster: the September 11, 2001, terrorist attacks on the New York City World Trade Center buildings (Twin Towers). As everyone knows, terrorists flew a large aircraft into each one of the two towers, and they were both destroyed. That horrific tragedy resulted in the deaths of some 2,000 people present in the buildings (plus a number of firefighters and other first responders, for a total estimated at 2,750). The towers were built in compliance with the applicable building code at the time of construction. That is one of the key reasons that almost all the building occupants who were in the floors below the floor of aircraft impact survived and the vast majority of the fatalities were people who were present in the floors above the floor of aircraft impact. The Twin Towers have had upwards of 50,000 people in them on any given day. Moreover, no building code (at least before 2001) was ever developed for buildings to resist the impact of large aircraft and not collapse. Since 2001 there have been many studies on what could have been done better with the building code associated with the Twin Towers (with the key work having been conducted by NIST http://wtc.nist.gov/), and, more importantly, what could be done better in future.
In the US there is a system of codes (including building codes) that are revised periodically, with open technical discussions, where all interested parties are involved. This permits the best new ideas to be put forward and implemented into requirements that will then become regulations.
Typically, proposals are made for improvements in safety. It is very common that those responsible for implementing such proposals demand evidence that a safety problem exists and that public safety requires improvements in safety. The onus is, usually, on the proponents to demonstrate this need, either through loss statistics or through analyses of performance of existing materials/systems.
On the other hand, it is not unusual for proposals to be made, to regulations and/or codes and/or standards, that certain fire safety provisions be loosened because there is no evidence of a lack of safety, since no losses (or few losses) are occurring. These proposals are even, occasionally, accompanied by statistics indicating that there are no (or low) losses in certain areas. This argument is very dangerous. Safety measures in effect often result in increases in unquantifiable safety effects because it is almost impossible to quantify the losses that do not happen. It is essential to be extremely vigilant so that safety measures (for example in regulations, codes or standards) are not loosened. Before an existing safety measure is eliminated there should always be proof that it was inadequate and that its elimination will not cause a decrease in public safety.
The massive earthquake in Chile caused untold suffering and many fatalities: it was a serious tragedy. However, when the outcome in Chile is compared to the outcome in the much milder Haiti earthquake, it becomes an example of how a lack of losses should never be used as an excuse for lowering safety requirements. But that’s just my opinion, and I invite other opinions.
Marcelo M. Hirschler
