By Zhang Bin
Published: 2008-05-23

The collapses of public buildings, such as schools and hospitals, caused by earthquakes were avoidable if more investment had been made in structural design and construction material, said disaster reduction and engineering experts around the world.

The May 12 earthquake in Sichuan, China, measuring 8 on the Richter scale, had claimed over 55,000 lives as of May 23. Many students and teachers were killed as schools collapsed, drawing public outcry over the safety of public buildings and earthquake alarm mechanisms.

Though agreeing that no technology to date could predict future earthquakes and effectively warn the public, experts in the field said preventive measures such as having quake-resistant structures could have prevented huge losses of life and property.

Damage Control Possible
Carlos Estuardo Ventura, director of Earthquake Engineering Research Facility under the Civil Engineering Department of Canada's University of British Columbia, said technology was available today to resist shaking, thus controlling damage and collapse, produced by an earthquake of high magnitude as experienced by China recently.

He said it was inevitable that earthquake would occur again, and again, but devastation could be avoided as the building collapse generally resulted from a combination of severe shaking, poor structural design and improper use of construction materials. 

"It is also imperative that the government insures a safe construction of schools, hospitals and other buildings that house emergency response groups.

"The rebuilding not only entails construction of new buildings and repair of damaged ones, but also rebuilding the confidence of the Chinese people," Ventura said in an email interview with the EO.

As to speculations that the frequent aftershocks showed signs of the earthquake force moving northwards, Ventura explained that aftershocks tend to occur in a certain direction with respect to the epicenter of the main shock, but each aftershock had its own epicenter.  

"The magnitude of the aftershocks tends to be less than the magnitude of the main shock as the time passes. However, there is always a possibility that another nearby fault may become active and generate another earthquake of similar magnitude," he said. 

Prediction Impossible; but China has a Record
Unesco's Disaster Reduction Section Chief Badaoui Rouhban, who is based in Paris, said it was impossible to predict the day and location of an earthquake.

However, based on in-depth seismological researches and observations, it would be possible to estimate the probabilities for the occurrence of potential future earthquakes in a givern geographical location.

For example, he added, scientist were able to estimate that over the next 20 or 30 years, the probability of major earthquakes in Istanbul (Turkey), Tokyo (Japan), Tehran (Iran), Chile in percentage chance of occuring.  

In fact, he stressed, China held the world record as the first country to have successfully predicted and avoided a destructive earthquake in Haicheng, northeast of China, in 1975.

The 7.3-magnitude earthquake hit Liaoning province on Feb 4 1975, and though Haicheng was a densely populated city few lives were lost thanks to predictions based on geophysical observations of precursor events and abnormal animal behavior. The public was forewarned, prepared, and thus losses kept to minimum. 

On why so many buildings collapsed during the May 12 earthquake, Rouhban explained that a combination confluence of factors worsened the damage beyond simply the earthquake's magnitude..

"The small depth of the earthquake focus (less than 10 kilometers beneath the surface) which make the earthquake a 'shallow' one and thus the waves reach the surface and the building more quickly and strongly.

"The inappropriate resistance of some buildings and their foundations and the unfavorable condition of soil," he also played a role, he said, adding that buildings could be constructed to withstand such a magnitude but the cost would consequently be higher.

The United Nations' International Strategy for Disaster Reduction Director Salvano Briceno, who is based in Geneva, said he was impressed by China's rapid emergency response.

He said construction of resistant buildings would be an important measure, adding China had an active National Committee for Disaster Reduction already working on these issues.

For full interview text: click here