Stanford geophysicist William Ellsworth is among a group of scientists, including Kang-Kun Lee of Seoul National University, who published a perspective piece May 24 in Science outlining lessons from Pohang’s failure.
What would a better approach look like? The potential for a runaway or triggered earthquake always has to be considered. And it’s important to consider it through the lens of evolving risk rather than hazard. Hazard is a potential source of harm or danger. Risk is the possibility of loss caused by harm or danger. Think of it this way: An earthquake as large as Pohang poses the same hazard whether it strikes in a densely populated city or an uninhabited desert. But the risk is very much higher in the city.
The probability of a serious event may be small, but it needs to be acknowledged and factored into decisions. Maybe you would decide that this is not such a good idea at all.
For example, if there’s a possibility of a magnitude 5.0 earthquake before the project starts, then you can estimate the damages and injuries that might be expected. If we can assign a probability to earthquakes of different magnitudes, then civil authorities can decide whether or not they want to accept the risk and under what terms.
As the project proceeds, those conversations need to continue. If a fault ends up being activated and the chance of a damaging earthquake increases, civil authorities and project managers might say, “we’re done.”
