20110327 Learning from Japan’s earthquake

Learning from Japan’s earthquake

By Jerry Huang 黃永進

The powerful earthquake that struck off the coast of northeastern Japan on March 11 has caused Japan’s greatest disaster since World War II, and it has stoked fear in Taiwan, which lies on the same earthquake belt and suffered the devastating 921 Earthquake in September 1999. Many media and Internet commentators are observing the two earthquake disasters and comparing how the governments and public of Japan and Taiwan responded to them, and asking what would happen if Taiwan found itself in a similar situation to that which Japan now faces.

It is often possible to learn from the experience of others, so making such comparisons ought to be a good thing for Taiwan. For comparisons to be fair, however, they should be based on specialist knowledge that permits an accurate appraisal of Taiwan’s existing mechanisms for reducing earthquake damage and mitigating disasters. What we don’t need is for people to just parrot whatever they hear, spreading disinformation and causing panic.

I have been conducting research on how earthquakes affect tall buildings for a long time, so I would like to offer a few points of advice, from a professional angle, that will hopefully help everyone to get the right idea about earthquake damage.

The first point is that Taiwan is a world leader in knowledge about earthquakes. There is no need for us to belittle ourselves in this respect. Taiwan has a comprehensive nationwide earthquake detection network. The Taipei 101 skyscraper, one of the tallest buildings in the world, incorporates advanced equipment that can analyze and respond to seismic motion. We gained a lot of experience from the 921 Earthquake, and we have plenty of experts who are experienced in earthquake engineering analysis.

Second, the impact of the massive earthquake on buildings in Japan was no greater than that of Taiwan’s 921 Earthquake. The impact on buildings is decided not by the magnitude of an earthquake, but by the intensity. In Tokyo, the intensity of the recent quake was level 5, so no serious damage was caused to buildings in Japan’s capital city. The intensity of the 921 Earthquake in some built-up areas was 7, and that is what caused many buildings to collapse. Although the Japanese earthquake was a shallow one, its hypocenter was still 32km deep, whereas that of the 921 Earthquake was just 1km beneath the surface. So, relatively speaking, the serious damage caused by the Japanese earthquake resulted from the tsunami, fires and radiation leaks, not direct earthquake damage to buildings.

Third, if we are to compare the ability of Japan and Taiwan’s nuclear power plants to withstand earthquakes, the comparison should be a rational one. It can be understood from what we have already said that the standard that determines the impact of an earthquake on a building should be the intensity of the quake. So the Japanese nuclear plant’s earthquake resistance of 8.5 cannot be directly compared against the figures of six to seven for those in Taiwan, because 8.5 refers to the magnitude of a quake, while the range of six to seven refers to intensity.

The fourth point is that soil liquefaction is an important destructive phenomenon associated with earthquakes, so we can’t afford to talk about it in vague terms. Soil liquefaction occurs when, during an earthquake, the moisture in saturated soil breaks down the soil’s particle structure, or when water is separated from the soil and wells up to the surface. This important aspect of earthquakes constitutes a hidden danger that is best left to specialists to explain.

The fifth and final point I wish to make is that Taiwan should improve the earthquake resistance of buildings used by the public. The government should also conduct more earthquake drills and improve everyone’s earthquake preparedness.

We can certainly learn from Japan’s experience in this respect. We also need to establish plans for responding to tsunamis and fires that often follow earthquakes, and for protecting nuclear power plants and coping with nuclear accidents.

The recent Japanese earthquake has indeed brought about a great calamity. We mourn for the victims and sympathize with those struggling to cope with the aftermath, but the most urgent task is to think about what we can learn from this disaster, and to prepare, seriously and based on accurate knowledge, for future disasters that can strike without warning at any time.

Jerry Huang is an architect and former chairman of the Taiwan Professional Environmental Engineers’ Association.