Taipei Times: Tragic landslides like the ones that hit National Highway No. 3 [Formosa Freeway] and the Suhua Highway this year keep happening. Is something going wrong with the land in Taiwan that brings floods and landslides every time it rains?
Hongey Chen (陳宏宇): Taiwan’s geology is very young and very active. The Pacific and Philippine plates often collide, so earthquakes are frequent. There are eight or nine tremors every day in Hualien. The Central Weather Bureau often describes them as normal releases of energy, but that doesn’t mean we should take them lightly, because this is Taiwan’s fate. Taiwan’s environment is fragile. It sits on the Pacific Ring of Fire, so it has a lot of earthquakes. The earth’s crust is a rigid rocky structure. Collisions and compression in the crust cause cracks and fractures. When rainwater penetrates cracks in the rock, it creates water pressure that can cause rockfalls and even landslides.
Besides, Taiwan’s geological structure is mostly sedimentary rock and it is a country with many cataclinal slopes. Most textbooks published in Japan and other countries say that landslides usually occur where there are slopes whose gradient is 25o or more, but Taiwan is an exception to this rule. The landslide that swept across National Highway No. 3 involved a mountain slope whose gradient was just 16o. In the case of the Caoling (草嶺) landslide [triggered by the 921 Earthquake in 1999], eight collapses brought 130 million cubic meters of rock and soil crashing down, but the gradient was just 12o. All of these are cases of cataclinal slopes, which means that underground geological strata run parallel to the surface. It is also Taiwan’s fate to have these special geological conditions.
PHOTO: FANG PIN-CHAO, TAIPEI TIMES
Of greater concern is that the climate is becoming more extreme. Meteorologists often say that Taiwan has four or five typhoons a year on average, but typhoons are unpredictable. Rainfall is getting more extreme and more unevenly distributed. During Typhoon Fanapi, more than 600mm of rain fell over some urban areas of Kaohsiung and Pingtung in a single day — the kind of downpour one would only expect to see once every 200 years. Now Yilan and Suao (蘇澳) have experienced the heaviest rainfall in one day in recorded history under the combined influence of Typhoon Megi and the northeast monsoon.
With such a fragile geological environment, combined with the external factor of the worsening climate, disasters keep occurring in Taiwan. Not just in the mountains — they happen in cities, too. Time and again, they remind us that you have to be very careful where the terrain is so susceptible. It’s just like when a doctor tells you that your constitution is weak, so you have to be careful about your daily living habits. That means that a lot of land development in Taiwan needs to be cut back and we have to be more careful about construction. For example, National Highway No. 3 cuts through the base of rocky slopes, so the rock anchors and soil nails used to stabilize the slopes need to be thicker and bigger. As for Yilan and Kaohsiung, they both have -drainage problems in urban areas. Drainage volume must be made bigger than the empirical values of past construction. Then there is the question of whether people can live in low-lying areas. How much land needs to be set aside to dig flood detention ponds to contain however much rain may fall over the next century? Furthermore, we need to do a proper job of water and soil conservation. It is even more important to set up a proper monitoring system. We can’t take the conventional view of construction that once something’s built, it’s safe. The warning signs have been there for a long time — it’s just that the government and public do not seem to have paid proper attention to them. A monitoring system has to be put in place and the government should tell people where the terrain is susceptible. Is 50mm of rainfall the right standard for closing roads? All these things need to be carefully thought over.
TT: The Suhua Highway landslide has once more brought attention to the necessity of building alternate routes along that stretch. The issue is even threatening to break out into political controversy. Premier Wu Den-yih (吳敦義) has already pledged that the project will pass its environmental impact assessment (EIA) and he wants construction to start by the end of the year. What do you think of the idea of improving sections of the Suhua Highway?
Photo courtesy of the Central Emergency Operation Center
Chen: The Suhua improvement plan, involving alternate routes along several sections of the highway, and the Suhua Highway itself are two separate matters that will fulfill specific functions and should therefore be dealt with differently. People along the east coast between Hualien and Taitung have long been calling for “a safe way to get home,” which of course everyone can understand and sympathize with. But there are other things to consider. If you live in Hualien and it’s simply a case of traveling along that stretch of road through pitch-dark tunnels to get from A to B, that’s not really a problem. The problem is that the existing highway is also used for tourism. Tourists aren’t going to want to go through these same tunnels in complete darkness. Hualien is famous for its cliff faces and steep ravines, but they won’t be able to see them. That’s going to really hurt the tourism industry. Tour operators and local governments alike will be hopping mad.
The Ministry of Transport and Communications [MOTC] has resolved to keep the Suhua Highway in operation whatever happens and I’m afraid that tour buses are still going to drive along the highway. It’s not like the danger is going to disappear. It doesn’t matter how pretty the scenery is, it’s still dangerous. Both routes will be in operation at once. So, which one are the tourist buses going to use? The direct route home and the scenic route are different things and involve different considerations. One thing is certain, though. They both need to be subjected to more detailed geological surveys and the highest possible standards should be applied in the interests of public safety.
The reconstruction proposals look simpler than the original Suhua Highway project, but there are still geological complications. I’m afraid the MOTC might have been a little ambitious when it claimed that the project was going to be simpler than the tunnel construction in the area around Yushan (玉山). According to the geological survey, the improvement project will involve going through at least eleven fault lines, including the Siaomaoshan (小帽山) fault and the Houyishan (猴椅山) fault, and those are just the ones we know about. There are sure to be more than what were encountered during the Yushan -tunnel project. Geologists have been pointing out for some time that the Yushan project had to cut through relatively conventional folded strata — far more conventional than the folded strata the Suhua improvement project is going to have to pass through. These strata are more contorted, shattered, often truncated by fault lines, and in many places engineers are going to have to deal with complex geology including synclines and anticlines. I just don’t think the transportation authorities know what they’re getting themselves into.
The government has said that the Suhua improvement project is to pass its EIA this month and be completed by 2016, suggesting it’s going to take at least six-and-a-half years to complete the project, squeezed into a tight 2016 deadline. Remember that in the case of the Yushan tunnel they said it would be done in six or seven years, but in the end it took 15 years to complete. It’s not impossible to overcome the challenges presented by complex, sensitive geology. Engineering techniques can always be adjusted, but this does require detailed surveys to be undertaken. You can’t just say that an undertaking of this kind will be done in so-and-so many years. It just doesn’t work like that.
For the sake of the Hualien and Taitung regions, no one, including environmental groups, is against the Suhua Highway -improvement plan per se, but there really haven’t been enough geological surveys done. Some scholars are concerned that a lot of the statistics come from data provided by the Taiwan Railways Administration [TRA] from its experience on the North-Link Line, but this fails to take into account the considerable geological shifts and changes that happen in mountainous areas. Are the transportation authorities really ready for this project? It’s not enough to rely on outside figures. They should conduct their own internal, detailed surveys. Another thing is, how much do the EIA experts know about the actual geological conditions? One cannot afford to be too frivolous with the EIA and there’s no reason to rush into starting the project or getting it done.
TT: Taiwan’s geology is young and subject to many changes. It is also complicated and sensitive. What suggestions do you have for preventing disasters and improving things?
Chen: After Siaolin Village (小林) in Kaohsiung County was wiped out by a mudslide [during Typhoon Morakot in August last year], the government asked me to carry out an investigation into 185 mountain areas in central and southern Taiwan. I discovered that 115 villages were not safe, which was 62 percent of the total. As soon as my findings were released, residents of these areas protested the findings, saying that they were going to be forced to leave their homes where they had lived for decades. -However, the -recent Typhoon Fanapi and Typhoon Megi saw the government evacuate people from more than 200 villages. Some ask whether this was too much. My answer to this is no, because it was done out of safety and so it was the right thing to do.
We gain experience from every loss of human life. Every time disaster strikes, we learn a new lesson.
Just at the time of the Suhua Highway landslide, researchers from an Italian disaster prevention research institute happened to be visiting Taiwan. They expressed worries about the sensitive nature of the geology the highway sits on. They asked why the Taiwanese government didn’t warn tourists of the dangers beforehand. Why do we have to wait for legislation before authorities will protect people’s lives by warning them about the dangers of geologically vulnerable areas? The government has a responsibility to do such things at all times.
Disaster prevention and relief cannot bow to emotional or political pressure. Wisdom and resolve are needed. Mother Nature has given Taiwan many lessons and opportunities.
How should people in Taiwan go about cherishing their own lives and building truly safe homes? I am sure many people have known the answer to this question for some time.
Now everything depends on when people will make up their minds to do what is necessary.
Tropical depression TD22, which was over waters south of the Ryukyu Islands, is likely to develop into a tropical storm by this morning and pose a significant threat to Taiwan next week, the Central Weather Administration (CWA) said yesterday. The depression is likely to strengthen into a tropical storm named Krathon as it moves south and then veers north toward waters off Taiwan’s eastern coast, CWA forecaster Hsu Chung-yi (徐仲毅) said. Given the favorable environmental conditions for its development, TD22’s intensity would reach at least typhoon levels, Hsu said. As of 2pm yesterday, the tropical depression was about 610km east-southeast of Taiwan proper’s
Four factors led to the declaration of a typhoon day and the cancelation of classes yesterday, Taipei Mayor Chiang Wan-an (蔣萬安) said. Work and classes were canceled across Taiwan yesterday as Typhoon Krathon was forecast to make landfall in the southern part of the country. However, northern Taiwan had only heavy winds during the day and rain in the evening, leading some to criticize the cancelation. Speaking at a Taipei City Council meeting yesterday, Chiang said the decision was made due to the possibility of landslides and other problems in mountainous areas, the need to avoid a potentially dangerous commute for those
Typhoon Krathon, a military airshow and rehearsals for Double Ten National Day celebrations might disrupt flights at Taiwan Taoyuan International Airport in the first 10 days of next month, the airport’s operator said yesterday. Taoyuan International Airport Corp said in a statement that it has established a response center after the Central Weather Administration issued a sea warning for Krathon, and urged passengers to remain alert to the possibility of disruptions caused by the storm in the coming days. Flight schedules might also change while the air force conducts rehearsals and holds a final airshow for Double Ten National Day, it added. Although
SEMICONDUCTORS: TSMC is able to produce 2-nanometer chips and mass production is expected to be launched by next year, the company said In leading-edge semiconductor manufacturing China is behind Taiwan Semiconductor Manufacturing Co (TSMC) by at least 10 years as the Taiwanese chipmaker’s manufacturing process has progressed to 2 nanometers, National Science and Technology Council (NSTC) Minister Wu Cheng-wen (吳誠文) said yesterday. Wu made the remarks during a meeting of the Legislative Yuan’s Education and Culture Committee when asked by Democratic Progressive Party Legislator Wu Pei-yi (吳沛憶) about a report published in August by the Chinese version of Nikkei Asia that said Taiwan’s lead over China in chip manufacturing was only three years. She asked Wu Cheng-wen if the report was an accurate
RSS