When we hear the word, 'Japan', 'Earthquake' is the first word that calls to remembrance. Japan is a nation where earthquakes occur so much that it is called the 'nation of earthquakes' as its nickname. On the other hand, Korea is regarded as safe from earthquakes since Korea is away from the seismic source zone. But last December, an earthquake occurred in Iksan, Jeollabuk-do province and Geumsan, Chungcheongnam-do province and some places in Seoul could feel it, too. So, Korea is not a safe place from earthquakes any longer. But like the proverb, 'Know the enemy and know yourself; in a hundred battles you will never be in peril'; even though you know about earthquakes, you can't beat it. But you can at least minimize the damage. So let's find out about the enemy that gives us pain.
1. What is an earthquake?
Under the definition of earthquake in the dictionary, it is defined as a; 'Shaking of the earths crust while deformation energy, which accumulated for long time, is released'.
'Elastic rebound theory' shows how earthquakes occur. To clarify, when we curve both ends of a sausage, because of elasticity, it bends easily, but when we continuously bend it, it breaks and the bent part becomes straight.
In the same way, when the crust receives force it also bends and changes its shape. When the force accumulates and the crust can't endure it, the crust breaks and becomes a fault. Then by repulsive power, which is the force of going back to the original form, the earthquake occurs. The ‘epicenter' is where the energy occurs, which is the point and cause of the earthquake, and 'theseismiccenter' is the point on the surface of the earth, vertically connected to the 'epicenter'. As ‘theseismiccenter’ is the closest point to the 'epicenter', it gets the most damage. So, countries like Japan, where many big earthquakes occur, is located near 'theseismiccenter'. This area is called the 'circum pacific volcanic belt' or the ‘Ring of fire’, and it is where one of the world's major earthquake zones and volcano zones overlap. Even though Korea doesn't belong to the 'circum pacific volcanic belt', more than ten small-sized earthquakes are reported here each year.
2. Can we predict an earthquake?
1) 'Prediction' by professionals
In April 2015, a 7.8-sized earthquake occurred in Nepal. Due to this earthquake, at least 8000 people died and 16,000 people were injured including some Korean people. Would you believe somebody who predicted this earthquake 6 years before it happened? In fact, an English researcher predicted it 6 years ago, when an earthquake occurred in Italy, that the next big earthquake would be 8.0 on the Richter scale and occur in Nepal. In relatively quick succession, 3 years ago a French researcher predicted very big earthquake would occur in Napal and a month before the earthquake occurred, Laurent Bollinger, who works in the CEA-laboratory, precisely predicted the point where the earthquake would occur. How could they predict the earthquake? According to specialists who predict earthquakes, Nepal is part of the Indian Plate from the south that is collapsed under the Eurasian Plate. Normally it burrows 4cm each year but recent research on this area indicated that movement had stopped for hundreds of years. So, April 2015 was the point right before it broke, and when the accumulated energy was maximized.
Like the specialists who predicted earthquakes in Nepal, we call this a 'prediction'. Since it is just a 'prediction', we can't be certain of a specific date for the earthquake.
2) 'Instinct' of animals
Normally, when an earthquake is over 3.0, some people can feel it inside. But when it comes to quakes that are less than 2.9, only a sseismometer can detect it. However animals, which are sensitive to outer change, can predict natural disasters like earthquake.
We can find some evidence through two cases in China and Japan. First, in China in 2008, before the big earthquake in Sichuan, hundreds of thousands of toads took over a road. Also, in 2015, on the east coast of Japan, 10 days a 6.8 earthquake occurred in the adjacent seas of Okinawa, 160 dead dolphins were found.
Researchers are still working on it, but since there is no scientific evidence of animals feeling earthquakes, we can’t conclude that animals can predict earthquakes.
3) Earthquake clouds
In March 2015, an MBC program called ‘Mystic TV: Surprise’ talked about predicting earthquakes through ‘Earthquake clouds’. The content from a daily newspaper in Japan in 2005, wrote about a Japanese who predicted an earthquake, and then 10 days later a 6.1 earthquake really happened. The person who predicted this earthquake was ‘Sasaki Heroharo’, who represents an association for predicting earthquakes in Japan. He predicted the earthquake by observing electromagnetic waves that affect the shape of clouds when earthquakes occur. But some seismologists refuted his theory. Since clouds are made as moisture rises and the vapor congeals and becomes tiny droplets. Also some specialists denied his theory because it is based on too few examples.
But last May 2008, a Chinese boy uploaded a picture on the Internet of uniquely shaped clouds. 7 days after he uploaded the picture, a big earthquake occurred in Sichuan. And recently, in Korea, earthquake clouds occurred. According to the notice that a student, living in Busan, uploaded on the Internet in December 2015, he was worried that an earthquake would soon occur. His writing became popular after a 3.9 earthquake occurred in Iksan-si, Jeonbuk 2 weeks after he uploaded the writing.
But even with these examples, the academic world sticks to the stance that it is probably only coincidence and too much to ask to include 'earthquake clouds' in the earthquake predicting system.
3. Instance of Earthquake occurred in Korea
According to historical records, we can see that many earthquakes have occurred in the Korean Peninsula. At least 40 of them are estimated as big earthquake and show records of damages to property and life.
As noted in a report by the meteorological observatory of the Government of Korea from 1905 to 1942, according to instrumental earthquake data, earthquakes were reported in the Korean Peninsula and nearby sea 553 times, or 14 times each year during that 38 year period. Since there are few seismological observatories, the number observations of earthquakes may also be low. It is thought that the number of middle-sized earthquakes is bigger than has generally been observed.
Relatively accurate observations have been recorded since the Meteorological Administration started to observe earthquakes in 1978. Since 1978, the biggest earthquake was in Songnisan on September 16, 1978 and on the coast of Uljin on May 29, 2004. Since 2015, on the south side of Korea, 3.9 sized earthquakes have occurred continually. It means, since more than sized 3.0 earthquakes are consistently occurring, Korea is not a safe place from earthquakes anymore.
4. How do earthquake hotspots normally prepare for earthquakes?
Japan is one of the top earthquake hotspots. Japan offers earthquake preparedness training several times a year and does earthquake safety drills three times a year. Of course, our country also does earthquake safety drills once a year but they are sloppy because they don’t consider that there is much earthquake danger. On the other hand, when Japan conducts a drill, they do not go out simply but actively to protect their body.
Also Japan operates earthquake experience centers. Our country also has a Civil Disaster Training Center but that is only located in Seoul so it is difficult for all Korean people to join, and there’s a limitation of from 5 to 7 people. On the other hand, Japan has that center in many places to teach caution regardless of age and nationality. For a close look at this, they show the Japan earthquake video before experiencing earthquake, they teach about the cause of the earthquake. Next the experience centers teach how to evacuate when you feel the earthquake and what to do about the secondary shock.
Finally, Japan is a representative state for earthquake resistant designed buildings. These building requirements are meant to make structures more resistant to an earthquake. Japan has earthquakes a lot, so they instituted this a long time ago, but our country is only instituting this in a few new public buildings in Seoul.
5. What our country must do to prepare for earthquake damage
First, we have to use earthquake resistant designs in all spaces to prevent earthquake damage. The reasons given for not doing reinforcement work is not only the enormous expense but considered invalid compared to the case of Japan. Also our country doesn’t have a compulsory provision for earthquake resistant design, so it is difficult to administer. All Japanese people recognize the danger of earthquakes so general owners are active about earthquake resistant design. Koreans don’t recognize earthquake danger so we don’t do that. Although maybe not as urgent as in Japan, we still have to prepare for the introduction of earthquake design to minimize the damage.
Earthquake safety drills should be done for all ages. When an earthquake occurs, the damage is not just to elementary students but for all people. The training methods would be changed. When drill is announced, we should not go out casually but need to be drilled using media such as videos about why the earthquake is dangerous and how to cope with the secondary shock.
Finally, one of the most important things is people’s interest in earthquakes. Even if our country works on earthquake prevention, it’s ineffective if it doesn’t have public interest and support. Of course our country has difficulty feeling the danger of earthquakes because our country’s earthquake size is small compared to earthquake hotspots Nevertheless, we need insurance against danger in advance.
On 16 April 2014 the Sewol ferry accident took many young and delicate students’ whose only care was about going on a field trip. The cause of the accident was ‘nonfulfillment to perform safety checks’. On 20 May 2015 a man returned from his business trip in the Middle East after being infected with MERS. The cause of the illness that could have been eradicated early but instead spread quickly killing many people was also due to ‘Poor isolation and prevention’. As such, many people lost their life because we took no notion of ‘safety’. There’s a saying; ‘You can never be too careful’. That is, our caution is never too much. Our country already knows that we must be cautious after the Sewol ferry sinking and MERS. Let’s not be so shallow as to think that our country is safe from earthquakes, rather we need to avoid more damage and prepare now to minimize earthquake damage. < Copyright © The Gachon Herald All rights reserved >