[SBS Kim Sung-joon's current affairs observatory]

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■ Broadcast: Kim Sung-joon's current affairs observatory (FM 103.5 MHz 14:20 ~ 16:00)
■ Progress: SBS Kim Sungjun anchor
■ Broadcast date and time: Monday, April 22, 2019
■ Talks: Professor Yoon-Soo Lee Professor, Department of Environmental Engineering, POSTECH

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- Uljin earthquake is not related to the Pohang earthquake.
- Donghae - Ulsan, located in the same fault zone ... Seems to be the reason for the earthquake.
- Energy dissipation on a small scale ... A big earthquake is preferable to what happens
- In 946 AD, the volcanic ash was only 1m thick
- Mt. Baekdu eruption, Hiroshima is like 160,000 bombs.
- Mt. Baekdu, a situation that is still in operation but can not be investigated
- Mt. Baekdu can be answered if it's safe.

▷ Kim Seong-joon / Host:

A magnitude 3.8 earthquake occurred at 5:45 am today (22nd) in the waters of Uljin, Gyeongbuk Province. Fortunately, it has been confirmed that there is no damage until now. Three days ago, there was an earthquake on the East Sea. Three days after the earthquake, the anxiety is growing. In addition, the possibility of eruption of Baekdusan nowadays comes up to this story, and it is a messy atmosphere. Professor Yoon Soo Professor, POSTECH Department of Environmental Engineering Professor Hello.

▶ Yoon Soo Lee Professor, Department of Environmental Engineering, POSTECH:

Yes. Hello.

▷ Kim Seong-joon / Host:

The result of the earthquake in Uljin today is 3.8. If it is the sea area and the scale is 3.8, how big should it be?

▶ Yoon Soo Lee Professor, Department of Environmental Engineering, POSTECH:

The earthquake happened in the sea area, and fortunately the earthquake occurred at a depth of about 21km. Indeed, energy does not reach the surface.

▷ Kim Seong-joon / Host:

It is 38 km from the coast and 21 km deep. If this happens in a deep place, regardless of scale, is it that you feel less of a strength?

▶ Yoon Soo Lee Professor, Department of Environmental Engineering, POSTECH:

Yes. That's right. Because it is attenuated.

▷ Kim Seong-joon / Host:

But this is "I am surprised to see the surprised chest and the lid of the pot." The last Pohang earthquake caused water to enter the ground for geothermal development. Did not these findings come out? Uljin and Pohang are not so close, but is there any possibility or possibility of this?

▶ Yoon Soo Lee Professor, Department of Environmental Engineering, POSTECH:

There is no possibility. The earthquake that created the earthquake crust structure including the Pohang area was that of Japan, originally attached to the peninsula. So, as it went off, the tension line created the structure line. It was an earthquake in that area. So the structure line is formed along the east coast of the Korean Peninsula. Therefore, it is called the Houpo fault zone or the eastern fault zone. The scale. So it is isolated from the fault zone on land. There is considerably less concern that it will affect the land.

▷ Kim Seong-joon / Host:

Even if the location is close, there is a different fault zone in the land and sea. That's it.

▶ Yoon Soo Lee Professor, Department of Environmental Engineering, POSTECH:

Because this is different from when it was created and the cause itself. The earthquake here can be done at the plate boundary if it affects the land. It is hard to expect in a place outside the boundaries of the plate like our country. So I would like to say that we should do that part, but do not worry so much.

▷ Kim Seong-joon / Host:

If you tell me that, I have no choice but to ask you another question. Three days ago, there was an earthquake in the eastern sea of ​​Gangwon Province. Then, as you said, earthquakes in the sea, both on land and at sea. Is not this a correlation?

▶ Yoon Soo Lee Professor, Department of Environmental Engineering, POSTECH:

It is interpreted that two are related to each other because they are in the same fault zone. And it's a region where the thickness of the crust in the area drops sharply. When the East Sea falls apart, the thinning of the crust and the thinning of the crust do not gradually become thinner, but they become very thin at certain boundaries. So it is called "mogeo" there, about 28km to 24km from the mantle. It decreases to such a degree. Therefore, the extent of the decline is that the crust on the surface is floating in the mantle. So, in a situation where the crust and the mantle are in unstable equilibrium, they have such stresses as the whole, acting on the east-west compressive force. It seems that this earthquake happened. It is the context of an earthquake that happened a few days ago.

▷ Kim Seong-joon / Host:

Then, what happened in the sea of ​​the East Sea in three days after this earthquake is not likely to be a precursor to a major earthquake in the near future?

▶ Yoon Soo Lee Professor, Department of Environmental Engineering, POSTECH:

It must be watched, but it's going to do a lot of damage for us to come up to the land. Yangsan Fault or Ulsan Fault. However, since it is different from the Yangsan Fault or the Ulsan Fault, the fact that it has such a direct influence is difficult because of its different character. So many people are worried about this earthquake. Conversely, energy does not disappear. So it is better to get up so often that the earthquake energy is reduced in such a small scale so that the big things do not happen in the future.

▷ Kim Seong-joon / Host:

It's easy to talk a little bit. Okay. But nowadays one of the worries about the earthquake is not the explosion of Baekdu Mountain. There are a lot of these stories coming out. We know that Mt. Baekdu was one of the records of the eruption in 1702 during the Korean War. Basically, is it the situation that we should worry about the explosion of Mt.
▶ Yoon Soo Lee Professor, Department of Environmental Engineering, POSTECH:

Mt. Paektu erupted in large scale in 946 AD. At that time, if the eruption scale is sprayed with volcanic ash in South Korea, the thickness is about 1m. Enough to cover South Korea. So it is the biggest volcanic eruption ever since, and I accept it all in academia. What is the energy, the 160,000 atomic bombs of Hiroshima burst out of Mount Baekdu?

▷ Kim Seong-joon / Host:

But is that something like that going to happen again?

▶ Yoon Soo Lee Professor, Department of Environmental Engineering, POSTECH:

The problem is, what is Baekdu Mountain now? The ideal of an active volcano is one of the few remaining volcanoes of massive volcanic activity, made from 23 million years ago, as if we are destined to die of all life forms. It is the largest among them. It has been active since tomorrow. If you do not do activities from tomorrow, then you can not see it. I have to keep doing activities. An active volcano erupts one day. The problem is what kind of situation we are now in the eruption of Mt. We do not even know what is happening in the magma of heaven and earth. So this is why it is okay for experts to ask questions to the people. If you ask me to answer that, I can assure you that it is definitely not right for the experts. Because, if 1/100 of 1/100 of the year of 946 is erupted, it is very serious situation.

▷ Kim Seong-joon / Host:

Yes. I'll listen to you here. thank you.

▶ Yoon Soo Lee Professor, Department of Environmental Engineering, POSTECH:

thank you.

▷ Kim Seong-joon / Host:

Yoon Soo I talked to Professor of Environmental Engineering at POSTECH.