The breath of the Earth

The earthquakes in Turkey in February 2023 became a really huge disaster causing a large-scale destruction with 49,000 deaths and 115,000 injured. Powerful nature showed its strength once again, and the echoes of the great disaster reached the Russian Black Sea coast and made many Sochi residents and guests of the city remember that the main Russian resort city is located in an earthquake-prone area. The EcoTourism Expert correspondent found out at the Sochi Seismic Station whether it is possible to predict a natural disaster, how to protect yourself from an earthquake and why scientists monitor the ‘breath of the Earth’. Despite the fact that this important organization has been operating for more than a century, few people know about its work. Seeing a nondescript white house facing a beautiful view, most people are very surprised that such a good piece of land has not yet been built up with high-rise buildings. “This is a federal property, the Seismic Station belongs to the Unified Geophysical Service of Russia,” explains Elena Karpovich, Head of the Sochi Seismic Station. By the way, she has been studying the earthquakes for almost a quarter of a century.

- First of all, how and where do earthquakes occur?

- Everyone remembers from the school geography lessons that the lithosphere consists of plates that move and overthrust. The seismic belts of the Earth - the places of the greatest seismic activity - are located in the places where the plates collide or move away from each other. One of these belts, the Pacific Ring of Fire, stretches along the perimeter of the most part of the oceanic area in Asia and North America, including California, Chile, Alaska, Kamchatka, Japan, Sakhalin-Kurils, the Solomon Islands, and New Zealand. Another important seismic area is the Alpine-Himalayan belt, which also includes the Caucasus Mountains. The earthquake of magnitude 8 can occur there. At the same time, the Sochi area accounts for 15 percent of earthquakes only, all the rest earthquakes occur in the area of the Pacific Ring of Fire.

Reference

The strongest earthquakes in the Sochi area:

1909 - an earthquake of magnitude 6 in the Krasnaya Polyana area.

1912 - an earthquake of magnitude 5-6 in the Shakhe River area.

1939 - an earthquake of magnitude 6 in the Lazarevsky District, Sochi.

1955 - an earthquake of magnitude 7-8. The strongest earthquake in Sochi occurred in the area of Krasnaya Polyana, without casualties, but the Krasnaya Polyana Hydroelectric Power Station was seriously damaged.

1970 - an earthquake of magnitude 5.1, with the epicenter in the sea near Loo. The earthquake shock was rather strong and the beach line from Loo to Vardane has expanded due to the rise of the coast.

1982 - an earthquake of magnitude 4 in the Central District of Sochi.

2012 - an earthquake of magnitude 5.7 with the epicenter in the Black Sea, 49 kilometers from Sukhum.

- Why was the Sochi seismic station set up and how does it work?

- Let’s start with the fact that in 1927, a major earthquake was recorded in the Crimea, it was even described by writers Ilf and Petrov in their famous book “The Twelve Chairs”. The task was set in the country to study the seismic activity of the Black Sea coast. In 1929, the first nonstationary stations appeared in Sochi, and a fixed one began to work in 1932. In those years, it was located in the Riviera Park, but the resort city expanded, and in 1963, the seismic station was moved to Bytkha, a not densely populated area at that time. This was done to minimize the possible interference during measurements as the seismometers recording the vibrations of the earth’s crust are very sensitive. Similar stations were set up in many earthquake-prone cities of the country. Today, our seismic station is included in the southern project, similar ones operate in Makhachkala, Anapa, and Kislovodsk. In addition to the fixed station, we have nonstationary ones in various districts of Sochi, for example, in the Lazarevsky District, Adler, and in Krasnaya Polyana. And there are also stations in Agoy and Guzeripl.

- What measurements do you make, how do seismometers work?

- Seismometers measure the vibrations of the earth’s crust. They are installed in a separate pavilion, that is why our station has a large area of 0.67 hectares. The seismometers are installed on concrete pedestals, which are tightly fixed with bedrock. There is a small distance between the concrete pedestals and the floor, which avoids contact and minimizes unnecessary vibrations. The seismometers record three types of vibrations - vertical ones and two horizontal ones - from north to south and from west to east. Until the 2000s, seismometers were analog. The measurements were recorded on a special photographic paper with a thin light beam. If there were shocks of earthquake, an audio alarm sounded at the seismic station, it was necessary to take such a film and develop it in a dark room, then decipher it. In 2002, the Sochi Seismic Station became ‘digital’. Now, data from seismometers are transmitted over the Internet. We see a graph looking like a patient’s cardiogram. From these graphs, we can determine the magnitude of the shocks, the earthquake’s epicenter. Now, we have seismometers made in the USA. They look just like small jars.

- What distances do the seismometers cover?

- Our station, like all other ones in the world, records all the earthquakes that occur in the world. To make it clearer, imagine that you throw a stone into the water and you see a ripple effect. The stronger the blow, the more waves are around and the longer distance of the wave propagation is. So, the situation is similar during an earthquake. If an earthquake, for example, occurs in the USA, but it is very strong, the vibrations reach Sochi, and our seismometers record them. Therefore, we divide the data received from the devices into three levels. Teleseismic refers to earthquakes that occur all over the world. If the shocks of earthquake are comparable in strength to the Fukushima ones, our seismometers can record them. Regional measurements are made at the distances from 200 to 2,000 kilometers. For example, when there was an earthquake in Turkey, its shocks reached Sochi and our seismometers recorded them, especially during the second shock that was stronger. To measure the strength of earthquakes, a special notion - magnitude - is used. For some reason, everyone describes it in ‘points’, although in fact, it is some empirical value, which is calculated from the difference in amplitude indicators in arbitrary units, an energy burst at the epicenter. And ‘points’ show the earthquake intensity, that is, how the earthquake is felt in different places. So, magnitude of earthquake in Turkey was from 7 to 8, and in the Sochi region, the earthquake intensity was from two to three points. Most people do not even feel such small earthquakes, but instruments record them. The third level of shocks of earthquake that the station detects is local - in an area up to 220 kilometers, for example, in the Sochi’s Lazarevsky District. The result is a kind of three-level ‘control’ of earthquakes. All data from seismic stations located all over the country are transmitted to Obninsk, where the main Center of the Geophysical Survey of the Russian Academy of Sciences is located. They are used for various scientific research projects.

- How often do earthquakes occur in the Sochi area?

- We don’t have such statistics. On average, probably once or twice a month. For the most part, earthquakes are recorded in our region, which are practically not felt, many people do not even realize that they live in a higher seismicity area. At the same time, such earthquakes can even be called ‘useful’, a kind of discharge of energy that accumulates during the movement of tectonic plates. These earthquakes allow the energy to come out and it doesn’t accumulate as its accumulation can lead to major disasters. Imagine a pot with boiling water. If you open the lid a little, the steam comes out and everything is in order. But if the lid is tightly closed, it can be just blown off due to the pressure growing inside. Therefore, we do not even report small earthquakes to avoid panic.

- What earthquake intensity do people start feeling?

- It depends, of course. It depends on what floor the person is, whether the person is standing or sitting. But, starting from the earthquake intensity of 3, you can already feel the “breath of the Earth”. There is a special memo describing the consequences of earthquakes depending on their intensity. In 2012, there were several earthquakes in Sochi with an intensity of more than 5. I was sitting at the computer at that moment and my chair moved away from the table. For example, when the intensity is 7, hanging objects are swinging strongly, furniture is moving, books are falling. When the earthquake intensity is 9 and higher - such earthquakes are called ‘catastrophic’ ones - the furniture overturns, breaks, significant damage occurs in many houses, some houses are destroyed, cracks in the soil appear, existing water springs disappear and new ones appear.

- I would like to ask a question that many people have. Can an earthquake be predicted?

- Scientists have been working on predicting the earthquakes for a long time, but an earthquake cannot be predicted yet. Many people say that some Norwegian scientist warned about an earthquake in Turkey. But the fact is that Turkey is part of the seismic belt, it is natural that an earthquake can occur there some time. So far, no one can say for sure that in a certain place, on a certain date an earthquake of certain magnitude will occur. For example, there is an assumption that an earthquake precursor may be a change in the groundwater level or the amount of radon. My father who was also a seismologist worked on Sakhalin at the laboratory of earthquake precursors and studied such phenomena. Similar scientific research projects have been going on for many years, but so far, scientists still cannot predict earthquakes.

- If it is impossible to predict an earthquake, can people somehow protect themselves?

- First of all, it is a question of earthquake-resistant construction. The earthquake in Turkey showed that huge destruction and casualties could have been avoided if all the construction standards and building codes had been observed. One may ask, what about the earthquake in Japan, at Fukushima? The Japanese seem to be constructing very high-quality buildings, they have developed technologies for creating earthquake-resistant buildings. Thanks to such high-quality earthquake-resistant constructions, many objects survived there during that strong earthquake, and even during a tsunami. If the nuclear power plant had collapsed, it would be a global catastrophe. In general, I think that specialists constructing buildings in earthquake-prone areas should bear some kind of personal responsibility. You know, a designer of an automobile bridge stands under it when the bridge is being commissioned and auto vehicles start moving, he shows that he guarantees its strength and safety. In the Soviet times, the construction industry was supported at the state level by many construction design institutes that studied the regions and calculated the stability of structures. Now, unfortunately, this is not the case. Designers often reduce the seismicity level to lower the construction project cost. Of course, not a single private organization will be able to maintain such construction design institutes that worked in the Soviet days and a state initiative is required.

- How to behave in case of an earthquake? What to do, where to run? Someone advises hiding in the bathroom ...

- First of all, don’t panic. The most powerful shocks last for just several seconds not minutes. If you’re in a building, it’s best to stand near an internal load-bearing wall so that if the external beams start to collapse, you won’t be outside. You can hide under the table. Why is it advised to be in a bathroom? You can have an access to at least some water. Because rescue works begin after the active phase and possible destruction, and a person needs to survive until the rescuers find him or her. In Turkey, people were found under the ruins even after seven days, which means they had some minimal quantity of water.

If you are on the street, try to run out to an open place so that nothing could fall on you. Do not stand under wires that can break. But most importantly, don’t panic.

Can a tsunami occur in Sochi? Professor of Sochi State University Konstantin Makarov answered this question.

Tsunami waves can occur in completely calm weather due to earthquake shocks in the sea. Recently, a new set of rules for tsunami-prone areas has been published in Russia. Earlier, it included such areas like the Kuril Islands, the south of Kamchatka, Sakhalin where the wave can be two or three meters high and have a destructive power; and now, the Black Sea, Anapa and the Lazarevsky District of Sochi were included in the list of tsunami-prone areas. Once every 1000 years, the estimated height of waves approaching the coast in these areas can reach 0.5 meters. Tsunami waves up to one meter high are not very dangerous. But if such waves enter from the sea into a narrow structure, they can concentrate. This must be taken into account when creating marinas and making other structures.