A series of earthquakes in China, Kyrgyzstan and Kazakhstan may provoke tremors in Russia, but their strength will be significantly reduced due to the remoteness of the source of seismic activity. The head of the seismic hazard laboratory at the Institute of Physics of the Earth named after V.I. told RTVI about this. O.Yu. Schmidt RAS, Doctor of Physical and Mathematical Sciences Alexey Zavyalov.
A powerful earthquake occurred on the border of China and Kazakhstan. What is known
Is there a risk of an earthquake increasing in area?
Earthquakes of this magnitude – estimated at magnitude 7.3 – don’t happen every day. Even on our planet, over more than 100 years of seismic statistics, such earthquakes occur approximately one to one and a half times a month. This is quite a rare event. The area of seismic activity in this region of Central Asia is quite wide – it includes the territory of China, Kyrgyzstan, Kazakhstan, Uzbekistan, and Tajikistan. Where else can he expand? Moreover, it goes lower to the south through the territory of China, overlooks the Himalayas, and the Himalayas are an earthquake-prone area, and further – all the way to the southern Chinese province of Yunnan with its capital in Kunming, where there are quite strong earthquakes. To the west of the Chinese border are India and Nepal. These are also seismically active areas.
Where is the greatest risk of destruction?
The risk of destruction does not simply mean the occurrence of earthquakes in these areas. The risk of destruction depends very much on the quality of construction. There is a saying in the seismological community, which can be found in an article by one of our famous seismologists, who, unfortunately, has already passed away, that it is not an earthquake that kills people, but buildings.
If you find yourself in an open area and a strong earthquake occurs, yes, you will not be able to stand on your feet, but you will not die, because there are no collapsing buildings around. If, at the time of a strong earthquake, you find yourself in a building that is also poorly built, of poor quality in terms of its structural stability, then the building will naturally collapse and bury you under its rubble.
Will the earthquake provoke seismic tremors on Russian territory?
Theoretically this is possible. Moreover, I will say that not only a strong earthquake, but also any earthquake that occurs in one way or another affects the occurrence of subsequent seismic events. Only the degree of this influence depends, firstly, on the magnitude of the seismic event that occurred, and, secondly, on the distance [между эпицентром землетрясения и той территорией]where we expect subsequent shocks to occur.
That is, the further you go, the stronger the impact of the earthquake that occurs decreases. Most likely – with the square of the distance. Therefore, we can hardly expect significant changes in the seismic regime in our country due to the strong earthquake that occurred in China.
How long can an earthquake last?
In seismology there is the concept of a “seismic cycle” – when an earthquake occurs with some periodicity in the same place. But this, again, is a statistical rule. Since a strong earthquake occurs quite rarely in the same place, the scatter in this return period is quite high.
Therefore, I would say that after such a strong event, in the coming years, seismic activity here will be at the normal background level. What pushes me to this conclusion is that after the main shock, after the strongest earthquake, about two dozen aftershocks, which we call “aftershocks,” have already occurred. When aftershocks occur, this indicates that the tectonic stress accumulated in this place is being discharged, and the stress level in this place decreases.
But it decreases in this particular place. Each earthquake that occurs transfers stress to neighboring areas. It’s like dominoes when the dominoes are pushed and they start falling one after another. But specifically in this place, the size of the focal area of the earthquake that occurred is, roughly speaking, about a hundred kilometers. And the stresses that were realized in this source were collected, according to rough estimates, from an area an order of magnitude larger than 100 kilometers.
Accordingly, somewhere within a radius of 500 kilometers from a strong earthquake that occurred in the coming years, the level of tectonic stress will most likely be reduced, and seismic activity will simply occur in the background. It will not disappear completely, but mostly moderate earthquakes will prevail.
