— Alexey Dmitrievich, many scientists today are trying to make predictions about upcoming earthquakes. For example, geophysicists from the University of Southern California analyzed the seismic fault that caused the February earthquakes in Turkey. As a result, they concluded that an earthquake would soon occur near the Pyturge region in eastern Turkey. What do you think of this prediction?
– Until I see the analysis materials, this will be a false statement to me. If I see them, first of all, I will need to understand what the history of the predictions based on this data is, what the forerunner of a seismic event looks like, and other details.
American colleagues reported that they observed abnormal seismic activity in the area. Then they conclude: “We believe another strong earthquake is preparing here.” In addition, they indicate its size – 6.8. Again, the question is on what data the size estimate is made. I looked at the data on ongoing earthquakes and didn’t see any anomalous seismic activity in the Pyuturge area, nothing. Even in the neighborhood with a radius of 100 km, there is nothing.
Regarding earthquake predictions and failures: In the mid-1970s and 1980s, the Parkfield experiment was conducted in the USA on the San Andreas Fault in Southern California. There is a place called Parkfield, and previous observations of this part of the San Andreas Fault have shown strong earthquakes to occur here as planned, and this has been repeated several times.
Scientists calculated what year the next shock would be, placed the equipment there and waited. But nature turned out to be much more cunning: the expected earthquake did not happen when expected. Moreover, it occurred in a completely different part of the fault.
— The predictions of Frank Hougerbits, a Dutch seismologist, were also popular. The last one: The Far East is threatened by a mega earthquake in late spring. How do you evaluate the estimation technique?
Calculates the probability of an earthquake from the positions of the planets. If the planets are ascending in a certain way, then an earthquake must occur. In this case, I would also like to know what the retrospective statistics of their positive predictions are, then it will be possible to judge whether the technique is working or not. In general, Hugerbits is more of an astrologer, and the media presented him as a Dutch seismologist. No, he is not a seismologist.
Like so many times in my life, I think nothing will happen. Many times I have come across such guesses … and nothing! Then, as a rule, the authors of these predictions completely disappeared, they were never mentioned again.
— That is, earthquakes from planets are unpredictable?
– It’s hard to say for sure.
Of course, the processes taking place on Earth are also affected by cosmic forces. The only question is the size of this effect. For example, the Moon affects the tides of the sea. Moreover, the same type of tides occur on the earth’s surface, in the firmament. These tides have a certain amplitude: a few millimeters, centimeters.
In fact, the influence of lunar tides on the formation of strong earthquakes can be assumed, since the Moon is closer to Earth than, for example, Mars, Mercury, Neptune, Jupiter and other planets. Their influence is much weaker than that of the Moon, but for some reason the Hoogerbits focus on them.
– There was also such a prediction: the increase in seismic activity in Romania will cause a series of earthquakes in the Crimea during the summer. Is this possible?
– Yes, but with a caveat: in the Crimea, only the repercussions of earthquakes in Romania can be felt, and not such earthquakes. In general, Romania earthquakes occur in both Moscow and St. It can be felt in Petersburg. Although Crimea is one of the seismically active regions of Russia, quite severe earthquakes have occurred here.
If there is a strong earthquake in Romania, which I do not exclude, the waves from it will scatter far away and in the Crimea they will certainly feel its repercussions, but there will be no destruction, they will reach a maximum of 3-4 points.
There is a good example: in May 2013 there was a strong earthquake with a magnitude of just over 8 in the Sea of Okhotsk at a depth of 600 km (no need to add “dots” after the term “magnitude”! This is a big mistake!) And its repercussions reached Moscow. Many Muscovites felt them.
— Your colleague Alexey Lyubushin also proposed his own earthquake forecasting method. It focuses on seismic noise. What do you think of this kind of prediction?
— Despite the fact that Alexei Alexandrovich is my colleague, I am skeptical about these estimates. His prediction was correct for the Great Japan Earthquake (Tōhoku Earthquake) of March 11, 2011. But this is the only case and many predictions have already been made. Now on to the next prediction. I think this will end with nothing.
Here the problem is different. Alexey Alexandrovich is a great expert in processing and analyzing long-term observation sequences. He does this analysis professionally, but then comes the interpretation of the results. A fortune teller speaks like this and if someone else sits next to him, he will say it in his own words. This is what is called interpretation, and my view on it differs from Lyubushin’s.
– Which methods do you think are the most accurate?
– A lot of work is being done to examine the patterns of the physical process before an earthquake occurs. These patterns sometimes work, sometimes they don’t.
Scientists make predictions to gather statistics. A good example is weather forecasts. They’re also not always accurate, but get more accurate over time. So far seismologists don’t have it either, we don’t know well enough how the earth’s crust is arranged.
– What are these models?
These are called earthquake harbingers. There are about 600 in total, but none of them gives a 100% guarantee that a strong earthquake will come after the appearance of a harbinger. Even if you use a set of messengers, this set does not always work. Sometimes it works and more often it doesn’t.
I can count the most frequent messengers, so to speak. For example, in the region of a strong future earthquake, a seismic lull appears some time before it occurs: either the seismicity decreases completely or disappears within a certain magnitude range.
Such a recession can either persist until a strong earthquake occurs or be replaced by seismic activity in the area. Such a successive change of calm and activation is one of the harbingers.
Second, in a future strong earthquake zone, a swarm of weak earthquakes occurs suddenly, with epicenters close together in both space and time.
The third herald is a change in the chemical composition of groundwater. We can fix this if wells are drilled and samples are taken in a seismically active area.
In some places deformation measurements are made – the distance between two points on the earth’s surface. Before a strong shock, the slopes of the earth’s surface sometimes change regularly. There are also precursors observed in the ionosphere, in the atmosphere, for example, in unusual glows.
— Do you have your own method for predicting earthquakes?
– Sure, but I’m not the only author of this method. Perhaps the main performer is me, but my ideologue friend and teacher Gennady Aleksandrovich Sobolev, Corresponding Member of the Russian Academy of Sciences.
We started developing this technique in the mid-1990s. For over 30 years, we have been testing in various seismically active regions of the world. It outputs maps of the distribution of the conditional probability of a strong earthquake.
The technique uses a number of prognostic features and these features are mainly seismological, that is, based on studying the behavior of weak earthquakes in anticipation of a strong earthquake. The result is this: 60% to 80% of strong earthquakes occur in areas identified as abnormal using this technique.
— Does abnormal mean seismically active?
– Abnormal – means statistically different from the properties of other areas of the seismically active zone. Areas where earthquakes occur are known.
In Russia, this is Kamchatka and the Kuril Islands, then Sakhalin, Lake Baikal, Altai, Sayans, Southern Urals. However, weak earthquakes were recorded in the Southern Urals, but they still occur. also North Caucasus, Crimea. Meanwhile, earthquakes occur in the Kaliningrad region.
– Is there any periodicity in the activity of certain parts of the seismically active zones?
— Earthquakes are usually cyclical. There are also studies on this. For example, in the mid-60s of the last century for Kamchatka, Academician Fedotov introduced the concept of the seismic cycle.
He studied how earthquakes were distributed along Kamchatka’s east coast, collected data over several hundred years and proposed the concept of the seismic cycle. This concept, especially for Kamchatka, sounds like this: Earthquakes of 7¾ and above occur with a frequency of every 140 +/- 60 years in Kamchatka.
– Can such a model be derived for other abnormal regions?
– If you work, you can view for each region. But to study you need people and money, you need equipment.
– What are you currently working on?
– The latest discovery made by our group concerns the impact of a worldwide seismic echo. There was no such term before, we discovered this effect.
Imagine that there is a powerful earthquake somewhere deep in the earth, with elastic seismic waves emanating from its source in all directions. They then come to the Earth’s surface and generate surface seismic waves. They disperse in different directions from the epicenter of the earthquake and return to the same point after about three hours. At the same time, their amplitude increases. This creates a cumulative effect.
– And what does that mean?
– Increased amplitude of surface seismic waves returning to the epicenter can cause a second shock (aftershock). The main may not be more powerful than the initial shock, but it can destroy so much that the initial shock did not have time to destroy, and most importantly, damage the rescue services that have already begun to unravel the wreckage. save people. So rescuers can fill it too.
How often does this echo occur?
“Not every earthquake. With a strong earthquake, it can be fixed only in 40% of cases. Why we only know about 40% of it yet. We tried to examine in which regions this effect occurred mostly. However, we did not find such regions. So many questions remain unanswered for now.