Dear colleagues! The further geophysicists delve into the study of natural phenomena, the more they feel an acute shortage of data for long periods of observation. This is especially true of the most extreme events in the life of the Earth. If, for example, within an active seismic zone in each individual point, a seven - point earthquake can repeat once every fifty to two hundred years, then the average repetition time of eight - point earthquakes is three times, and nine - point earthquakes are ten times longer. A unique event that occurs completely unexpectedly and lasts for a few seconds - this is how a strong earthquake appears before us. It is no coincidence that our success in predicting earthquakes has been so modest so far.

But, like any natural disaster, a strong earthquake is not just a natural phenomenon. When an underground shock strikes, the forces of the Earth meet not only with houses and dams: they also interact directly with human society. And this interaction is governed not only by the laws of geophysics, but also by the laws of psychology, sociology, history, and economics. There are cases when an earthquake undermined even the very foundations of local civilization. After the disaster, people left, leaving their homes and arable land. However, did this always happen after a major disaster? No, people's feelings are not so simple. It is possible to think that a person (and especially society) is relatively stable and quite easily tolerates a single impact of nature, no matter how severe it may be, but more often gives up before a series of repeated, even if not very serious events.

In the layman's view, there is a large, if not huge, difference in the response to the forces of nature in different civilizations. The high spiritual organization of the society of ancient Greece, its close attention to the forces of nature, the most detailed deification of the most subtle features of the surrounding world-all this is in striking contrast to the almost complete lack of data on earthquakes in ancient Greek sources, at least in sources accessible to the layman. On the contrary, the detailed chronicles of the Celestial Empire have preserved so much information about the earthquakes of the past two millennia that they served as almost the main source material for drawing up a map of the seismic zoning of China by Soviet scientists.

Should we assume that 2.5 thousand years ago the seismic activity of the Peloponnese, Thessaly and Lydia was much weaker than it is now? Can we hope that good evidence of earthquakes will be found in the Northern Black Sea region, Sogdiana, and many other territories of our country, whose study of the seismic past is very necessary for us now to assess such a danger in the future? Seismologists themselves cannot solve this problem without the help of historians. After all, information about earthquakes is scattered in numerous and diverse sources. Chronicles and chronicles, inscriptions on the walls of mosques and church books, tombstones and memoirs... Many historians, encountering an unexpected mention of a natural disaster in the sources, felt interest flare up for a moment, but then, preoccupied with the problems under study, they ignored the rarest find, and it again plunged into the ocean of historical information inaccessible to geophysicists.

Now seismologists are not driven by an idle interest in collecting facts. New technical methods make it possible, in cases where information about a single land plot is available, to-

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If the quakes are obtained from two, three or more points, we can estimate at least approximately such important parameters as the location and depth of the seismic source, and even its energy. Therefore, we decide to appeal to historians who have to deal with sources, with a request to collect or at least notice along the way with the main work any references to strong earthquakes on the territory of our country and on Earth in general. Of course, such research does not always give rise to the topic of historical research (although, apparently, it is possible to link periods of revival of seismic activity with the decline of the economy of certain regions in some era). But you can be quite sure that such information, combined with modern instrumental data, will allow you to more fully and reliably assess the seismic hazard, and therefore reduce the damage and grief that awaits people in the area of future strong earthquakes.

Geophysicists will be grateful for any evidence of past earthquakes discovered by historians and reported to the address: Moscow, D-242, Bolshaya Gruzinskaya, house N 10, Institute of Physics of the Earth of the USSR Academy of Sciences.

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