Flash floods are one of the most dangerous hydrometeorological events in the world. The current study investigates flash floods on the northern Black Sea Coast. The data about stochastic and relatively stable factors of flash flood formation (such as hydrological, meteorological, lithological, geomorphological, and anthropogenic parameters) were collected for 22 events. The main trigger of flash floods is heavy rainfall of high intensity in the region but in some cases flash flood occurrence is connected with combinations of several non-critical factors. The small watershed area (<351 km(2)) of river basins experiencing flash floods promotes very rapid flow concentration. Analysis of extreme precipitation demonstrates significant increasing trends in river basins on the Crimean Peninsula and decreasing a maximum precipitation amount in 5 days (r5d) and 1 day (r1d) in river basins in the Caucasus Black Sea Coast in the 21st century as determined by processing of Integrated Multi-satellite Retrievals for Global precipitation measurement (IMEGR) satellite data. At the same time land network data indicates increasing r5d at the Anapa and r1d at the Tuapse meteorological stations in 1961-2020. More frequent occurrence of flash floods has been suggested in the area due to statistical analysis of the longest precipitation ranges. The main reason for significant social and economic damage is uncontrolled human activity in flooded areas on the northern Black Sea Coast. (c) 2024 International Research and Training Centre on Erosion and Sedimentation. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY- NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

The deformations revealed by us in the ancient buildings of the village of Tsymyti indicate very strong seismic oscillations. The displacement of a block weighing 25 t against the slope of the relief indicates very strong accelerations of the soil-more than 1 g. Thus, the local intensity of seismic oscillations is at least Il = IX-X. In the walls of ancestral towers and burial crypts, it is possible to identify a significant number of extended interblock cracks, tilts, and collapses of walls and their parts. Rotations of building elements and deformations of window openings are also revealed. The distribution of the tilts of the walls shows their general declination to the west. According to the same azimuth, the abovementioned multiton block was ejected. The deformation of the window openings also took place in the walls of the sublatitudinal orientation, i.e., possibly from the western direction. The age of the towers in Tsymyti has two periods: 15th-16th centuries (use in the construction of dry masonry without cement) and 16th-17th centuries (use of masonry with cement mortar). It is possible that the change in the type of construction was caused by a seismic event. The same earthquake, apparently, damaged the Dzivgis fortress, located lower down the valley of the Fiagdon River. The trend of the outer wall of the fortress coincided with the direction of seismic oscillations (along the east-northeast-west-southwest axis), which approximately coincides with the sublatitudinal direction of seismic oscillation in Tsymyti. The first earthquake probably also damaged the Gutnov family tower in Dzivgis, built in the 15th-16th centuries. The tower was mostly repaired, and the cracks visible in the walls of the tower to this day appeared in it during the second earthquake, which apparently caused the destruction of buildings in the village of Dzivgis. The age of these buildings dates back to the 18th-19th centuries. The age of the necropolis in Tsymyti was determined by archaeologists as the 17th-18th centuries. Heavily destroyed crypts are apparently a consequence of the second earthquake in the region. The crypts that received minor damage are probably the result of the third earthquake. In Dzivgis, in the 19th century, the third earthquake led to a rockfall that deformed the metal cemetery fences; this seismic event occurred after 1878. Additional field and desk studies are necessary for a more complete parameterization of ancient seismic events, as well as the localization of ancient epicentral zones in certain structures of the crust of the region.