Geophysical processes and biosphere: article

Аnnotation: In result of conducted study in Derbent it was established that its monumental fortification constrictions erected in the end of 560th AD were undergone by numerous strong seismic shocks during whole period of their existence. By age of the deformed masonry we can determine approximate ages of the strong seismic events, shocked Derbent during whole its history. 1) Late Sassanid and Late Arab time (VI - beginning of VIII century AD) - significant clockwise rotations around vertical axis along the interblock seams in part of the Sassanid masonry of a curtain and a tower of the southern citadel wall in result of the seismic shocks. Numerous rebuilding and restatements observed in defensive city walls. The Sassanid masonry before and after repair/rebuilding. Building works during the Arab period, especially in VIII century, described in written sources, were caused probably not only by military confrontation of the Arab Caliphate and Khazar Khanat (Arab-Khazar wars) which led to damage of some parts of the defensive walls, but also by the seismic activity. 2) A border of the Arab period and the time of Derbent Emirate (VIII-XI centuries) - significant brake in upper part of the northern city wall between the citadel and Dzharchi-Kapy Gate. Arrival of the seismic shock from North-West. 3) Repair-building works on reinforcement of the defensive walls of the citadel of the Sassanid time during the existence of the Derbent Emirate and Seljuk period by later masonry (including rusticated one). These works could be not only a consequence of destruction of fortifications during a period of confrontation of Derbent emirs with the city nobility and with the Shirvan shahs state, that is described in «Tarikh al-Bab» chronicle («History of Shirvan and Derbent»), but also by the seismic destruction of the fortifications. 4) Mid XIV century (1360th) - time of destruction and repair of Dzhuma-mosque. Arrival of the shocks from the North. These destructions apparently caused the following building activity in Derbendi Shirvan shahs period in XV century, especially during the reign of Khalilulakh the Ist (1417-1462) which was described in the building incriptions and the characteristic features of the «Shirvan» architecture (Orta-Kapy Gate, Minaret-Mosque). 5) End of XVIII century - time of repair of Women Bath-House. Propagation of maximal seimic oscillations along the sublongitudinal axis. Tectonic displacement of basement blocks and destruction of Peter the Ist hut.