Seismic Deformations in Kyrkhudzhra ancient settlement on the Silk Road in Pap Region of Uzbekistan

Results obtained during archeological and paleogeographic studies testify a fact that delta part of the Gavasay river (tributary of the Syrdariya river) was cultivated in X century BC. Irrigation agriculture was flourishing during 500 years here. Pap (Bap) city with its square 10 ha was built in V century BC in territory of Kyrkhudzhra ancient settlement. The city consists of three parts: citadel, shahristan, and suburb (rabat). After 4 centuries Kyrkhudzhra, as well as all other cities of the northern Fergana, suffered from a strong earthquake in 90s BC. New fort walls of 8 m width were built in Kyrkhudzhra after this, with old walls used as a basement. In IV–V century AD because of strong destructions during next strong earthquake the population left Kyrkhudzhra settlement. Severe destructions and damages of specific structure revealed during the study point undoubtedly on seismic genesis of deformations in Kyrkhudzhra settlement. Judging by a fact of impossibility to determine a systematics in Kyrkhudzhra ruins, the source of ancient earthquake was near the settlement. The settlement itself is on rewashed adyrs – growing intradepression anticlinal uplifts. Seismically active faults located under adyrs are responsible for uplifts’ formation, growth, and seismic activity. Rupture planes formed during ancient and recent strong earthquakes are also under the adyrs. Analysis of existing geological and tectonic materials on study region has allowed revealing geological reasons of seismic processes. These processes are predetermined by neotectonic history of tectonic development and by the position of the North Fergana seismic zone in general structure of the Western Tien Shan. It is necessary to consider an important factor of increasing of the seismic risk because Namangan Oblast’ is in foothill territory – directly in the North Fergana fault zone and concurrently in flexure-rupture zone of the same name. Thus, Namangan Oblast’ is in the sphere of their active influence. Summarizing, let’s note that from one hand, geodynamic processes tied with tectonic regime of the North Fergana fault and flexurerupture zone with the same name are continue to develop. On the other hand, taking into account strong earthquake reoccurrence interval, an absence of strong earthquake with magnitude of М ≥ 5.0 in Namangan seismic zone during more than 36 years is a significant reason for declaration of alarm of expectation of the strong earthquake with М ≥ 5.0 in Namangan Oblast’, including Pap Region where Kyrkhudzhra archeological monument is located.

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