Published on 12 January 2018
The Sardarapat structure represents a swell-like uplift 40-70 m high above the Ararat Depression surface, consisting of a system of swells and hills. Identifying if the Sardarapat structure is an active fault and a linear seismogenic zone is a sensitive issue both for understanding the recent geodynamics of the Ararat Valley, and for the seismic hazard assessment. The studies were aimed at applying complex surveys to answer this question and to improve the current estimate of potential maximum magnitude of the seismogenic zone. The tasks included revealing any surface ruptures or soil liquefaction effects by the techniques of geological-geophysical field studies. In terms of kinematics, the identified ruptures are reverse faults with vertical dipping plane. Apparently, the surface ruptures are associated with a young active fault, related to some older fault represented by the Sardarapat structure. The geo-radar technique was applied to identify anomalies in the supposed concealed fault trace areas. The granulometric analysis helped to determine if the sand dikes could
have been generated by soil liquefaction. The granulometric test values suggest clearly that signs of soil liquefaction caused by a strong earthquake are common within the Sardarapat structure zone. The geo-radar survey identified anomalies of a certain type interpreted as shallow concealed faults. The archeoseismological studies confirmed that a strong earthquake occurred in the period of the 8th-2nd century BC. The data produced by the studies were all introduced into the GIS database further used with ArcGlobe and ArcScene software to compile a 3D GIS model of the Ararat Depression. The new data bear clear evidence that the Sardarapat structure is an active fault with reverse-fault mechanism and a seismogenic zone with the potential of M=6.6-7.0. The latest strong earthquake between the 8th and the 2nd century BC left signs of surface break and soil liquefaction.
Tags: активный разлом, разжижение грунта, сильное землетрясение, георадар, магнитометрия, GPS
ISSN 1998-4502 (Print) ISSN 2499-975Х (Online)