Comprehensive Fault Slip Variation Effects on Deformation Partitioning in the Eastern Turkish Plateau

Abstract:

Slip vectors’ spatial differentiation is generally interpreted to link with changes in slip rate along faults. Here, we present some new evidence to challenge this viewpoint. A broad span of observations including fault-strike orientations, maximum shear strain axes and decomposed slip vectors from geodetic measurements are considered over a wide region extending from eastern Turkey to northwestern Iran. Our results indicate that the inconsistency between the fault-strike directions and the maximum shear strain orientations largely reflect local strain accumulation gradients at their traces. Oblique shear is partitioned into strike-slip along the shear zone and thin-skinned shortening or pull-apart extension at the faults' termini and overlaps. Extrusion of crustal fragments to the northwest is partly absorbed by differences of intracontinental deformation. Therefore, we suggest that the fault-strike orientations’ change from the NW- to WNW-trending and the associated shear-strain difference produce the localization of strain accumulation gradients near the breaks of the 2020 Qotour earthquake doublet (Mw 5.8, 6.0), NW Iran. There is no simple and direct relation between slip rate changes and strain localization, but a more comprehensive variation mechanism dominates the differentiation of partitioning in the eastern Turkish Plateau.