The subsurface markers for identifying wrench structure could be concluded as follows:(1)echelon structure 3(2) flower-form structure;(3)braid structure;(4).narrow deformationzone;(5) deep narrow half-graben;(6) narrow thick coarse deposit zone;(7) unmatchablestrata across a fault;(8)swaying and variable fault dip;(9)clutter seismic reflection.However

the trend of overstating the effect ofwrenching may occur due to inaccurate identification in actual application

especially in identifying echelon structure and flower-formstructure.The key problems are(1) tenso-echelon does not always indicate wrench fracture;(2) as for the shallow-rooted structures in a basin

"basement-involving"could not be theessential identificative criterion of wrench fault I(3)the back--thrust blocks that widely developed in oil provinces in West China are mostly not flower-form structures.