North-Central Section - 39th Annual Meeting (May 19–20, 2005)

Paper No. 16
Presentation Time: 8:00 AM-12:00 PM


MISCHLER, John A., Geology/Physics, Augustana College, 639 38th Street, Rock Island, IL 61201, WALKER, Richard T., Department of Earth Sciences, Oxford Univ, Parks Road, Oxford, OX1 3PR, United Kingdom and GONCHIG, Tsolmon, Department of Geology, Mongolian University of Sciense and Technology, P.O. Box 46/520, Ulaanbaatar, P.O. Box 46/, Mongolia,

The Jid Fault is a 60-km long right-lateral strike-slip fault. A 15-km long section of the fault between N49º27'32.6” and E91º43'25.1” appears to be almost pure right-lateral strike-slip to the north with a thrust component introduced further south as the fault changes orientation from trending north-south to northwest-southeast. At this change in orientation, the fault splits into three north-south splays. The westernmost segment appears to be mostly right-lateral strike-slip while the middle segment has a normal component of motion. The eastern segment follows an anticlinal ridge and has a thrust component. The three parallel fault strands probably form a flower structure of numerous fault strands narrowing into a single oblique strike-slip fault at depth. Well-preserved earthquake ruptures take the form of alternating tension cracks and pressure ridges which represent failure of the top few meters of soil cover in response to strike-slip motion at depth. Extension fractures in areas where the fault has a substantial thrust component are caused by collapse of the scarp.