Relationship between ground and crustal deformations in the western part of the Oginojo Anticline, synchronous with the 2007 Niigataken Chuetsu-oki Earthquake

Abstract

We investigated ruptures in the asphalt and concrete pavement of roads in the uplifted belt of the western wing of the Oginojo Anticline, where crustal deformation associated with the 2007 Niigataken Chuetsu-oki Earthquake (Mj 6.8) has been detected using synthetic aperture radar (SAR) interferometry. In the region of uplift (displacement >8 cm) on the western limb, the pavement was ruptured at many places, but not by faults. Open cracks are dominant in the uplifted belt, whereas cracks generated by gravity sliding or sagging of roads were observed over large parts of the study area. Striations on the bedding planes on the western limb indicated flexural slip folding mechanism; however, we observed no bedding plane slips. These observations suggest that open cracks of the uplift region were generated in response to local coseismic uplift.