Pseudotachylyte was found along the Nojima fault at Nojima-Hirabayashi, Awaji Island (Figure 1, Otsuki, 2000) where the largest displacement of surface rupture was observed in 1995 Hyogo-ken Nanbu earthquake (Awata et al., 1996). On August 2000, a fault outcrop was excavated at this location and 20 m long and 3 m wide fault zone was exposed (This survey was held by Prof. Otsuki (Tohoku University) supported by Fault Anatomy project). Pseudotachylyte is formed by melting of rocks associated with co-seismic slip. We introduce the detailed photographs of pseudotachylyte, which suggest physical properties and dynamic features of fault zones. We are analyzing microscopic and mesoscopic properties of the pseudotachylyte and find some interesting flow textures developed between the pseudotachylyte and surrounding fault gouge layers. These microtextures will be valuable sources for considering the mechanical/chemical conditions of fault rocks during frictional shearing.
The Geological Society of Japan