Fault “Corrosion” by Fluid Injection: A Potential Cause of the November 2017 5.5 Korean Earthquake

Figure 3

Enlargement of the intersection in Figure 2(b) between well PX-2 and the Namsong Fault, showing (a) reports of fault gouge, cataclasite, and loss of drilling mud, from drilling logs, and (b) proportions of fault gouge from subsequent laboratory analysis of cuttings. Modified from Figure O-3(e) of [5]. Many of the larger (centimetre-sized) cuttings from this depth range were “mud balls” containing large proportions of fault gouge and cataclasite; [5] provides further details. Interpretation of impermeable fault core and permeable fault damage zone, after [86, 87].