Quantitative determination of the lowest density domain in major fault zones via medical X-ray computed tomography

Abstract Determination of the youngest active domains in fault zones that are not overlain by Quaternary sedimentary cover is critical for evaluating recent activity, determining current local stress field, and mitigating impacts future earthquakes. Considering exhumation a zone, domain zone supposed to correspond activity at minimum depth buried fault, such most vulnerable area, which possesses lowest rock/protolith density ratio, assumed be indicative this activity. However, it difficult measure rocks map ratio across given zone. Here, we utilize medical X-ray computed tomography (CT), non-destructive technique observing analyzing materials, investigate characteristics several their surrounding regions Japan, attempt determine based on its CT numbers, function effective atomic number rock protolith. We first density, void inactive rocks, respective protoliths. then calculate numbers after reducing beam-hardening effects samples study relationships among number, number. demonstrate decrease as identified outcrop observation, approached, region with defines z one. also discuss relationship between major points considered when from determined