Fig. 1From: Probabilistic Volcanic Ash Hazard Analysis (PVAHA) I: development of the VAPAH tool for emulating multi-scale volcanic ash fall analysisSchematic representation of the four stage procedure for PSHA: 1. Source; 2. Recurrence; 3. Ground Motion and; 4. Probability of exceedance (modified after TERA (1980) and Musson (2000))Back to article page