Spatio-temporal hazard estimation in the central silicic part of Taupo Volcanic Zone, New Zealand, based on small to medium volume eruptions

We explore how volcanic hazards in a silicic volcanism-dominated caldera systems can be assessed by spatial and spatio-temporal statistical models using similar treatment to that applied to dispersed mafic monogenetic volcanic fields. The central part of the Taupo Volcanic Zone is an ideal location for such study, containing more than 300 small to medium volume eruptions identified as having occurred in the past 350 kyr. The spatial distribution of vents with respect to the location of faults indicates a very strong local tectonic control on new vent openings, which commonly manifests in eruptions characterized by fissure vents. Kernel density estimates, along with the migration of volcanic foci in the last 100 kyr, suggest the bipartition of the caldera system activity, separated by an approximately 20 km wide vent-free section of the Taupo rift between the Waikato River and the southern extent of the Kapenga caldera. The heterogeneity in the spatial pattern of vents in the vicinity of different calderas suggests that the caldera structures themselves exert considerable infuence on the location of post-caldera volcanism. The spatio-temporal analysis fails to identify a local maxima of spatio-temporal intensity corresponding to post-Oruanui volcanism of Taupo volcano, in contrast to that observed at Maroa and Okataina Volcanic Centres. This deficit of events indicates that the Taupo caldera system is behaving atypically, relative to the post-caldera stage of other calderas of the Taupo Volcanic Zone.