A probabilistic assessment of eruption recurrence on Taveuni volcano, Fiji

Taveuni, a 437-km(2) oceanic intraplate volcano in the northeastern Fiji Gr oup, has been active throughout the Holocene and currently has a rapidly gr owing population. Alkali basalt magmas were erupted through monogenetic ven ts at constantly shifting locations along a SW-striking rift zone. Hence, q uantification of volcanic hazard, in both spatial and temporal terms, is of great importance for disaster management and development agencies. Unlike previous probabilistic assessments of hazards in volcanic fields, the activ ity on Taveuni is both more recent and on a lesser spatial scale. This enab les us to focus our attention on different aspects of the analysis. In part icular, we propose a first attempt at dealing with the imprecision and inac curacy inherent in volcanic eruption age data obtained via radiocarbon dati ng. Our results indicate that volcanic activity on Taveuni has a tendency t o occur in episodes. If this tendency is strong, the present hazard may be considerably greater than otherwise supposed. We also confirm an apparent t endency for the volcanic activity to migrate southwards along the Taveuni r ift axis towards the most densely settled area, and also the widest axial v ent zone. This indicates that the risk from volcanic activity is again high er than might otherwise be supposed. We estimate a Taveuni-wide probability of0.56 for renewed activity within the next 50 years. Such quantitative re sults can be utilised within loss estimations during the planning stages of new infrastructure and business developments at various locations on the i sland.