Potential physical effects of any future 1886 type eruption from Tarawera Volcano on the Bay of Plenty Region. (2003)
AuthorsBarnard, Scott Trevorshow all
Tarawera Volcano is cl8 ka, and has experienced 5 eruptive episodes in that time. The last eruption occurred in 1886, dispersing more than 1.3km3 of ejecta over the Bay of Plenty region, in what was the largest basaltic eruption recognized in the 1.6 Ma history of Taupo Volcanic Zone. Despite Tarawera's violent history, several urban centres are located within a 25km radius of the volcano. These centres, along with more distal towns such as Whakatane and Tauranga will be vulnerable to future basaltic activity at Tarawera.
The 1886 eruption killed over 120 people, and devastated large areas that are now inhabited. Using that eruption as a model of a probable worst-case scenario, potential hazards can be identified that may affect contemporary communities; The vulnerability of the region to these hazards is assessed on both effects of the 1886 eruption and the effects of recent eruptions from other volcanoes on lifelines, infrastructure and agriculture. The 2002 eruption of Mount Etna has also provided an opportunity to closely examine the effects of basaltic volcanism on a modem community.
Several types of infrastructure have been identified as being particularly vulnerable to an 1886 type eruption. These include buildings near the volcano, roads, and electrical distribution networks. Rotorua would be extremely vulnerable during a worst-case scenario, as up to 300mm of tephra could fall on the city. Whakatane's water supply will be likely to fail during an eruption, but more distal areas such as Tauranga will survive without sustai~g much damage. Base surges from likely phreatomagmatic activity in the Rotomahana-Waimangu geothermal field may destroy houses, a large section of State Highway 2 and several kilometers of220kV transmission lines.
Recommendations are presented of measures that will decrease the vulnerability of the region to an 1886 type eruption.