Volcanoes - Ministry of Civil Defence and Emergency Management

The Okataina Threat
for the Bay of Plenty
John Thurston, Project Manager, CDEM
Group Plan, Bay of Plenty
It is all relative I suppose. Living with the threat of a
volcanic eruption. A number of years ago I lived at Scott
Base, Antarctica for five months during a Polar Summer
with the active Mt.Erebus dominant in the background.
Did I really care or did it worry me that it may erupt during
my stay on the ice? It becomes hard to rationalise the
acceptance of something on your doorstep that could
deliver you into all eternity yet not be overly concerned
Taupo Volcanic Zone. The Okataina Volcanic Centre is
recognised as having the most potential volcanic activity
in New Zealand.
Would we cope with another Kaharoa eruption
and ash layering of our region? Simply we would not if
we have not done the planning groundwork.
GROUNDS FOR CONCERN
Does anyone care? Should they be worried? Are
we saying to ourselves it won’t happen in my lifetime,
rather than it won’t happen at all. It will happen, but the
big question is when? While this is going on someone
has to take charge and implement the 4 Rs (Reduction,
Readiness, Response and Recovery) should an eruption
about it. Is this the process going on with those living in
the Bay of Plenty? I wish I knew. Does the uncertainty
work in favour of blocking out the likelihood of being dealt
the “losing marble’ of a volcanic eruption. Perhaps we
will never know, but we cannot leave it there. We must
recognise and be prepared for major problems centred
on a volcanic eruption in the Bay of Plenty or the ashfall
effects of a distal eruption in far away Taranaki, Auckland
or neighbouring Taupo.
There is plenty of evidence around us of past
volcanic eruptions here in the Bay of Plenty. You can
see the layers of pumice in road cuttings from the 1315
AD Kaharoa Rhyolite Eruption from Mt Tarawera as you
drive to Whakatane. Horticulturists use the pumice from
Otamarakau in hydroponics growing. We even export
it. The enormous reserves of pumice certainly indicate
the occurrence of an event of gigantic proportions
beyond our wildest comprehension.
The presence of pending and past volcanic
activity further dots our landscape. White Island
occasionally plumes away offshore to the northeast.
Mayor Island, dormant for many thousands of years,
is nearby for those living in the Western Bay. The
Okataina Volcanic Centre, with the obvious evidence
of the 1886 eruption and the Mt Tarawera fissure
or 'rift', overshadows Rotorua and forms part of the
Civil defence boundaries of the Bay of Plenty region.
53
TEPHRA
June 2004