The walkway at Waimangu
Valley has been constructed
around a series of craters which
were formed by the 1886
Tarawera eruption. Currently no
track exists giving access to three
of the craters, namely those on
top of Mt Haszard, the prominent
knoll to be seen behind Inferno
Crater as viewed from near the
tearooms. This small eminence
is itself a rhyolite dome formed
during an eruption more than
60,000 years ago, and possibly at
much the same time as its larger
neighbour Te Hape o Toroa which
forms the sky-line to the left of
the line of craters. Mt Haszard
was given its name by the
geologist Dr James Hector
shortly after the Tarawera eruption to honour the memory of
school teacher Charles Haszard and members of his family
who were killed at Te Wairoa during that upheaval.
The three craters on top of Mt Haszard in order of decreasing
size are Black Crater, Fairy Crater, and Raupo Pond Crater.
Since 1886 it seems that activity in Fairy Crater has been
confined to steaming ground.
In Black Crater as well as steaming ground there has been
minor mud-pool formation and an intermittent fumarole
(steam vent) has sometimes been active high on its southwestern wall. But shallow Raupo Pond Crater has from time
to time been much more vigorous.
An examination of Raupo Pond Crater has revealed that it is
crossed by an approximately east-west
fracture that extends well beyond
the crater itself in both directions.
11.3
This fracture appears to have
formed at the time of the 1886
eruption but it was covered by
ejecta at the time and not
recognised.
20.9
13.4
15
(Figures are
depths in metres)
Southern
Crater
On 21 February 1906 a hydrothermal explosion opened a vent
on a short length of the fracture in
Raupo Pond Crater. At first it was
hoped that the eruptions of the
by-then extinct Waimangu Geyser
might be duplicated in this new
locality but vigorous activity in
Raupo Pond Crater declined
rapidly and the new vent subsided
in quiescence.
Further short-lived eruptions
occurred from this vent and a new
neighbouring one in 1914 and 1915
and by the mid nineteen-twenties
the main vent was partly filled to
become an active mud pool. It’s
long axis coincided with the rift
whose exact line was marked by
the places where bubbles broke the mud
surface. During the late 1970’s the
mud pool activity became more
vigorous and the sound of its
thumping and splashing would
reverberate over the hill.
Rainbow
Crater
Raupo Pond
Crater
.
Black
Crater
Fairy
Crater
N
The feature by this time had been informally given the name
“Mud Rift".
Vigorous eruptions on 22-23 February 1978 took place in both
Mud Rift and Inferno Crater. The water of the lakelet in
Inferno Crater was discoloured to a uniform pale grey and it
was found that a new vent had been formed in the lakebed.
Mud Rift threw out some of its contents which lay plastered
on its upper walls and over the surrounding vegetation.
In May 1981 an even more vigorous eruption created two
new craterlets on the rift in Raupo Pond Crater and completely
emptied Mud Rift of its contents.
This event coincided with a period of high stands in Inferno
Crater lakelet, where water levels remained high for several
cycles. Since then the Mud Rift has become completely
inactive.
NOTE: It is strongly advised against exploring off the
tracks on Mt Haszard because the craters formed are
now largely overgrown and their ges invisible. Some have
places where the sides are vertical and even overhanging
and an accidental fall into any of them could cause serious
injury or death.
Information compiled by Professor RF Keam Physics Department University of Auckland
Waimangu Volcanic Valley, P O Box 6141, Rotorua, New Zealand
Phone 64 7 3666 137, Fax 64 7 3666 607, Email: [email protected]
www.waimangu.com