THE ACTIVE VOLCANOES OF NEW ZEALAND JO J 



the main eruption commenced and the great fissure began to open 

 in the mountain, commencing at the north end in the hump called 

 Wahanga. It passed through Ruawahia toward the basin now 

 occupied by Lake Rotomahana and formerly containing the small 

 lakes, Rotomahana and Rotomakariri. It opened under the lakes 

 about 2 : 30 a.m. with a terrific roar and a cloud of steam which rose 

 over 15,000 feet high. 1 This no doubt was due to the water rushing 

 into the heated zone and producing a great explosion of steam. 

 The result was the opening of a large pit, now occupied by Lake 

 Rotomahana, while the debris was scattered widely over the 

 country. The finer materials were carried out to sea over the Bay 

 of Plenty, as indicated on the accompanying map (Fig. 1). It 

 has been estimated that from the great fissure from 520,000,000 

 to 620,000,000 cubic yards of material was thrown out and this was 

 spread over an area of almost 6,000 square miles, of which 1,500 

 square miles were damaged more or less severely from the agri- 

 cultural standpoint. All habitations within four miles of the 

 mountain were destroyed and 116 people killed. Most of these 

 were natives, and while the majority of them were killed by the 

 falling materials burying them, some around Rotomahana, where 

 the natives often gathered, were literally carried away by the 

 explosion. At Te Wairoa the buildings were crushed in and all 

 vegetation destroyed or very severely damaged. There is still 

 very little vegetation near the mountain, but it is interesting to see 

 how quickly it has re-established itself at Te Wairoa, where the 

 eucalypti are already fourteen to fifteen inches in diameter and 

 other trees of less rapid growth are eight inches. The fern, like 

 the braken of this country, establishes itself very quickly and 

 flourishes on the acid soil. In many places the charred remains of 

 trees are found, not only in the ashes of this eruption, but also in 

 the ashes of earlier date. 



The main eruption lasted about five hours, although the more 

 violent part was probably over in less than an hour. Earthquakes 

 continued for many days and there seems to have been some unusual 

 activity in the hot springs around Rotorua. There have also 



1 According to S. P. Smith the measured height was 15,400 feet. "The Eruption 

 of Tarawera," A Report to the Surveyor-General, New Zealand, 1887. 



