40 BEPOBT — 1891. 



Of the isolated earthquakes the WeUington records show by 

 far the most, the number being 121. Wanganui is second* (41) ; 

 and Eotorua (32) third. Next after Kotorua we have — from 

 1848 to 1890: Nelson, 24; Christchurch, 23; New Plymouth, 

 23 ; Napier, 21 ; Queenstown, 18. 



These apparently isolated or local earthquakes, or the re- 

 cords of them, are more uncertain than the 116 felt at three or 

 more places, upon which the general shading is founded. The 

 latter I think we are justified in taking as fairly accurate, 

 especially when the large number of shocks included is taken 

 into account. If we apply tests, such as using the earthquakes 

 of the last few years only, we find that the general shading 

 remains the same relatively, but the relative darkness of the 

 small circular areas varies considerably. 



The radius of the small circles (10 miles) is more or less 

 arbitrary. It was suggested by the fact that from private infor- 

 mation I was aware that some of these isolated shocks were 

 felt at that distaiice from the respective towns. 



It may be convenient to state here that the earthquakes im- 

 mediately connected with the eruption of Mount Tarawera in 

 1886 have not been included in the list of earthquakes, as I take 

 it that they should be considered as part of the phenomena of 

 the eruption : seventy-one shocks were felt at Opotiki at the time 

 of the great outburst and the few hours that succeeded. I 

 have not excluded the warning earthquakes that preceded the 

 eruption, or those that took place after activity had ceased, for 

 probably they belong to the same class as all the other earth- 

 quakes confined to that region. It is to such earthquakes, 

 notably perhaps to earthquakes like those of 1866, that 

 the term "volcanic earthquakes" may be applied, or the 

 expression be used that " the earthquake is an unsuccessful 

 attempt to form a volcano." That is to say, the cause is 

 possibly the presence of w^ater in a cavity or quasi-cavity at 

 high pressure and temperature. At Euapehu and Tongariro 

 we might expect similar shocks ; and I believe shocks of a 

 very slight nature are felt at Euapehu, but only, as a rule, 

 on the mountain itself. There is a general impression that 

 some of the shocks felt in the south-west portion of the North 

 Island have proceeded from the Euapehu-Tongariro district ; 

 I have searched right through the records for indications of this, 

 and have found not a single piece of evidence in favour of it : 

 on the contrary, the data of the earthquakes said to have come 

 from that supposed origin point to utterly different conclu- 



* It is possible that if as good records had been kept at Wanganui as at 

 Wellington tho numbers might have appeared more nearly equal. At all 

 events, the number of earthquakes felt at one or two places only during 

 1890 shows : Wellington, 3 ; Wanganui, 10 ; Kotorua, 8. 



