Haast.—Recent Earthquakes on Land and Sea. 147 
Ant. XXIL—On the recent Earthquakes on Land and Sea. 
By Juxrus Haast, Ph.D., F.R.S. 
[Read before the Philosophical Institute of Canterbury, 9th September, 1868. ] 
[ABRIDGED.] 5 
BEFORE proceeding to make a few remarks upon the contents of the valuable 
paper of Captain Gibson, to the reading of which we have just listened, 
I think that some general observations on earthquakes, as experienced on 
land and sea, their causes and effects, would not be here out of place. 
I should also like, with your consent, to test, by the observations which 
we were able to make in New Zealand, some of the theories by which the 
origin and propagation of these most formidable and greatest phenomena of 
nature have been explained. 
* * * * a oo * * * 
The first sign of disturbance experienced in Christchurch was a slight 
shock of an earthquake felt by several of our fellow-citizens in the early 
morning of Saturday, the 15th of August, amongst whom, Mr. A. T. W. 
Bradwell gave me, the same day, the best account. It was about 3 o’clock 
in the morning that he felt a slight shock of an earthquake, travelling 
apparently from S.W. to N.E., accompanied by a slight subterranean 
rumbling sound. As buildings move generally in the direction from which 
the vibratory movement reaches them, it is highly probable that this earth- 
quake came from the N.E., from which direction the earthquake waves in 
the sea appeared also afterwards on our coasts. 
There is no doubt in my mind that we can associate the earthquake 
waves, in the sea at least, with the minor shocks experienced on the land. 
Unfortunately, we do not yet possess the necessary data to calculate the 
velocity of these minor shocks, which are without doubt the last pulsations 
of a very severe volcanic earthquake, the focus of which is situated in a 
N.N.E. or N.E. direction from New Zealand. 
And I may observe here, that a voleanie central or linear earthquake 
may be very severe at or near its focus, although its effects are confined to 
a comparatively limited area round about it. Thus the slight earthquake 
shock experienced in the early morning of the 15th of August, might have 
been of a very local character only, although the disturbance on the sea 
bottom, near its focus, was so enormous that the effects were felt, as far as 
we know already, on the coasts of New Zealand, Australia, and the Chatham 
Islands. And whilst the disturbance in the level of the sea, from the 
impetus given, was such that it was felt over a tract of country several 
thousand miles in diameter, the oscillations of the earth's crust may have 
been confined to as many hundred miles only. Supposing that the Chatham 
