508 Transactions. 



(c.) Many short and jerky, hut generally harmless, quakes felt in 

 Christchurch, Banks Peninsula, and mid Canterhury. Chief shocks : 

 31st August, 1870; 27th December, 1888 (VII, R.-F.); &c. Focus of 1888 

 shock, sixteen miles long, from west-south-west to east-north-east, twenty- 

 four to twenty-five miles below surface, being deepest ascertained origin 

 in New Zealand region. 



These origins form a line parallel to the general axis of the 

 land. It is quite possible that the loading of the sea-floor by 

 the detritus brought down by the rivers of Canterbury is a 

 contributing cause of the earthquakes of this group. 



Group III. — Wellington earthquakes of January, 1855, and Cheviot 

 earthquakes of November, 1901. 



Remark has already been made as to a possible relation 

 between these origins. The great earthquakes of October, 

 1848, probably came from the same region as those of January, 

 1855. The chief shocks of both series did extensive damage 

 to property, and caused the formation of large rifts in the 

 earth's surface ; they are the only seismic disturbances since 

 the settlement of the colony that can be assigned to degree X 

 on the Rossi-Forel scale. 



Group IV. — (a.) Region about twenty-five to thirty miles in length, 

 and, say, ten miles or less in width, running nearly north-north-east from 

 middle of Lake Sumner, about twenty miles below the surface, whence 

 proceed most of the severer shocks felt from Christchurch to the Amuri, 

 and a large number of minor shocks. Chief earthquakes : 1st February, 

 1868; 27th August to 1st September, 1871; 14th September and 21st 

 October, 1878; 11th April, 1884; 5th December, 1881 (VIII. R.-F.), when 

 Christchurch Cathedral spire was slightly injured; 1st September, 1888 

 (IX, R.-F.), when upper part of same spire fell, and still more severe damage 

 was done in the Amuri district. 



(b.) A small, shallow origin not more than five to ten miles below the 

 surface, a few miles south of Nelson. Earthquake: 12th February, 1893 

 (VIII to IX, R.-F.) ; chimneys thrown down and buildings injured. 



(c.) Origin in Cook Strait, north-north-east of Stephen Island, about 

 ten miles wide, and apparently traceable with few interruptions nearly 

 to mouth of Wanganui River ; depth, fifteen miles or more. More than 

 half the earthquakes recorded in New Zealand belong to this region ; 

 earthquake of 8th December, 1897 (VIII to IX, R.-F.), and other severer 

 ones come from south-south-west end. 



(d.) An origin near Mount Tarawera, with a large number of moderate 

 or slight shocks, most, but not all, volcanic and local in character — e.g., 

 those of September, 1866, and those of June, 1886, which accompanied 

 and followed the well-known eruption of Mount Tarawera. 



These origins of Group IV, (a), (6), (c), (d), are nearly in 

 a straight line on the map ; on or near the same line are the 

 origins of earthquakes felt in the Southern Lake district (15th 

 December, 1883, &c), the volcanoes Ruapehu, Ngauruhoe. 

 Tongariro, Tarawera, and White Island. It is evident that 

 this line, which, like the rest, is parallel or nearly so to the 

 general axis, is a line of weakness or of unstable equilibrium. 

 Hence the adjusting movements that have caused earthquakes 



