Vol. 58.] INVERNESS EARTHQUAKE OF SEPTEMBER 1901. 381 
~Belsyde (near Linlithgow), Gullane (near North Berwick), and 
Dunbar. So far as I know, the earthquake was not felt in either 
Edinburgh or Glasgow, but the isoseismal 4 clearly passes to the 
south of the line joining these cities. The distance between the 
isoseismals 5 and 4 is 20 miles on the north-west, and 35 miles on 
the south-east side. 
Isoseismal 4 may be regarded as the boundary of the disturbed 
area, for no observations seem to have been made outside it. The 
disturbed area is thus 215 miles long from north-east to south-west, 
198 miles wide, and includes about 33,000 square miles. 
Position of the originating fault.—Despite the some- 
what doubtful character of the three outer isoseismals, the other 
two furnish abundant evidence for determining the position of the 
originating fault. The direction of their longer axes shows that 
the average direction of the fault must be N. 33° E., and 8. 33° W. 
As the distance between the isoseismals is greater on the south- 
east than on the north-west side, we may infer that the hade of 
the fault is to the south-east. Again, the intensity of the shock 
being greater on the side towards which the fault hades, it follows 
that the fault-line must lie a short distance (about a mile or so) on 
the north-west side of the centre of the isoseismal 8. 
The correspondence between the positions of the great boundary- - 
fault and of the fault inferred from the seismic evidence, is so close 
that there can be little, if any, doubt that the earthquake was due 
to a slip along this fault. It will be seen that the evidence of the 
after-shocks offers additional support to this conclusion. 
Nature of the shock.—Contrary to the general rule, there 
was little variation in the nature of the shock throughout the dis- 
turbed area. This will be seen from the following accounts, which 
are selected as typical from among those written by observers who 
were awake when the shock began :— 
Inverness.—A gentle movement, followed by an extraordinary 
ulvering, which increased in force for 2 or 3 seconds, and then 
ecreased for 2 or 3 seconds; just as the quivering was about to 
cease, there was a distinct lurch or heave, after which the vibration 
was much more severe than before, and lasted several seconds longer 
than the first part of the shock. 
Dalarossie.—The first indication was a loud sound, as of an 
express train coming from the east, rushing along close to, and then 
under, the northern wall of the house; this lasted for a few seconds, 
and towards the end of it the house vibrated. Then succeeded an 
interval of quietness for about one second, followed by a terrific 
burst or crash, not unlike the crash of a loud thunder-peal of about 
2 seconds’ duration, during which the house distinctly heaved up 
once and then sank back. After another brief interval of quietness, 
there was a low rumble, somewhat like the sound of a dying peal 
of thunder, 
Aberlour.—A noise, like that of a traction-engine, was first 
heard, and at the same time a vibration was felt, such as is generally 
