Vol. 58.] INVERNESS EARTHQUAKE OF SEPTEMBER 1901. 393 
Earthquakes of 1890.—The last strong earthquake in the 
Inverness district occurred on November 15th, 1890.' It seems to 
have heen preceded by several slight earth-sounds, and was 
followed by not less than ten after-shocks, the series ending on 
December 14th. The epicentre of the principal earthquake was 
situated in lat. 57° 25:0’ N., long. 4° 10°8’ W., or 44 miles 
S. 21° HE. of Inverness, and 43 miles from the fault-line. As 
the longer axes of the isoseismal lines ran from N. 48° E. to ~ 
S. 48° W., it seemed to me probable that this shock was caused 
by a slip along a fault passing through a point about 1 mile 
south-east of Daviot, inclined at an angle of 13° to the boundary- 
fault, and hading to the north-west. JI have re-examined the 
evidence on which this conclusion was founded; and, though I 
am unable to interpret it otherwise, I think it possible that a larger 
series of records might have led to a different result. 
The epicentre of this earthquake lies outside the area represented 
in the map on p. 392; but a line drawn through it at right angles 
to the fault-line would pass very nearly through the centre of the 
principal earthquake of 1901. The small crosses( x ) mark the epi- 
centres of two of the after-shocks in 1890, those of November 15th, 
6.15 p.m., and December 14th, 3.30 a.m.: the latter being quite close 
to the epicentres of two after-shocks (m and q) of the recent series.” 
If the principal earthquake were due to a slip along the boundary- 
fault, there is thus an evident displacement of the focus in 
subsequent shocks towards the south-west. 
Fore-shocks of 1901.—Between December 14th, 1890, and 
the summer of 1901, no earthquakes, so far as I am aware, were felt 
in the Inverness district. The stresses tending to produce slipping: 
were clearly increasing along the whole portion of the fault between 
Loch Ness and the sea. Here .and there, however, were certain 
small areas of the fault-surface in which the resistance to slipping 
was greater than elsewhere ; and this resistance had to be overcome 
before any general movement could take place. One of these areas 
was situated about half a mile north-east of the end of Loch Ness, 
and the slip here gave rise to the first shock which attracted 
general observation. Two others, if we may rely on solitary 
records, existed farther to the north-east, where the resistance 
gave way within three hours of the occurrence of the principal 
shock. 
Principal earthquake of 1901.—The removal of these 
small obstructions helped to equalize the effective stress along 
several miles of the fault; so that the next displacement, which 
resulted in the principal shock, took place over a region extending. 
* Quart. Journ. Geol. Soe. vol. xlvii (1891) pp. 618-32. 
* The epicentre of another shock of the 1890 series (November 16th, 
8.30 p.m.) lies about half a mile west of Dochgarroch. ‘This point is on. 
the north-west side of the fault, and may be incorrectly determined owing to 
the scantiness of the evidence. 
