(OUI Me Or GEOLOGY 
MAY—FUNE, 1900 
METHODS OF STUDYING EARTHQUAKES 
I PROPOSE in this paper to consider the methods of studying 
earthquakes of a moderate degree of intensity, z. ¢., those which 
disturb areas of not more than a few thousands of square miles, 
and which as a rule are too weak to cause any very serious 
damage to property. Of such earthquakes, about ten or twelve 
are felt every year in Great Britian; the majority are slight, but 
once in four or five years a shock will occur that is noticed over 
a district containing more than 50,000 square miles. The 
methods of investigation do not, however, vary much in these 
cases; but, as they can only be applied with success in rather 
populous countries, it seems possible that they may be as useful 
in certain parts of the United States as they have already proved 
to be in the British Isles. 
~The whole aim of an earthquake inquiry has been widened 
during the last ten years. It is no longer merely a question of 
determining the position of the epicenter, though this is still one 
of the first problems to be solved. We have to ascertain not 
only the place where a fault-slip occurred, but the direction of 
the originating fault, its hade, and the nature of the movement 
which gave rise to the shock; for the earthquake is but a pass- 
ing incident in the growth of a fault. It is the transitory effect 
on the surface.of a displacement, within the earth’s crust; and 
Vol. VIII, No. 4. 301 
