DISTKIBUTION IN SPACE AND TIME. 233 



Calabria are usually only felt on the western side of the 

 Apennines, but instances have occurred when they have 

 crossed this barrier. In 1801 the earthquake of Cumana 

 crossed a branch of the coast range. 



Sometimes earthquake boundaries give way, and 

 countries which they sheltered subsequently become ex- 

 posed to all disturbances. The true explanation of this 

 is probably in a shifting of the centre of seismic activity. 

 Thus up to December 14, 1797, although Cumana was 

 often devastated, the peninsula of Araya was not hurt. 

 On this date Araya commenced to suffer, and has con- 

 tinued to suffer ever since. 



Fuchs gives an example of the movement of a seismic 

 centre in the case of the Calabrian earthquake. The first 

 shock commenced near Oppiedo, the second shock com- 

 menced four or five miles farther to the north, and the 

 third shock had its origin five or six miles still farther, 

 near to Girifalco. 



