232 



EARTHQUAKES. 



In Tokio, which is built partly on a flat plain, partly 

 in valleys denuded from a low tableland, and partly on 

 the spurs of the tableland itself, the distribution of 

 earthquakes is a subject yet requiring attention. Some- 

 times it has happened that persons in one house have 

 been sufficiently alarmed to escape into the open air, 



Earthquake of March, la^.l" 1873, 

 (P.A.Serpieri) 



Fig. 34. 



Subsequent radial disturbance 



% 



whilst others, not more than a mile distant, have not been 

 aware that the city had been shaken. 



Extension of earthquake boundaries. — Natural ob- 

 structions which may be sufficient to retard small earth- 

 quakes may in certain instances not be found sufficient 

 to retard the larger disturbances. Thus the shocks of 



