244 SCIENCE PROGRESS 



same towns are repeatedly destroyed, either entirely or in 

 part. For instance, Reggio, Monteleone and Catanzaro have 

 been rebuilt several times ; also Antioch, Tripolis and Damascus 

 in Asia Minor ; Erivan, Tabriz and Meshed in Persia ; and 

 Cumana and Caraccas in Venezuela. Volcanic earthquakes, 

 however, such as those of Ischia, may be concentrated for 

 successive centuries within the same small areas. 



To a very considerable extent, the destructiveness of a 

 shock depends on the nature of the ground, so that within the 

 area of a single town there may be many variations in the 

 amount of damage to the buildings. In the city of Tokyo, 

 there are two well-defined districts, one consisting of hard high 

 ground, the other of low soft ground, the intensity of the 

 earthquakes being much less on the former than on the latter. 

 In towns that are only partially destroyed, the distribution of 

 the damaged buildings illustrates the same law. At Charleston 

 in 1886, the injury to houses was greatest on low-lying " made " 

 land ; and this was also the case twenty years later at San 

 Francisco and in 1908 in Sicily and Calabria. Even in the 

 non-destructive shocks of this country, local variations of 

 intensity depending on the nature of the ground are frequently 

 observed. Shocks are much less strongly felt in houses built 

 on the hard rocky ground of Malvern and Stirling than in 

 those situated on the plains at the hill-foot. 



Important as the nature of the site undoubtedly is in an 

 earthquake country, the magnitude of the death-rate is affected 

 still more by the structure of the buildings. The defects which 

 are chiefly responsible for high death-rates could hardly be 

 illustrated more clearly than in many of the older cities of 

 Italy. In the Basilicata, the mediaeval towns and villages are 

 almost universally perched upon the summits and steep slopes 

 of hills and their spurs, the houses being built at the very 

 edge of precipices. The streets are narrow, sometimes only 

 five feet, not often more than fifteen feet, in width. The houses 

 are generally built of limestone and brick but the limestone is 

 seldom well-bedded and therefore cannot be raised in long flat 

 blocks. The mortar is poor from containing too much lime and 

 from the lack of a proper quality of sharp sand. Thus, even 

 the best walls, according to Mallet, consisted of " a coarse, 

 short-bedded, ill-laid rubble masonry, with great thickness of 

 mortar joints, very thick walls, without any attention to 



