THE JAMAICA EARTHQUAKE 403 



the earth. A prompt repairing of the breaks in these two systems 

 undoubtedly saved the city from an outbreak of destructive pestilence. 



Arches in buildings apparently withstood the shock to a notable 

 degree, whether transverse or parallel to the line of the earthquake 

 motion. Generally when built in houses they preserved the parts 

 around them. The Institute, a building in which some two hun- 

 dred delegates had assembled in the first session of the West Indian 

 Agricultural Conference, is built on two lines of arches at right angles 

 to each other. The Institute was damaged, but withstood the shock. 

 The great destruction of brick buildings in Kingston was doubtless due 

 to the fact that poor mortar and dry bricks were used in the construc- 

 tion. The mortar generally appeared to be rather porous and usually 

 the cracks in the wall followed the mortar, though at Up Park Camp, 

 where the bricks were laid in cement mortar, the cracks passed through 

 the bricks. 



The streets were narrow (Figs. 4 and 5), so that the falling wall of 

 even a two-story building would block the street, and many persons 

 escaped from falling buildings only to be crushed in the choked narrow 

 streets. A cement floor may help preserve a building from destruction. 

 In many cases it could be seen that if the floors had been well tied to 

 the walls and the walls themselves held at the corners, a great lessening 

 of the destruction would have resulted. On account of the white ants 

 foreign woods are, unless creosoted, difficult to use, but some frame 

 houses showed but the slightest effect of the earthquake shock. The 

 ' barrack ' or ' noggin ' structure, much used in earthquake countries, 

 apparently suffered nearly as much as other brick walls. 



Jamaica lies in a region of great differential relief and consequent 

 stress. The earthquake was confined in its area of greatest destruction 

 to small limits upon alluvial detrital material, where the amplitude was 

 increased to bring about this effect, varying with the heterogeneity of 

 material. The origin of the shock was comparatively shallow and the 

 earthquake was local in character. While there was a general distinct 

 rotary motion induced by two components of the vibrations, the major 

 component came from a westerly direction. There were few evidences 

 of sea waves, but there was a unique zone of Assuring and subsidence 

 about the harbor of Kingston. Finally, the disasters at San Francisco, 

 Valparaiso and Kingston should teach the lesson that in the case of 

 cities located in a danger zone (where there are many recurring shocks 

 of slight degree) , there is always a possibility of the coming of a disas- 

 trous shock ; that certain types of buildings should be built and streets 

 laid out with that possibility in mind ; that water, sewage and lighting 

 systems should be planned in sections, and that as far as possible a city 

 should not be located nor large edifices erected upon uncompacted rocks 

 and soils. 



