EARTHQUAKE RISKS

Evening Post, Volume CXI, Issue 38, 14 February 1931, Page 9

EARTHQUAKE RISKS

MUSSOLINI'S DEGREE

After the Italian earthquake of 23rd July, 1930, the Italian Premier, Signor Mussolini, promulgated a building code for the various seismic districts throughout Italy. This specified that the strength required for resisting the horizontal vibration of buildings caused by earthquakes, in the zones of greater severity, must equal one-sixth of the superincumbent weight, in all stories, for buildings. more than about twelve metres in height.' In the zone of lesser activity the ratio is one to eight for buildings more than twelve metres in height, and one to ten for those of lesser height. Tho chief structural lesson from tho Italian earthquake has been stated to be that of the danger of building fragile structures, with heavy floors, roofs ,aud walls, in a region subject to earthquakes. The extra cost of building structures that would bo far safer, most of which would withstand an earthquake of greater intensity than tho recent shock, would be very little beyond that involved in: (1) Competent engineering advice; (2) going farther afield to obtain good mortar sand; (3) proper admixture of cement with the limo in the mortar; (4) use of strong girders for supporting floors and roofs; (5) proper ties of steel rods, for resisting the arch-thrust; (6) use of reinforced concrete where its cost is permissible. .. . Tho greatest lesson of all is that of the danger of weak heavy walls, composed of poorly shaped stones, laid up in weak limo mortar, and of weakly supported heavy floors and roofs, in-a country of frequent violent- earthquakes. But tho types of buildings erected in rural Italy are hardly comparable to thoso built in other countries. ' ' ' ■ It has been suggested that one of tho most instructive researches that the Italian Government might undertake would bo that of establishing and repeating several linos of precise levels across the country. These might givo important warnings of impending earthquakes, by indicating a very small tilting of the earth, indicating the bend that precedes fracture as they have been found to give in Japan. It is well known that the land along the coast of the Adriatic coast north of the River Po has been sinking slowly for hundreds of years.