NOTES OF EARTHQUAKE.

Otago Witness, Issue 2722, 16 May 1906, Page 12

NOTES OF EARTHQUAKE.

1 A correspondent .sends -us' the iollowjng suggestions he culled some time -ago wheu reading come wocks ,on seismology that appear worthy of 'being bprne in , mind by the .public lauthordties And , pro-, pertv -owners .at foe present time, and remarks: '"y>our iacile apd .sapient writer j 'Civis' in hie -first v .Passing Note' -of j Saturday jnuat have had similar reflec- | tions in his ,mjnd." Tho destruction of I .produced by earthquakes is .not I irregular. The a&rjbquakes in Jajsan in 1 1891 destroyed betivoeh Nagoya and Gifu ' a series of villages that had once jlormed I what .was practically, a cqntirujous street j more than ,25 .miles in length, and .all that • remained were two long lines of dobxis." Generally speaking, all the 'buildings 1 yielded on "the s.de where, in consequence of windows and doore, they were the weakest. The same ©ft'octa were noticed by Darwin in the after-effects of the jcrueat earthquake ,at Coucepcicn in 1835. I Later, in 1679, at Tokio, similar results i were noted. Some occurred .at Belluno ;in 1873. Mallet recorded similar damages after the Neapolitan earthquake of 1857. The Imperial College of Engineering in Tokio in 1880 conducted <a series of observations -to see how these damages could be mitigated and provided for beforehand. .They found that buildings designed with cracks and joints between those parts whioh were likely to have different periods of vibration .were «iore stable than others. The- alsq indicated that roofs with >a moderate pitch ,stood better than those .with the steepest I Arches tand -openings jn heuyy walls, i whioh ,as j» rule are .generally .strengthened to deal with vertical thrusts, .require in | .earthquake -areas to be specially made ..strong enoi^gh to resist horizontal -.pulls. Long chimneys through roofs -should pa3s fneely through without being tied to or -coming in -contact with any of the jnain. timbers. Over rigidity of buildings by firmly joining, thorn together by bolts an,d angle irons is a mistake iv places subject to seismic shocks. High buildups and heavy overhaQgirjg cornices aro In the 1868 . earthquake in San .Francisco this was especially noted. Unnecessarily .'heavy roofs on weak fcamewocks should be avoided. Instead -of heavy .plaster .mouldings for internal decorations use papiermache or embossed zinc ones. *In Wellington in 1855 the brjck buildine;.s on tho sides pf the hills sufferec] more than those on the flat. At San Francisco ,and Arequipa in 1868 end at Messina the opposite was noted. Experience has shown that buildings with ,a basement surrounded by open ; areas are less liable to destruction than .those rigidly tied to the surface. j Sites for heavy Buildings should not be selected in soft ground, slopes, or scarps. i The foundations , should be deep, and have a free basement; Jowest .walls should be especially strong and well bonded- tsut the iron or steel bends must ,act uoon large surfaces .aud be interlaced. Reinforced concrete "buildings are strongly believed in for these .areas. Large -^ater or sewage concrete conduits reguine to be of the reinforced tj'pe, .and the segments, in addition to the ordinary spiral ami zonal ste»l or iron ribs, requite to be laced together by longitudinal bonding rods, such as are used in the .numerous types arf reinforced concrete work. In ; many parts adobe buildings are preferred. .In most areas that have, been subject to seismic shocks the are vory strict in their building regulations to* this end. This is especially so in Japan, Manila, and many parts of Italy. More damages have ensued from thefires which have succeeded earthquake shocks than from the shocks themselves.