CURIOUS PAIR OF "QUAKES."

Dominion, Volume 7, Issue 1886, 21 October 1913, Page 7

CURIOUS PAIR OF "QUAKES."

THE SEISMIC RECORDS. ' (By Tolesn-nph—Pr<*' Association.! • Chrlstchuroh, October 20. A record of ft very largo earthquake, presumably of origin near the New Hebrides, was obtained at thp Christchurch Magnetic Observatory on the evening of October 17. The motion, commenced at Ohristehurch at 7.44 ?.m., a second jjhaso commencing at .48. The first maximum of long waves was at 7.51 p.m. New Zealand time, tho Bomi-amplitudo of fclio boo_m_ motion •being very large—eighteon millimetres. ; A second maximum, with a semi-ampli-tude of six millimetres, occurred at 7.45, and a second series-of long period! waves wa3 registered from 8.9 p.m. to 8.12, and tho last recorded waves due to the earthnualso ended at 10.19 p.m. on the next day. A further'earthquake was recorded, commencing at 8.51 a.m. New Zealand time. Largo waves commenced at 8.53 a.m., with maximum nt 8.55, corresponding to 2.2 millimetres, semi-amplitude of boom motion, the large waves ending at 8.57 a.m., and the subsequent tremors ending _at 9.23. This shook probably had its orifrin in Now Zealand. The records exhibit a curious pair of largo quakes, occurring within a fewhours of each other October .11, and, possibly, of similar origin to the largo New Hebrides earthquake. Tho first of these was recorded locally from 13hr. 17min. Bsco. to 15hr. 42min., with a maximum of long waves at 13hr. 28min. Ispc. , generating four millimetres semiamplitude of boom motion. The sccond was recorded from lohr. 50min. to lGlir. 52min.., with a maximum of long waives at 15hr. 59min. ssec., generating 5.5 millimetres semi-amplitude of boom motion. The commencement of tho second shock is 'uncertain to a minuto or two, hut the great similarity of the successive phases places beyond doubt tha identical orgin of tho two shocks.