SEISMIC WAVES.

Hauraki Plains Gazette, Volume XXXIV, Issue 4602, 17 September 1923, Page 2

SEISMIC WAVES.

AN INTERESTING STUDY. EARTHQUAKE SEAMANSHIP. The terrible consequences resulting from the Japanese earthquakes of the past few days have assisted iu emphasising New Zealand’s comparative freedom from serious damage tc property from this cause, despite what has been said in the headlined of certain newspapers in AustraliaMinor shakes every now and again,' hoy,’ever, keep the danger ever before New Zealanders, and there are examples to be obtained from the record of the past sufficiently serious to indicate that New Zealand’s position is hot quite as secure as most people would desire, The Dominion Nautical Advisor (Captain G. S. Hooper,), in the course of a. conversation with a representative of the “Post” produced tangible evidence of this fact when recalling happenings as far back as 1868. The reporter was also shown an interesting report prepared by the United States Hydographer, in whicn reference is made to the highly important question of earthquake seamanship, a phase of nautical work in which Ne.w Zeaalnd seamen have veiy fortunately had little experience. In view of the happenings of sixty years ago, however, a knowledge of .such seamanship may prove of immense value. Much damage was caused in New Zealand in 1868, as .the result of the' action of what are te.med a seismic waves. At Lyttelton on August 15 of that year, at 3.30 a.m„ the water receded from the harbour, rushing past shipping in the stream and at anchor near the entrance at a great velocity. An hour later the end of the breakwater, where the depth usually was flften feet # became dry. At 4.30 am. the water returned in the form of a loud roaring wave eight feet high, rushing up the harbour. In twenty minutes it rose to within three feet of the railway level—three feet above t,he highest springs. Lyttelton harbour was quite dry from the wharf .to Officers’ Point, and vessels were lying on their sides. The immense incoming wave tore vessels from their wharves and did much damage. Similar, though diminishing. oscillations continued for two days, normal conditions reappearing on the fourth day. Simultaneously, tidal disturbances occurred at Bluff, Otago Harbour, Oamaru, Timaru, Nelson, Wellington, Napier, Opotiki an! Mongonui. At. Oamaru the tide fel’ eight feet below low water, and changed its perpendicular height fifteen feet at intervals of fifteen minutes. Timaru experienced a sudden rise of six feet, and a fall four minutes later, to an abnormally low level. At Nelson the tide was reported to have entered over the Boulder Bank, and at Wellington, Napier, and Opotiki a wave six feet high entered the harbour. The disturbance was also felt at Sydney and some damage resulted at Chatham Islands.