H.—34

62

reached at New Plymouth on the 7th March, and near the Hermitage, Mount Cook, on the 25th March. The lowest maximum intensities occurred in May and October, when no shocks above force 4 were experienced. Table 111 represents an attempt to discover whether earthquakes are more likely to occur at one time of the day than at another. The total figures for the year 1928 show that the earthquakes were almost evenly distributed throughout the day. There was a slight preponderance of morning over evening in the earthquake numbers, but this only amounted to 6 per cent. Table IV gives the number of earthquakes whose maximum intensity fell in different numbers of the Rossi-Forel scale. The table shows that 90 per cent, of the earthquakes in 1928 were of intensity sor under, and 65 per cent, of intensity 4or under. Only two shocks reached intensity 8, and none exceeded 8. A map has been prepared to show the approximate epicentres* of the most outstanding earthquakes in 1928. The epicentres were determined by reports from observers in conjunction with data from the seismograms of the Dominion Observatory, Wellington. The small inset map shows the epicentres in the south-west Pacific. Those outside New Zealand have been determined from the seismograms at Wellington and Suva in conjunction with seismological reports from Apia and Melbourne.

Table I. —General Summary, 1928.

New Zealand Mean Time. | Maximum Where felt. Force, Day. Hour. R '" F - Soale ' Jan. 11 2 Dannevirke .. .. .. .. .. .. 4 15 12 Opotiki and Gisborne .. .. .. .. .. 3 18 23 Dannevirke .. .. .. -.. .. .. 4 25 17 Hawke's Bay district .. .. .. .. .. 4 27 19 Cheviot .. .. .. .. .. .. .. 5 30 00 Wairarapa district . . . . . . .. .. . . 5 Feb. 5 1 Whakatane .. .. .. .. .. .. 5 5 12 Opotiki .. .. .. .. .. .. .. 4 7 13 Waiau .. .. .. .. .. ., .. 3 11 12 Wairoa .. .. .. .. .. .. .. 3 13 18 New Plymouth .. .. .. .. .. .. 3 16 2 East Cape district .. .. .. .. .. .. 6 19 7 New Plymouth .. . . . . .. .. . . 4 19 14 Opotiki .. .. .. .. .. .. .. 3 23 21 Whakatane .. .. .. .. .. .. 5 27 23 Taihape .. .. .. . . . . .. . . 5 Mar. 3 2 East Cape and Bay of Plenty districts .. .. .. 6 5 20 Wairoa .. .. .. .. .. .. .. 2 6 11 Balclutha .. .. .. .. .. . . .. 4 7 6 Western portion of North Island from Kawhia southwards, and Collingwood in the South Island 8 10 Waitara and New Plymouth .. .. .. .. 3 9 11 Wellington .. .. .. .. .. .. 4 9 13 Southland .. .. .. .. .. .. 4 10 10 Nelson Province .. .. .. .. .. .. 6 16 7 Manawatu and Wellington districts . . . . .. . . 4 18 23 Queenstown .. .. .. .. .. .. 3 19 13 Havelock North .. .. .. .. .. .. 3 23 8 Paradise .. .. .. .. .. .. .. 3 23 13 Paradise .. .. .. .. .. .. ., 3 25 9 Westland, Otago, and Southland . . .. . . .. 8 25 14 Hermitage .. .. .. . .. .. 3 25 23 Queenstown . . . . . . .. . . . . 3 31 4 Wairoa .. . . .. . . .. .. . . 3 April 6 | 7 Hawke's Bay . . .. .. .. .. .. 5 18 15 Tarawera .. .. .. .. .. .. .. 3 21 14 Tarawera .. .. .. . . . . .. . , 3 28 22 Pahiatua .. . . .. .. . . . . . . 4 May 2 7 Nightcaps .. .. .. .. .. . . 4 9 9 Napier . . .. . . .. . . . . . . 3 12 4 North Island from Woodville southwards . . . . . . 4 17 11 Opotiki .. .. .. .. ., .. .. 3 27 21 Bay of Plenty district .. .. .. .. .. 4 28 4 Opotiki .. .. .. .. .. .. .. 3 * The epicentre of an earthquake is the point on the earth's surface directly above the origin.