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EARTHQUAKE REPORTS. Symbols, Notation, etc. 1. Character ol the earthquake : — d Local shock perceptible at station, its intensity being expressed on the Rossi-Forel scale thus :RF 1, &c. v Near shock (origin less than 9°, or 1,000 kilometres, distant). r Distant shock (origin from 9° to 45°, or 1,000 to 5,000 kilometres, distant). u Very distant shock or teleseism (origin more than 45°, or 5,000 kilometres, distant). 2. Phases of the seismogram [each of the following symbols may denote — (a) the phase itself; or (b) the time of arrival of the first waves of that phase at the station ; or (c) the time of transit of those waves from the origin in seconds : there will be no ambiguity]:— P .. .. .. .. Longitudinal waves, direct (first phase or first preliminary tremors). PR (or PR,), PR 2 .... PR n • • Longitudinal waves, rctlceteil once, twice, n times, at the earth's surface. S .. .. .. .. Transverse waves, direct (second phase or second preliminary tremors). SR (or SR,), SR 2 .... SR„ .. Transverse waves, reflected once, twice, n times, at the earth's surface. Sl' .. .. .. Interval (in seconds) between the arrival of the P waves and the S waves. I'S .. .. .. .. Waves changed from longitudinal to transverse oscillation, or vice versa, through reflection at the earth's surface. L .. .. .. .. Long waves (chief phase or principal part; regular waves). Lj, Lj L n .. .. Successive series of L waves. Lj .. .. .. .. Long waves passing along the major arc of the great circle through the epicentrum and the observatory. (Repeats of L or Lj after a circuit or circuits of the earth are noted in the " Remarks.") M .. .. .. .. Greatest motion in the chief phase. Mj . . .. .. .. Maximum of the Lj waves. C .. .. .. .. Tail or end portion. F .. ■• .. .. End of discernible movement, 3. Nature of the motion : — ' e ! (Beginning of the motion, used either alone or with one of the symbols in , , f '' ''12 denoting phase, e gradualj " l T (period) . . . . . . Time of one complete oscillation (to and fro). A .. .. .. .. Amplitude of the motion, measured from the median line, in millimetres (mm., as shown on the seismogram), or in mikrons (p, actual movement of i In- ground): (/* = L/1000mm.). Ae .. • ■ .. • • E—W component of A. A n .. .. .. .. N-S component of A. A v ■ • ■■ •• •■ Vertical component of A. 4. General: — Time .. .. .. G.C.M.T., Greenwich civil mean time, 0h.0r24 h. = midnight. E (epiccntrum) .. .. Position of epicentre. O (origin) .. .. .. Time of shock at origin. 0 .. .. .. .. Latitude. \ .. .. .. Longitude from Greenwich. A .. .. .. .. Distance from epicentre in degrees (°) or in kilometres (kms.). 5. The Observatory : — (a.) Its position : Lat. 43° 31' 48" S., long. 172° 37' 13" E. Its height, above mean sea-level : 8 met res (25 ft.). (b.) The kind of seismograph : Milne No. 16 (ordinary boom). How installed : Boom N.-S. Natural period : 10 seconds. Magnification : 8. Damping : Nil.

Earthquake Reports.

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'ime is [reenwicl civil mean time ; it is given in lours, minu ites, am set;. om Is. 01 i. or i. = mi. ".« it. Amplitude. No. Date. Character. Phase. Time. G.C.M.T. Boom Period. A e . Remarks. I 1920. Jan., 1 P M P n. M. S. 3 III IS :s 11 is 12 21 IS 12 21 36 12 23 12 12 21 12 12 25 06 12 41 12 3 02 51 3 04 54 21 30 24 21 32 IS 21 35 IS 21 36 00 2! 10 30 21 50 24 21 54 18 21 58 24 19 46 21 19 48 21 19 50 12 19 53 00 03 36 00 03 43 12 04 13 48 04 17 30 12 32 00 12 37 30 s. MM. 1 16 0-2 Slight microseisms in evidence. 2 1 L M M P M P 4-0 2-4 ? Microseism. ?S. ? SR,. 3 11 0-4 4 22 5 6 », 29 29 L M ?SR L M S SR., I." M PR t ? S L M r, M 2-0 1-4 Slight microseisms evident. Feh., 3 1-0 3 0-2 Slight microseisms evident. 1-5