Australian seismological report 1980

David Denham & P. J. Gregson

Bureau of Mineral Resources, Geology & Geophysics

in* REP 6

BMR F15BLICATI0MS COMPACTUS (LENDING SECTION)

Department of Resources & Energy BUREAU OF MINERAL RESOURCES, GEOLOGY & GEOPHYSICS

AUSTRALIAN SEISMOLOGICAL REPORT 1980

Compiled by David Denham & P.J. Gregson

(Division of Geophysics)

AUSTRALIAN GOVERNMENT PUBLISHING SERVICE CANBERRA 1984

REPORT 252

DEPARTMENT OF RESOURCES & ENERGY

Minister: Senator The Hon. Peter Walsh Secretary: A. J. Woods

BUREAU OF MINERAL RESOURCES, GEOLOGY <Sc GEOPHYSICS

Director: R.W.R. Rutland

ABSTRACT

The level of seismicity in Australia during 1980 was comparatively low. Of the 100 earthquakes of magnitude 3*0 or greater that were located during the year, only two had magnitudes of 5*0 or greater - the Offshore-Fremantle and Cadoux earthquakes in December of magnitudes 5»2 and 5*0 respectively.

During 1980 the seismograph coverage was improved by the opening of three permanent stations, at Boondooma Dam in Queensland, Mount Gambier in South Australia, and Nanutarra in Western Australia. At the end of the year 68 seismographs were operating throughout the continent.

Three earthquakes were recorded on strong-motion accelerographs -these were all in Western Australia. The maximum acceleration recorded was 109 cm.s~2 at a site near Meckering, WA, from a magnitude 2.3 earthquake which occurred close to the accelerograph.

On a world scale the largest earthquake during 1980 occurred near, the Santa Cruz Islands. It had a surface-wave magnitude of 7*9 and generated tsunamis throughout the region. The most destructive earthquakes were those in Algeria on 10 October when a 7*3 MS event killed 5000 people, and in southern Italy on 23 November when a 6.8 MS earthquake killed 3100 people.

Published for the Bureau of Mineral Resources, Geology & Geophysics by the Australian Government Publishing Service

©Commonwealth of Australia 1984

ISBN 0 644 03524 2 ISSN 0084-7100

Printed by Graphic Services Pty Ltd, 516-518 Grand Junction Road, Northfield, S .A . 5085

Contributors

Contributors to this publication are listed below according to the information furnished or service performed: Hypocentres and magnitudes

D. Denham, BMR, Canberra, ACT G. Gibson, Preston (now Phillip) Institute of Technology, Bundoora, Vic. P.J. Gregson, BMR, Mundaring Geophysical Observatory, Mundaring, WA C. Krayshek, Research School of Earth Sciences, Australian National

University, Canberra, ACT. R. MacDougall, University of Adelaide, Adelaide, SA R. Nation, University of Adelaide, Adelaide, SA National Earthquake Information Service, US Geological Survey, Boulder, USA. E.P. Paull, BMR, Mundaring, WA J. Pongratz, University of Tasmania, Hobart, Tas. R.S. Smith, BMR, Canberra, ACT J.P. Webb, University of Queensland, Brisbane, Qld J. Weekes, Research School of Earth Sciences, Australian National

University, ACT International Seismological Centre, Newbury, UK (ISC)

Intensities P.J. Gregson, BMR, Mundaring, WA J.M.W. Rynn, University of Queensland, Brisbane, Qld

Network operations (by institution) Australian National University, Canberra, ACT (CAN) Bureau of Mineral Resources, Geology & Geophysics, Canberra, ACT (BMR) and Mundaring, WA (MUN)

Department of Public Works, Perth, WA (PWD) Preston (now Phillip) Institute of Technology, Bundoora, Vic. (PIT) Queensland Geological Survey, Brisbane, Qld (QGS) Riverview College, Sydney, NSW (RIV) University of Adelaide, Adelaide, SA (ADE) University of Queensland, Brisbane, Qld (QLD) University of Tasmania, Hobart, Tas. (TAU)

Strong-motion data P.J. Gregson, BMR, Mundaring Geophysical Observatory, Mundaring, WA

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CONTENTS Page

INTRODUCTION 1 AUSTRALIAN EARTHQUAKES 1980 • • 2 NETWORK OPERATIONS .. 6 STRONG-MOTION SEISMOGRAPH DATA 18 PRINCIPAL WORLD EARTHQUAKES 1980 18 REFERENCES 23

Appendix: Modified Mercalli Scale 24

TABLES

1. Australian earthquakes 1980 • 9 2. Australian seismograph stations 1980 14 3« Australian accelerographs 1980 17 4* Accelerogram data 1980 18 5» Principal world earthquakes 1980 20

FIGURES

1. Australian earthquakes 1980 .. 3 2. Australian earthquakes 1873-1979 4 3. Isoseismal map of the Ashford Earthquake, NSW

4 September 1980 5 4. Isoseismal map of the Offshore-Fremantle Earthquake, WA

8 December 1980 7 5» Isoseismal map of the Cadoux Earthquake, WA

10 December 1980 8 6. Australian seismograph stations 1980 13 7. Principal world earthquakes 1980 • 19

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INTRODUCTION

This Report provides information on all earthquakes of Richter magnitude 3 or greater that were reported in the Australian region during 1980. It is the first of an annual series to be compiled by the Bureau of Mineral Resources, Geology & Geophysics (BMR) using data provided by various seismological agencies in Australia. Its purpose is to provide information on Australian earthquakes for the study of seismic risk and to answer inquiries from both scientists and the general public.

The Report comprises four main sections: 'Australian earthquakes', which contains a summary of the 1980 seismicity and brief descriptions of the more important earthquakes; 'Network operations', which gives details of the seismographs that operated in Australia during 1980; 'Strong-motion seismograph data' which contains the results of the accelerograph network; and 'Principal World Earthquakes 1980', which lists the largest and most damaging earthquakes.

Throughout the report we refer to magnitudes of earthquakes and intensities caused by earthquakes. These terms are defined below.

Magnitudes

The magnitude of an earthquake is a measure of its size and is related to the energy released at its focus. The magnitude scale is logarithmic; thus a magnitude-6 earthquake produces ground amplitudes 10 times as large, and an energy release about 30 times as large, as a magnitude-5 earthquake.

A rule-of-thumb relation between magnitude and energy is

log E = 4.8 + 1.5M

where E is in joules. A shock of magnitude 2 is the smallest normally felt by humans, and

earthquakes of magnitude 5 or more can cause major damage if they are shallow and close to buildings.

Several magnitude scales are in common usage. Those used in this Report are defined below. Richter magnitude (ML)

ML = log A - log Ao

as defined by Richter (1958, p. 340), where A is the maximum trace amplitude in millimetres on a standard Wood-Anderson seismogram and log Ao is a standard value given as a function of distance (0-600 km). Richter's reference earthquake of ML = 3»0 produces a trace amplitude of 1 mm, 100 km from the epicentre.

If standard Wood-Anderson instruments (Anderson & Wood, 1925) are not available an equivalent Richter magnitude can be determined by correcting for the differences in magnification (see Willmore, 1979, para. 3*1•1)•

Surface-wave magnitude (MS)

The surface-wave magnitude is normally applicable only to shallow earthquakes in the distance range 20-160 degrees, and in the period range T = 20 + 3 s. When these conditions hold, MS values are calculated from the IASPEI T1967) formula:

MS = log (A/T) + 1.66 log A + 3*3

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where A is the ground amplitude in micrometres, T is seconds, and A is the epicentral distance in degrees (see Bath, 1981).

Body-wave magnitude (mb)

mb = log (A/T) + Q (A,h)

where A is the maximum mean-to-peak ground amplitude in microns of the P, PP, or S-wave trains, T the corresponding wave-period (seconds), and Q (A,h) a depth/distance factor. The Q factors were derived by Gutenberg (1945) and are given by Richter (1958, pp. 688-689).

Duration magnitude (MP)

MD = a log t + bA + c

where t is the length of the earthquake coda in seconds, A the distance from the epicentre, and a, b, and c are constants for a particular recording station.

Further information on magnitudes is available in McGregor & Ripper (1976), Bath (1981), and Denham (1982).

Intensity

Intensity, as applied to earthquakes, represents a quantity determined from the effects on people, buildings, and the Earth1s^surface. In this report we use the Modified Mercalli Scale (MM) as amended by Eiby (1966) for New Zealand conditions and listed in the Appendix. Essentially the MM scale is a subjective assessment of how severely the earthquake was felt and of the damage that was caused at a particular place. Some earthquakes are large enough to be felt over a wide area and an isoseismal map can be prepared. Such maps indicate in detail the extent of the shaking. They are prepared mainly from information compiled from questionnaire canvasses, newspaper reports, and personal interviews and inspections.

During 1980 two earthquakes were large enough for isoseismal maps to be prepared (Figs. 3 and 4).

AUSTRALIAN EARTHQUAKES 1980

Earthquake activity in the Australian region during 1980 was comparatively slight. Figure 1 shows the distribution of all located earthquakes having a magnitude of 3 or greater that occurred during 1980, and, for comparison with longer-term seismicity patterns, Figure 2 shows the distribution of magnitude-4 and greater earthquakes for the period 1873-1979* Table 1 lists the hypocentral parameters for the 1980 earthquakes.

The Southwest Seismic Zone remained one of the most active parts of Australia and 110 earthquakes were located there during 1980. Of these, two were greater than magnitude 4.

Twelve earthquakes were located in a zone between 100 and 300 km northwest of Broome (near 17°S, 120°E), the largest having a magnitude of 4.3*

South Australia was seismically quiet. Only two earthquakes had magnitudes greater than 4 during the year. The largest (ML = 4.2), took place beneath Eyre peninsula and the other (ML =4.1) near the North Flinders Ranges.

In southeastern Australia three earthquakes with magnitudes greater than 4 were located. The two largest of these (both ML = 4.2) took place near Ballarat and in the South Tasman Sea respectively. In eastern Australia an earthquake of magnitude ML = 4*3 took place near Ashford in northern New South

•ink

Fig. 1. Australian earthquakes, 1980, having magnitudes 3.0 or greater.

I

Fig. 2. Australian earthquakes, 1873-1979, having magnitudes 4.0 or greater. 2 4 / A / 4 6 - t

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DATE : 4 S E P T E M B E R 1980 T I M E : 21 :05 :44 .79 UT M A G N I T U D E : 4.5 M L (CAN) 3.5 M l l W I V ) EP ICENTRE : 29 .06°S 150.83°E DEPTH : Crustal

A EP ICENTRE I V Z O N E INTENSITY D E S I G N A T I O N (MM)

4 E A R T H Q U A K E FELT (MM) o E A R T H Q U A K E NOT FELT

3.7 M L (I)

2 4 / H 5 6 / 7

Fig. 3. Isoseismal map of the Ashford Earthquake, NSW, 4 September 1980.

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Wales. It was large enough to be felt over a significant area and an isoseismal map is shown in Figure 3« The affected area covered about 4000 km^ with the zone of maximum intensity, MM = 5, being a few kilometres north of Wallangra. Minor damage was reported from a property about 10 km northwest of Wallangra where small objects and vases were overturned (MM = 5-6). Three further reports from the Wallangra district and two from Ashford noted displacements of small objects and pictures (MM = 5)«

This earthquake generated a significant aftershock sequence. Through the month of September 1980 following the main shock, 26 felt reports related to 15 aftershocks were received. Five of these aftershocks were able to be located. An additional seven aftershocks were recorded instrumentally but not reported as being felt. In all a total of 22 aftershocks are known to be associated with this earthquake.

The two largest earthquakes during 1980 occurred in Western Australia - a magnitude-5 earthquake in the Southwest Seismic Zone near Cadoux and a magnitude-5•2 earthquake beneath the ocean 150 km west of Fremantle. Both were felt near Perth. The isoseismal maps are shown in Figures 4 and 5«

The Offshore-Fremantle earthquake of 8 December occurred in an area where no previous earthquake had been reported. The maximum intensity - MM V - was experienced at Fremantle and Cape Naturaliste. Interestingly, felt intensities in the Perth region were generally higher to the east of the Darling Fault.

The maximum intensity from the 10 December Cadoux earthquake was MM VI and the earthquake was felt with an intensity of MM III in Perth. The epicentre of the earthquake was at most only 10 km from the magnitude-6.2 Cadoux earthquake of June 1979 that caused damage estimated at nearly $4 million.

NETWORK OPERATIONS

The number of permanent seismographs operating in Australia has gradually increased since the late 1950s when World Wide Standard Seismographs were installed at Adelaide (SA), Charters Towers (Qld), Hobart (Tas.) , Mundaring (WA), and Riverview (Sydney, NSW). Figure 5 shows the locations of the permanent stations that operated during 1980, and Table 2 gives the co-ordinates of the stations and indicates the type of seismograph. Three new stations were commissioned during the year: Boondooma Dam in Queensland, Mount Gambier in South Australia, and Nanutarra in Western Australia. Although these stations filled large gaps in the recording network, the coverage was still inadequate in northern New South Wales, Queensland, and parts of Western Australia.

Regional epicentres were located by the main operating institutions listed on page iii and BMR co-ordinated these to provide the list in Table 1. The BMR also maintains the definitive Australian earthquake data file and provides basic earthquake data for the Australian region on request, to scientists, insurance companies, engineers, and the general public.

200km — i

• I V

DATE : 8 D E C E M B E R 1980 T I M E : 00 :12 :07 .8 UT M A G N I T U D E : 5.2 M L (MUN), 4.6 M B (GS) EP ICENTRE : 32 .12°S 114.11°E DEPTH : 37km

EPICENTRE Z O N E INTENSITY D E S I G N A T I O N (MM) E A R T H Q U A K E FELT (MM) E A R T H Q U A K E NOT FELT

Fig. 4. Isoseismal map of the Offshore-Fremantle Earthquake, WA, 8 December 1980

2 4 / O W A / l

200km

A I V

DATE : 10 D E C E M B E R 1980 T IME : 04 :35 :05 .6 UT M A G N I T U D E : 5.0 ML (MUN), 4.0 M B (GS) EPICENTRE : 30 .73 S 117.15°E DEPTH : 13km

EPICENTRE ZONE INTENSITY D E S I G N A T I O N ( M M ) E A R T H Q U A K E FELT (MM) E A R T H Q U A K E NOT FELT

Fig. 5. Isoseismal map of the Cadoux Earthquake, WA, 10 December 1980. 2 4 / W A / 4

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TABLE 1. AUSTRALIAN EARTHQUAKES 1980: HYPOCENTRAL PARAMETERS

DATA DATE ORIGIN (UT) LAT°S LONG°E DEPTH MAGNITUDE N* SOURCE *

mo hr mn sec (km)

BMR 80 01 16 02 49 19.1 39.519 145.599 1 3.6 ML 28 CAN 80 01 24 09 30 43-0 38.640 148.550 0 3.1 ML 8 MUN 80 02 06 17 17 11 .5 30.820 117.230 3 3.2 ML 5 BMR 80 02 08 04 41 45-5 19.850 152.540 0 4.5 ML 3 BMR 80 02 08 19 40 50.3 24-71 141.62 0 4.0 MI 7 ADE 80 02 09 14 33 06.1 28.822 138.828 18 3.1 ML 7 MUN 80 02 09 18 50 52.2 19.780 122.740 8 3.8 ML 4 MUN 80 02 10 01 32 44 19-780 122.740 8 3.0 ML 1 BMR 80 02 12 22 41 50.2 23-020 130.099 0 3-8 ML 4 ADE 80 02 15 23 51 42.6 31.488 138.259 12 3.4 ML 10 CAN 80 02 17 16 39 42.4 34.890 145 510 12 3-1 ML 6 CAN 80 02 28 12 07 09-2 34.030 147.570 14 3.0 ML 13 CAN 80 03 03 10 30 28.0 38.060 150.300 0 3.1 ML 10 MUN 80 03 08 00 51 38.3 31.130 124.410 19 3.5 ML 3 CAN 80 03 10 04 31 35.1 34.250 147.480 16 3.1 ML 12 MUN 80 03 15 07 09 47.8 18.770 121.640 0 4.7 ML 13 MUN 80 04 01 15 22 02.2 17.170 123.790 0 3.6 ML 6 MUN 80 04 01 18 47 53.9 17.390 120.370 0 3.7 ML 5 MUN 80 04 01 18 48 08.4 17.760 120.740 37 3.9 ML 4 MUN 80 04 02 17 11 52.3 16.630 120.310 0 4.0 ML 6 CAN 80 04 04 11 42 29.0 35.970 144.080 0 3.7 ML 8 MUN 80 04 05 04 58 38.0 30.870 117.160 5 3.1 ML 5 BMR 80 04 06 00 51 35.0 28.720 149.380 0 3.9 ML 3 MUN 80 04 09 05 42 17.9 17-220 118.790 0 3-9 ML 6 ADE 80 04 15 00 38 04.8 33.263 137.030 31 4.2 ML 14 MUN 80 04 19 07 44 38.6 19.080 113.450 37 4.7 ML 8 ADE 80 04 22 01 24 45.9 32.027 138.722 12 3.4 ML 20 CAN 80 04 24 04 17 01.0 33.760 150.090 19 3.0 ML 15 CAN 80 04 25 13 58 18.0 36.950 148.270 18 3.0 ML 11 CAN 80 04 26 20 54 24.3 34.640 146.180 12 3.4 ML 11 MUN 80 05 01 12 31 11 .0 18.360 118.310 37 3.0 ML 2

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TABLE 1 (cont.)

DATA DATE ORIGIN (UT) LAT°S LONG°E DEPTH MAGNITUDE N* SOURCE *

mo dy hr mn sec (km)

CAN 80 05 01 21 10 00.8 32.890 149.750 13 3.7 ML 11 MUN 80 05 06 19 06 18.4 17.170 121.060 0 3.5 ML 5 PIT 80 05 10 18 00 47.5 41.140 150.290 0 3.0 ML ADE 80 05 13 21 45 32.2 31.309 138.434 18 3.0 ML 9 CAN 80 05 16 09 41 52.8 33.380 148.390 15 3.3 ML 15 MUN 80 05 19 22 53 43-7 30.820 118.080 9 3.0 ML 5 PIT 80 05 21 04 47 58.5 37.969 146.473 15 3.7 MD 15 PIT 80 05 21 04 48 22.9 37.950 146.510 17 4.0 MD PIT 80 05 21 04 57 28.6 37.950 146.490 16 3.1 MD CAN 80 05 23 17 46 31.3 34.210 149.130 14 3-0 ML 12 CAN 80 05 23 20 26 13.4 34.180 149.130 13 3.0 ML 14 QLD 80 06 01 02 34 19.6 25.50 153.57 0 3.0 MD 1 MUN 80 06 01 07 22 30.3 30.850 117.180 13 3.7 ML 7 CAN 80 06 03 06 28 39.0 38.500 150.000 0 3-5 ML 9 MUN 80 06 03 14 01 37.0 21.260 127.840 0 3.7 ML 9 BMR 80 06 05 14 19 49.4 38.030 148.520 5 4.0 ML 27 BMR 80 06 07 05 15 04.0 22.100 130.260 0 3.4 ML 5 MUN 80 06 12 07 25 52.0 26.890 115.900 37 3.2 ML 5 MUN 80 06 22 08 46 32.4 16.700 120.270 0 3.8 ML 7 MUN 80 06 22 16 20 32.6 17.570 119.900 37 3-6 ML 4 BMR 80 07 02 03 13 51 .2 35.940 149.050 6 4.0 ML 10 ISC 80 07 03 15 22 29.0 10.10 125.96 46 4.9 ML 10 MUN 80 07 04 04 04 22.2 17.770 119.530 37 3-4 ML 3 MUN 80 07 06 04 00 44.0 16.640 120.580 37 3.4 ML 4 CAN 80 07 07 12 30 39.8 34.510 148.950 19 3.5 ML 11 CAN 80 07 19 00 51 56.6 34.580 148.810 16 3.3 ML 13 MUN 80 07 20 06 11 38 21.130 110.000 10 4.2 ML 5 MUN 80 07 26 14 11 38.9 30.820 117.230 6 3-2 ML 6 MUN 80 07 31 12 19 01 19-510 120.960 4-3 ML 8 MUN 80 08 01 20 19 27.5 17.030 119.360 37 4-0 ML 6 MUN 80 08 02 05 31 57 29.410 124.820 3.3 ML 4

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TABLE 1 (cont.)

DATA DATE ORIGIN (UT) LAT°S LONG°E DEPTH MAGNITUDE N* SOURCE *

mo dy hr mn sec (km)

MUN 80 08 02 19 10 22.1 16.710 120.350 37 4.3 ML 7 MUN 80 08 07 20 48 00 29.390 123-580 4.2 ML 8 MUN 80 08 08 02 27 38 27.220 112.30 19 3-3 ML 3 MUN 80 08 17 18 51 02.2 27.460 115.580 37 3.3 ML 8 MUN 80 08 21 15 16 39 17.440 121.170 37 3.1 ML 6 MUN 80 08 24 08 30 19.3 30.820 117.120 15 3.0 ML 4 ADE 80 08 30 14 23 39-9 31.762 139.361 8 4.1 ML 11 MUN 80 09 01 12 48 24.2 30.750 117.180 9 3.0 ML 6 BMR 80 09 04 21 05 44-9 29.126 150.937 1 4.3 ML 15 CAN 80 09 15 00 17 29.7 34.520 149.150 20 3-0 ML 13 CAN 80 09 07 09 55 38.8 34.330 150.810 18 -3.3 ML 12 PIT 80 09 18 05 51 47.5 38.360 145.678 10 3.1 MD MUN 80 10 05 19 26 06.0 33.330 117.760 3-0 ML 3 ISC 80 10 10 01 30 56.7 10.20 124.92 8 4.2 MB 9 CAN 80 10 31 08 36 18 37.970 148.710 0 3.0 ML 6 MUN 80 11 02 18 27 00.9 23.860 113.320 10 3-3 ML 5 ADE 80 11 08 03 17 36.6 32.176 138.595 18 3.1 ML 11 ADE 80 11 13 08 56 16.0 33.739 138.825 19 3.8 ML 12 QLD 80 11 16 00 20 14.4 22.95 152.80 0 3.7 MD 1 MUN 80 11 22 15 30 44 38.380 120.210 10 3.3 ML 5 MUN 80 11 23 19 32 31.5 30.000 123.360 10 3.5 ML 7 MUN 80 11 24 19 54 53 15.720 123.880 37 4.0 ML 6 TAU 80 11 25 14 46 51 .5 43.230 140.620 3.5 ML 7 MUN 80 11 29 13 38 33.0 18.190 125.040 37 3.3 ML 6 MUN 80 12 02 14 51 15.4 17.030 119.950 37 3-9 ML 5 BMR 80 12 07 22 40 31.3 40.410 155.770 0 4.2 ML 25 MUN 80 12 08 00 12 07.8 32.120 114-110 37 5.2 ML 9 ISC 80 12 09 15 18 52 10.51 124.10 17 4.5 MB 15 MUN 80 12 10 04 35 05.6 30.730 117.500 13 5.0 ML 9 ADE 80 12 10 06 24 16.5 31.308 138.702 23 3.1 ML 13

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TABLE 1 (cont.)

DATA DATE ORIGIN (UT) LAT°S L0NG°E DEPTH MAGNITUDE N* SOURCE *

mo dy hr mn sec (km)

CAN 80 12 15 15 06 14.1 32.760 151.410 16 3.4 ML 10 MUN 80 12 19 14 07 41 21.950 126.540 13 3.9 ML 7 MUN 80 12 20 19 23 29 22.000 126.640 10 3-9 ML 7 MUN 80 12 21 13 20 49 22.000 126.570 30 4.0 ML 7 CAN 80 12 23 00 03 33.7 34.590 149.240 8 3-0 ML 4 MUN 80 12 23 14 25 00 21.200 114.550 10 3.0 ML 2 MUN 80 12 24 06 26 34.2 34.690 116.670 3.2 ML 3 BMR 80 12 27 04 40 09-5 35.740 143-690 0 4-2 ML 23

* Code refers to contributors listed on page iii. N - number of stations used to determine hypocentre.

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L 300

600 300 1200 K M

STAT 1ONS OPERATED BY BMR OR J O I N T L Y U1TH ANOTHER O R G A N I S A T I O N

O A D E L A I D E U N I V E R S I T Y

A A U S T R A L I A N NATIONAL U N I V E R S I T Y

H U N I V E R S I T Y OF TASMANIA

2 4 / A / 5

+ PRESTON I N S T I T U T E OF TECHNOLOGY

X U N I V E R S I T Y OF QUEENSLAND

<J> W . A . PUBL IC WORKS DEPT

X QUEENSLAND GEOLOGICAL SURVEY

Fig. 6. Permanent seismograph stations operating in Australia during 1980.

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TABLE 2. AUSTRALIAN SEISMOGRAPH STATIONS 1980

CODE STATION NAME LAT°S LONG°E ELEV (m) OPERATOR* CATEGORY**

QUEENSLAND

BDDM BOONDOOMA DAM 26.1120 151 .4443 320 QGS 1 BRS BRISBANE 27-3917 152.7750 525 QLD 5 CTAO CHARTERS TOWERS 20.0883 146.2550 357 QLD 4,2 ISQ MOUNT ISA 20.7150 139.5533 500 BMR 1 QNN WIVENHOE DAM 27.3507 152.5404 120 QLD 3

NORTHERN TERRITORY

ASP ALICE SPRINGS 23.6786 133.8886 600 BMR 3 MTN MANTON DAM 12.8467 131.1300 80 BMR 1 WB2 WARRAMUNGA ARRAY 19 .9444 134.3525 366 CAN 3

WESTERN AUSTRALIA

KLG KALGOORLIE 30.7833 121.4583 360 MUN 1 KNA KUNUNURRA 15.7500 128.7667 150 PWD/MUN 1 MBL MARBLE BAR 21 .1600 119-8333 200 MUN 1 MEK MEEKATHARRA 26.6133 118.5450 520 MUN 1 MUN MUNDARING 31 .9783 116.2083 253 MUN 2 NAU NANUTARRA 22.4420 115.5000 80 MUN 1 NWAO NARROGIN 32.9267 117.2333 265 MUN 4

WBN WARBURTON 26.1400 126.5780 457 MUN 1

NEW SOUTH WALES AND ACT

BWA BOOROWA 34.4250 148.7513 656 CAN 1 AVO AVON 34.3764 150.6150 532 CAN 1 CAH CASTLE HILL 34.6467 149-2417 700 CAN 1 CAN CANBERRA (ANU) 35.3208 148.9986 650 CAN 1 CBR CABRAMURRA 35-9433 148.3928 1537 CAN 1 IVN INVERALOCHY 34.9650 149-6667 640 CAN 1

TABLE 2 (cont.)

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CODE STATION NAME LAT°S LONG°E ELEV (m) OPERATOR*

JLN JENOLAN 33-8258 150.0172 829 CAN KHA KHANCOBAN 36.2136 148.1288 435 CAN LER LERIDA 34.9344 149.3642 940 CAN MEG MEANGORA 35•1007 150.0367 712 CAN SBR STH BLACKRANGE 35.4250 149-5333 1265 CAN TAO TALBINGO 35.5958 148.2900 570 CAN NAM WAMBROOK 36.1928 148.8833 1290 CAN WER WEROMBI 33.9503 150.5803 226 CAN YOU YOUNG 34.2783 148.3817 503 CAN CNB CANBERRA (BMR) 35=3150 149.3633 853 BMR COO COONEY 30.5783 151.8917 650 BMR STK STEPHENS CREEK 31.8817 141.5917 213 BMR RIV RIVERVIEW 33.8293 151.1585 43 RIV

SOUTH AUSTRALIA

ADE ADELAIDE 34.9670 138.7136 655 ADE CLV CLEVE 33.6911 136.4955 238 ADE EDO ENDILLOE 32.3216 138.0483 300 ADE HKN HAWKSNEST 30.0120 135.1860 171 ADE HTT HALLETT 33-4305 138.9217 708 ADE MGR MT GAMBIER 37.7283 140.5710 190 ADE NBK NECTAR BROOK 32.7010 137.9830 180 ADE PNA PARTACOONA 32.0057 138.1647 180 ADE RPA ROOPENA 32.7250 137.4033 95 ADE UMB UMBERATANA 30.2400 139.1280 610 ADE WKA WILLALOOKA 36.4170 140.3210 40 ADE WSA ¥OOMERA 31.1444 136.8047 180 ADE

VICTORIA

BFD BELLFIELD 37.1767 142.5450 235 BMR TOO TOOLANGI 37.5717 145.4900 604 BMR

2 2

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TABLE 2 (cont.)

CODE STATION NAME LAT°S LONG°E ELEV (m) OPERATOR* CATEGORY**

ABE ABERPELDY 37.7190 146.3890 549 PIT 1 GUL GREENVALE 37.6186 144.9006 188 PIT 1 JEN JEERALANG JNTN 38.3490 146.4140 330 PIT 1 KGD KANGAROO GROUND 37.6988 145-2694 80 PIT 1 LIL LILYDALE 37.6936 145.3424 80 PIT 1 MAL MARSHALL SPUR 37.7483 146.2917 1076 PIT 1 MIC MOUNT ERICA 37.9030 146.3590 805 PIT 1 PAT PLANE TRACK 37.8570 146.4560 771 PIT 1 PNH PANTON HILL 37.6346 145.2709 180 PIT 1 TOM THOMSON 37.8100 146.3480 941 PIT 1 DRT DARTMOUTH 36.5833 147.4917 950 CAN 1

TASMANIA

MOO MOORLANDS 42.4417 146.1903 325 TAU 1 SAV SAVANNAH 41.7208 147.1889 180 TAU 1 SFF SHEFFIELD 41.3375 146.3075 213 TAU 1 STG STRATHGORDON 42.7508 146.0533 350 TAU 1 SPK SCOTTS PEAK 43-0383 146.2750 425 TAU 1 SVR SAVAGE RIVER 41.4888 145.2108 360 TAU 1 TAU TASMANIAN UNIV 42.9097 147.3206 132 TAU 2 TRR TARRALEAH 42.3042 146.4500 579 TAU 1

* Refers to the collaborators listed on page ill. ** 1 . Short period (vertical and/or horizontals), 2. World Wide Standard

Seismograph Station, 3* Array, \* Seismological Research Observatory, 5 . Long and short period seismographs.

TABLE 3- AUSTRALIAN ACCELEROGRAPHS, 1980

LOCALITY LAT S LONG E ELEV (m) FOUNDATION INSTRUMENT TYPE

OPERATOR*

149.163 600 Firm soil/ SMA1 BMR granite

149.043 SMA1 BMR 147.033 600 Dam wall SMA4 WRC 147.033 600 Dam wall SMA1 WRC 147-033 600 Dam wall SMA1 WRC

138.78 Slate & M02 EWSSA schist

138.70 Marl & clay- MO 2 PWDSA 138.608 Alluvium M02 PWDSA

145-97 Quartzite M02 HEC

116.982 200 Alluvium/ M02 BMR granite

117.089 200 Alluvium/ M02 BMR granite

117.002 200 granite MO 2 BMR

116.958 220 Alluvium/ M02 BMR granite

116.169 250 Concrete wall SMA1 PWDWA

128.737 160 Phyllite M02 PWDWA 128.738 120 Rockfill wall M02 PWDWA

New South Wales

Oolong 34-773

Yass 34.830 Hume Weir 36.110 Hume Weir 36.110 Hume Weir 36.110

South Australia

Kangaroo Creek Dam 34*87

Modbury Hospital Admin. Centre

Tasmania

Western Australia

Meckering

Kelly's (ME-K)

Morrell's (ME-M)

Richardson's (ME-R)

Springbettfs (ME-S)

Mundaring Weir(MU-W) Ord River Dam

abutment (KU-A) dam wall (KU-W)

34*83 34*925

42.7'

31.694

31.659

31.608

31 .813

31-967

16.113 16.113

BMR

EWSSA HEC PWDSA PWDWA WRC

Bureau of Mineral Resources, Geology & Geophysics - Canberra or Mundaring. Engineering & Water Supply Department, South Australia. Hydro-Electric Commission, Tasmania Public Works Department, South Australia. Public Works Department, Western australia. Water Resources Commission of New South Wales.

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TABLE 4- ACCELEROGRAM DATA, 1980: PRINCIPAL PACTS

YR MO DY TIME LAT°S LONG ° E ML LOC H/E COM T(S) ACC R DUR (UT) ( s )

80 01 21 1720 31 .66 117.10 2.3 ME-M 4/1 PZ 0.01 1 .0 N 0.01 2.8 4.0 E 0.01 2.9 SZ 0.04 46.0 10.3 N 0.02 88.0 109.0 E 0.02 45-0

80 08 21 1508 31.69 117-03 2.2 ME-K (6)/(5) SZ 0.03 3.4 N 0.03 6.8 10.5 7.1 E 0.03 7.3

80 09 09 0932 31.69 117.03 1.5 ME-K (6)/(5) SZ 0.02 0.8 N 0.02 2.6 3.0 1.8 E 0.02 1 .2

KEY

YR=year, MN=month, DY=Day, UT=Universal Time, LAT=latitude, LONG=longitude, ML=Richter magnitude, LOC=accelerograph location, H/E=hypocentral distance / epicentral distance, COM=component, T(S)=ground period in seconds, ACC=peak ground acceleration (cm.s""^), R=resultant acceleration (cm.s"^), DUR=duration in seconds while ground acceleration remained above 0.5 cm.s"*̂ *

STRONG-MOTION SEISMOGRAPH DATA

For earthquake hazard to be properly assessed it is necessary to estimate how the surface of the earth will respond close to an earthquake. Conventional seismographs overload when strong ground motion is experienced, and special accelerographs are normally used in these circumstances. These instruments only operate when the ground motion reaches a threshold level which activates the recorder.

By 1980 sixteen accelerographs had been installed. These are listed in Table 3« Table 4 lists the principal facts from the three recordings obtained during the year. All three were obtained in the Southwest Seismic Zone of Western Australia and the largest acceleration of 109 cm.s"^ was recorded near Meckering from a magnitude-2.3 earthquake.

PRINCIPAL WORLD EARTHQUAKES 1980

Table 5 lists earthquakes of magnitude 7.0 or greater, and/or damaging earthquakes, that occurred throughout the world during 1980.

The two most disastrous were the earthquake of 10 October in Algeria which killed approximately 5000 people and that of 23 November in southern Italy which killed 3100 people. The world death toll from earthquakes in 1980 was about 8700.

Figure 6 shows the locations of these earthquakes and the numbers of casualties.

20° 0° 60° 120" 180° 120° »0° 20° B A S E D ON 0 /17

Figure 7. Principal world earthquakes 1980, showing numbers of reported deaths.

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TABLE 5. PRINCIPAL WORLD EARTHQUAKES, 1980 (Magnitude 7.0 or greater , or causing damage or f a t a l i t i e s . PAS - Pasadena, BRK - Berkeley, PMR - Palmer, A laska , PAL - P a l i s a d e s , N .Y . , JMA - Japan Meteorological Agency)*

Date Or ig in time

(UT) Reg ion L a t . Long. Magnitude Remarks

1 Jan. 16 42 40.0

7 Feb.

23 Feb

10 49 16.3

05 51 03.2

8 Mar. 22 12 10.3

13 Apr. 18 04 51.3

9 June 03 28 18.9

18 June 17 14 54.5

8 July 23 19 19.8

9 July 20 56 53.2

July 17 19 42 23.2

Azores I s I ands

38.82 N 27.78 W

Macquarle Is land

Kur i l I s lands

6.0mb(USGS) 6.7MS(USGS) 7.2MS(BRK) 6.9MS(PAS) 6.9mb(PAS)

54 53 S 158.8E 6.0mb(USGS) 6.5MSCUSGS) 6.4MS(BRK)

43.53 N 146.75 E 6.3mb(USGS) 7.0MS(USGS)

22.67 S 171.36 E 6.lmb(USGS) 6.7MS(USGS) 6.7MS(PAS) 7.1 MS(BRK) 6.4mb(PAS)

23.53 S 177.27 W 6.6mb(USGS) 6.8MS(USGS) 7.2(PAS)

Western Arizona 32.22 N 114.99 W 5.6mb(USGS) and Mexican

Loyalty I s lands

South of Fi j i

border region

Mindanao, Ph i I i p p i ne I s I ands

Santa Cruz Is lands

Santa Cruz I s lands region

Santa Cruz I s lands

9.47 N 126.66 E

12.41 S 166.38 E

6.4MS(USGS) 6.IML(BRK)

5.8mb(USGS) 6.8MS(USGS) 7.2MS(BRK) 6.8MS(PAS) 5.9mb(USGS) 7.5MS(USGS) 7.8MS(BRK) 7.2MS(PAS)

12.69 S 166.00 E 5.2mb(USGS) 6.7MS(USGS) 6.9MS(BRK) 6.4MS(PAS) 5.8mb 7.9MS 8.0MS(BRK) 7.5MS(PAS)

12.52 S 165.92 E

Depth 10 km. At least 56 people k i l l e d , 400 or more injured, and extensive damage ( V I I I ) on Tecceira. At least four people k i l l e d , some injured, and extensive damage on Sao Jorge. Damage a l s o reported on Grac iosa . Rocksl ides and minor damage

Depth 44 km. Fel t ( V I I ) at Malokur i Iskoye, IV at K u r i l s k , and I I I at Yuxhno-K u r i l s k . A lso f e l t ( I V , JMA) at Nemuro and Kushino, Hokkaido and ( I I I , JMA) in the Obihiro-Urakawa area, Hokkaido. 10-cm tsunami reported at Nemuro. Depth 38 km

Depth 140 km.

Depth 5 km. Two people k i l l e d , 100 i n ­jured, and considerable damage in Mexico. Fel t (V) in Yuma County, Ar izona, Imper ia l , and San Diego Count ies, C a l i f o r n i a . Depth 54 km. Fel t (MM V) at Sur igao .

Depth 33 km. Fel t in the Banks and Santa Cruz I s l a n d s . Some land-s i ides reported on surround­ing i s l a n d s .

Depth 33 km. F e l t .

Depth 33 km. Fe l t in the Banks Is lands group and Torres I s l a n d s . Tsunami 26.8 cm (peak- to-peak) at Kona, 6.7 cm (peak-to-peak) at Honolulu, and 8.0 cm (peak-to-peak) at Ap ia , Samoa.

* Based on 'Earthquake Data Reports ' published by the US Geological Survey, and on the SEAN B u l l e t i n of the Smithsonian I n s t i t u t i o n .

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TABLE 5 (cont . )

Or ig in time Date (UTC) Region L a t . Long, Magn itude Remarks

22 July 05 17 10.1 Caspian Sea

22 July 07 06 23.0 Vanuatu

29 July 03 11 56.3 Vanuatu

29 July 14 58 40.8 Nepal

37.19 N 50.20 E 5.4mb(USGS)

20.30 S 169.61 E 6.Imb(USGS) 6.8mb(BRK) 6.7mb(PAS)

13.10 S 166.34 E 5.9mb(USGS) 6.7MS(USGS) 7.2MSCBRK) 6.7MSCPAS)

29.60 N 81.09 E 6.lmb(USGS) 6.5MSCUSGS) 6.5MSCBRK) 6.6MSCPAS)

9 Aug. 05 45 09.5 Honduras

18 Aug. 15 07 52.6

23. Aug. 21 36 51.6

Offshore Ecuador

Kashmir- Indla border region

15.89 N 88.52 W 6.lmb(USGS) 6.4MSCUSGS) 6.7MSCBRK) 6.4MSCPAS)

1.95 S 80.02 W 5.6mb(USGS) 5.6MSCBRK) 6.imb(PAS)

32.91 N 75.63 E 5.2mb(MSGS) 4.9MSCMSGS)

23 Sep. 19 10 22.7 Honshu, Japan 35.95 N 139.63 E 5.4mb(USGS)

24 Sep. 17 54 24.1 Off east coast 35.45 N 139.96E 6.0mb (USGS) 5.9mb(BRK) of Honshu,

Japan

10 Oct . 12 25 23.7 A lger ia

10 Oct . 15 39 09.8 A lger ia

36.14 N 1.41 E 6.3mb(USGS) 7.3MS(USGS) 7•7MS(BRK)

36.21 N 1.63 E 6.0mb(USGS) 6.0MS(USGS)

Depth 62 km. One person k i l l e d , several injured in the Lahi jan-Rasht area , I r a n . Depth 122 km.

Depth 48 km.

Depth 19 km. 150-200 people k i I led, many injured, and extensive damage in western Nepal . At least 13 k i l l e d , 40 injured, and damage in the Pi thoragarh area, I n d i a . Fe l t s t rong ly at Kathmandu, and New Del hi area Depth 22 km. Two people k i l l e d , many i n ­jured in Izabal Prov ince, Guatemala. A l s o damage in northern Honduras. Depth 55 km. E ight people reported k i l l e d , 100 injured, and extensive damage in the Guayaqui I ' a rea . Depth 25 km. 15 people ki11ed, at least 40 injured, and many houses damaged in the Bhaddu area, Kashmir. Fel t in northern India and in the Lahore-Peshawar area, P a k i s t a n . Depth 89 km. One person k i l l e d , f i v e injured. Fel t ( I V , JMA) at Utsunomiya and ( I I I , JMA) in the Maebash i-Chosh i-Aj i ro area. Two people k i l l e d , at least 73 injured and damage ( I V , JMA) in the Tokyo-Tateyama-Utsunamiya area. Depth 10 km. 5000 people k i l l e d , 9000 injured, and over 200 000 homeless; extensive damage in the El Asnam area. Fel t throughout northwestern A lger ia and southeastern Spa i n . Depth 10 km. Addit ional deaths and damage.

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TABLE 5 (cont . )

O r i g i n time Date (UTC) Region L a t . Long. Magnitude Remarks

24 Oct . 14 53 35.3 Central Mex ico

18.23 N 98.27 W 6.4mb(USGS) 6.6mb(BRK) 7.0MS(BRK)

25 Oct . 11 00 05.0 Loyalty I s lands 21.90 S 169.86 E 5.8mb(USGS) 7.2MSCUSGS) 7.1 MS(BRK)

41.16 N 124.34 W 6.2mb(USGS) 8 Nov. 10 27 33.4

reg ion

Off shore Northern C a l i f o r n ia

12. Nov. 06 58 10.5 Peru

19 Nov. 19 00 49.1

23 Nov.

19 Dec.

18 34 53.3

01 16 56.1

Sikkim

Southern I t a l y

I ran

22 Dec. 12 51 17.6 Iran

7.4MS(USGS) 7.0MKBRK)

13.09 S 74.45 W 5.2mb(USGS)

27.37 N 88.75 E 6.0mb(USGS) 6.0MS(USGS)

40.89 N 15.33 E 6.lmb(USGS) 6.8MS(USGS) 7.2MSCBRK) 6.9MS(PAS) 6.7mb(PAS)

34.62 N 50.68 E 5.5mb(USGS) 5.8MS(USGS)

34.35 N 50.40 E 5.2mb(USGS) 5.2MS(USGS)

Depth 74 km. Unconfirmed reports of at least 300 people k i l l e d , many injured, approximately 150 000 homeless and extensive damage in central Mexico, mainly in the Huajuapan de Leon area. Fe l t throughout central and southern Mexico and in Guatemala. Depth 33 km.

Depth 14 km. Five people injured and con­s iderable damage in the Eureka area. Fe l t from San Francisco to Salem, Oregon. Depth 33 km. Four people k i l l e d and 20 injured in the Ayacucho area. Depth 33 km. Four people injured and minor damage in the Gangtok area . Fe l t in Nepal , Bhutan, and eastern I n d i a . Depth 10 km. At least 3100 people k i l l ­ed, about 2000 m i s s i n g , 7760 injured, 170 000 home­l e s s , and extensive damage. Depth 33 km. 26 peopIe k i I Ied, some injured, and damage in the Qom-Saveh area. Fel t at Tehran. Depth 18 km. Three people k i l l e d , 139 injured, and damage in the

Qom area. Fel t at Tehran.

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REFERENCES

ANDERSON, J.A., & WOOD, H.O., 1925 - Description and theory of the torsion seismometer. Bulletin of the Seismological Society of America, 15, 1-72.

BATH, M., 1981 - Earthquake magnitude - recent research and current trends. Earth Science Reviews, 17, 315-398.

DENHAM, D., 1982 - Proceedings of the workshop on Australian Earthquake magnitude scales, BMR, Canberra, 21 May 1982. Bureau of Mineral Resources, Australia, Record 1982/29.

EIBY, G.A., 1966 - The Modified Mercalli scale of earthquake intensity and its use in New Zealand. New Zealand Journal of Geology and Geophysics, 9, 122-129-

GREGSON, P.J., 1982 - Mundaring Geophysical Observatory Annual Report, 1980, Bureau of Mineral Resources, Australia, Record 1982/9.

GUTENBERG, B., 1945 - Amplitudes of P, PP and SS, and magnitudes of shallow earthquakes. Bulletin of the Seismological Society of America, 35, 57-69.

McGREGOR, P.M., & RIPPER, I.D., 1976 - Notes on earthquake magnitude scales. Bureau of Mineral Resources, Australia, Record, 1976/56.

RICHTER, C.F., 1958 - ELEMENTARY SEISMOLOGY. Freeman & Co., San Francisco.

WILLMORE, P.L., 1979 - Manual of Seismological Observatory Practice, World Data Center A for Solid Earth Geophysics. Report SE-20. US Department of Commerce, Boulder, Colorado, USA.

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APPEND1X

M O D I F I E D MERCALL1 (MM) S C A L E OF EARTHQUAKE I N T E N S I T Y

( a f t e r E i b y , 1966)

MM I Not f e l t by h u m a n s , e x c e p t in e s p e c i a l l y f a v o u r a b l e c i r c u m s t a n c e s , b u t b i r d s and a n i m a l s may be d i s t u r b e d . R e p o r t e d m a i n l y f r o m the upper f l o o r s o f b u i l d i n g s more t h a n t e n s t o r e y s h i g h . D i z z i n e s s o r n a u s e a may be e x p e r i e n c e d . B r a n c h e s o f t r e e s , c h a n d e l i e r s , d o o r s , and o t h e r s u s p e n d e d s y s t e m s o f l o n g n a t u r a l p e r i o d may be s e e n t o move s l o w l y . Water i n p o n d s , l a k e s , r e s e r v o i r s , e t c . , may be s e t i n t o s e i c h e o s c i l l a t i o n .

MM I I F e l t by a few p e r s o n s a t r e s t i n d o o r s , e s p e c i a l l y by t h o s e on u p p e r f l o o r s o r o t h e r w i s e f a v o u r a b l y p l a c e d . The l o n g - p e r i o d e f f e c t s l i s t e d under MM I may be more n o t i c e a b l e .

MM I I I F e l t i n d o o r s , b u t n o t i d e n t i f i e d a s an e a r t h q u a k e by e v e r y o n e . V i b r a t i o n s may be I i k e n e d t o t h e p a s s i n g o f I i g h t t r a f f i c . I t may be p o s s i b l e t o e s t i m a t e t h e d u r a t i o n , b u t n o t t h e d i r e c t i o n . H a n g i n g o b j e c t s may s w i n g s l i g h t l y . S t a n d i n g m o t o r c a r s may r o c k s l i g h t l y .

MM IV G e n e r a l l y n o t i c e d i n d o o r s , b u t n o t o u t s i d e . V e r y l i g h t s l e e p e r s may be a w a k e n e d . V i b r a t i o n may be l i k e n e d t o t h e p a s s i n g o f h e a v y t r a f f i c , o r t o t h e j o l t o f a h e a v y o b j e c t f a l l i n g o r s t r i k i n g t h e b u i l d i n g . W a l l s and f rame o f b u i l d i n g a r e h e a r d to c r e a k . D o o r s and w i n d o w s r a t t l e . G l a s s ­ware and c r o c k e r y r a t t l e . L i q u i d s in open v e s s e l s may be s l i g h t l y d i s t u r b e d . S t a n d i n g m o t o r c a r s may r o c k , and t h e s h o c k c a n be f e l t by the i r o c c u p a n t s .

MM V G e n e r a l l y f e l t o u t s i d e , and by a l m o s t e v e r y o n e i n d o o r s . M o s t s l e e p e r s a w a k e n e d . A few p e o p l e f r i g h t e n e d . D i r e c t i o n o f m o t i o n c a n be e s t i m a t e d . S m a l l u n s t a b l e o b j e c t s a r e d i s p l a c e d or u p s e t . Some g l a s s w a r e and c r o c k e r y may be b r o k e n . Some w indows c r a c k e d . A few e a r t h e n w a r e t o i l e t f i x t u r e s c r a c k e d . H a n g i n g p i c t u r e s m o v e . D o o r s and s h u t t e r s s w i n g . P e n d u l u m c l o c k s s t o p , s t a r t , or c h a n g e r a t e .

MM VI F e l t by a l l . P e o p l e and a n i m a l s a l a r m e d . Many r u n o u t s i d e . D i f f i c u l t y e x p e r i e n c e d in w a l k i n g s t e a d i l y . S l i g h t damage t o M a s o n r y D b u i l d i n g s . Some c r a c k s or f a l l s . I s o l a t e d c a s e s o f c h i m n e y d a m a g e . Windows and c r o c k e r y b r o k e n . O b j e c t s f a l l f rom s h e l v e s , and p i c t u r e s from w a l l s . Heavy f u r n i t u r e m o v e d . U n s t a b l e f u r n i t u r e o v e r t u r n e d . S m a l l c h u r c h and s c h o o l b e l l s r i n g . T r e e s and b u s h e s s h a k e , o r a r e h e a r d t o r u s t l e . M a t e r i a l may be d i s l o d g e d f rom e x i s t i n g s l i p s , t a l u s s l o p e s , o r s l i d e s .

MM V I I G e n e r a l a l a r m . D i f f i c u l t y e x p e r i e n c e d in s t a n d i n g . N o t i c e d by d r i v e r s o f m o t o r c a r s . T r e e s and b u s h e s , s t r o n g I y s h a k e n . L a r g e b e l l s r i n g . M a s o n r y D c r a c k e d and d a m a g e d . A few i n s t a n c e s o f damage t o M a s o n r y C L o o s e b r i c k w o r k and t i l e s d i s l o d g e d . U n b r a c e d p a r a p e t s and a r c h i t e c t u r a l o r n a m e n t s may f a l l . S t o n e w a l l s c r a c k e d . Weak c h i m n e y s b r o k e n , u s u a l l y a t t h e r o o f - l i n e . D o m e s t i c wa te r t a n k s b u r s t . C o n c r e t e i r r i g a t i o n d i t c h e s d a m a g e d . Waves s e e n on p o n d s and l a k e s . Water made t u r b i d by s t i r r e d - u p m u d . S m a l l s l i p s , and c a v i n g - i n o f s a n d and g r a v e l b a n k s .

- 25 -

C a t e g o r i e s o f n o n - w o o d e n c o n s t r u c t i o n , e t c .

M a s o n r y A S t r u c t u r e s d e s i g n e d to r e s i s t l a t e r a l f o r c e s o f a b o u t 0 . 1 g , s u c h a s t h o s e s a t i s f y i n g t h e New Z e a l a n d Model B u i l d i n g B y l a w , 1 9 5 5 . T y p i c a l b u i l d i n g s o f t h i s k i n d a r e wel l r e i n f o r c e d by means o f s t e e l or f e r r o ­c o n c r e t e b a n d s , or a r e w h o l l y o f f e r r o - c o n c r e t e c o n s t r u c t i o n . A M m o r t a r i s o f g o o d qual I t y and t h e d e s i g n and w o r k m a n s h i p i s g o o d . Few b u i l d i n g s e r e c t e d p r i o r t o 1935 can be r e g a r d e d a s M a s o n r y A .

M a s o n r y B R e i n f o r c e d b u i l d i n g s o f g o o d w o r k m a n s h i p and w i t h some m o r t a r , b u t n o t d e s i g n e d , in d e t a i l to r e s i s t l a t e r a l f o r c e s .

M a s o n r y C B u i l d i n g s o f o r d i n a r y w o r k m a n s h i p , w i t h m o r t a r o f a v e r a g e q u a l i t y . No e x t r e m e w e a k n e s s , s u c h a s i n a d e q u a t e b o n d i n g o f t h e c o r n e r s , b u t n e i t h e r d e s i g n e d nor r e i n f o r c e d t o r e s i s t l a t e r a l f o r c e s .

MM V I M A l a r m may a p p r o a c h p a n i c . S t e e r i n g o f m o t o r c a r s a f f e c t e d . M a s o n r y C d a m a g e d , w i t h p a r t i a l c o l l a p s e . M a s o n r y B damaged in some c a s e s . M a s o n r y A u n d a m a g e d . C h i m n e y s , f a c t o r y s t a c k s , m o n u m e n t s , t o w e r s , and e l e v a t e d t a n k s t w i s t e d or b r o u g h t d o w n . P a n e l w a l l s t h r o w n o u t o f f r a m e s t r u c t u r e s . Some b r i c k v e n e e r s d a m a g e d . D e c a y e d wooden p i l e s b r o k e n . Frame h o u s e s n o t s e c u r e d t o t h e f o u n d a t i o n may m o v e . C r a c k s a p p e a r on s t e e p s l o p e s and in wet g r o u n d . L a n d s l i p s in r o a d s i d e c u t t i n g s and u n s u p p o r t e d e x c a v a t i o n s . Some t r e e b r a n c h e s may be b r o k e n o f f .

MM IX G e n e r a l p a n i c . M a s o n r y D d e s t r o y e d . M a s o n r y C h e a v i l y d a m a g e d , s o m e t i m e s c o l l a p s i n g c o m p l e t e l y . M a s o n r y B s e r i o u s l y d a m a g e d . F rame s t r u c t u r e s r a c k e d and d i s t o r t e d . Damage t o f o u n d a t i o n s g e n e r a l . Frame h o u s e s n o t s e c u r e d t o t h e f o u n d a t i o n s s h i f t e d o f f . B r i c k v e n e e r s f a l l and e x p o s e f r a m e s . C r a c k i n g o f t h e g r o u n d c o n s p i c u o u s . M i n o r damage t o p a t h s and r o a d w a y s . Sand and mud e j e c t e d in a l l u v i a t e d a r e a s , w i t h t h e f o r m a t i o n o f e a r t h q u a k e f o u n t a i n s and s a n d c r a t e r s . U n d e r g r o u n d p i p e s b r o k e n . S e r i o u s damage t o r e s e r v o i r s .

MM X M o s t m a s o n r y s t r u c t u r e s d e s t r o y e d , t o g e t h e r w i t h t h e i r f o u n d a t i o n s . Some w e l l - b u i l t wooden b u i l d i n g s and b r i d g e s s e r i o u s l y d a m a g e d . D a m s , d y k e s , and embankments s e r i o u s l y d a m a g e d . R a i l w a y l i n e s s l i g h t l y b e n t . Cement and a s p h a l t r o a d s and p a v e m e n t s b a d l y c r a c k e d or t h r o w n i n t o w a v e s . L a r g e l a n d s l I d e s on r i v e r b a n k s and s t e e p c o a s t s . Sand and mud on b e a c h e s and f l a t l a n d moved h o r i z o n t a l l y . L a r g e and s p e c t a c u l a r s a n d and mud f o u n t a i n s . Water f rom r i v e r s , l a k e s , and c a n a l s t h r o w n up on t h e ban ks *

MM X I Wooden f r a m e s t r u c t u r e s d e s t r o y e d . G r e a t d a m a g e t o r a i l w a y l i n e s . G r e a t damage t o u n d e r g r o u n d p i p e s .

MM X I I Damage v i r t u a l l y t o t a l . P r a c t i c a l l y a l l w o r k s o f c o n s t r u c t i o n d e s t r o y e d or g r e a t l y d a m a g e d . L a r g e r o c k m a s s e s d i s p l a c e d . L i n e s o f s l i g h t and l e v e l d i s t o r t e d . V i s i b l e w a v e - m o t i o n o f t h e g r o u n d s u r f a c e r e p o r t e d . O b j e c t s t h r o w n u p w a r d s i n t o t h e a i r .

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M a s o n r y D

W f ndows

Ch I m n e y s

B u i l d i n g w i t h low s t a n d a r d s o f w o r k m a n s h i p , p o o r m o r t a r , o r c o n s t r u c t e d o f weak m a t e r i a l s l i k e mud b r i c k and rammed e a r t h . Weak nor i z o n t a M y .

Window b r e a k a g e d e p e n d s g r e a t l y upon t h e n a t u r e o f t h e f r a m e and i t s o r i e n t a t i o n w i t h r e s p e c t t o t h e e a r t h q u a k e s o u r c e . Windows c r a c k e d a t MM V a r e u s u a l l y e i t h e r l a r g e d i s p l a y w i n d o w s , o r w indows t i g h t l y f i t t e d t o m e t a l f r a m e s .

The ' w e a k c h i m n e y s ' l i s t e d under MM V I I a r e u n r e i n f o r c e d d o m e s t i c c h i m n e y s o f b r i c k , c o n c r e t e b l o c k , o r p o u r e d c o n c r e t e .

W a t e r t a n k s The ' d o m e s t i c w a t e r t a n k s 1 l i s t e d u n d e r MM V I I a r e o f t h e c y l i n d r i c a l c o r r u g a t e d - I r o n t y p e common I n New Z e a l a n d r u r a l a r e a s . I f t h e s e a r e o n l y p a r t l y f u l l , movement o f t h e wa te r may b u r s t s o l d e r e d and r i v e t e d s e a m s . H o t - w a t e r c y l i n d e r s c o n s t r a i n e d o n l y by s u p p l y and del i v e r y p i p e s may move s u f f i c i e n t l y t o b r e a k p i p e s a t a b o u t t h e same I n t e n s i t y •

u. L/ennam a r. j . o r e g s o n Austra l ian s e i s m o i o g i c a i r e p o n IMHU