Caribbean Disaster Mitigation Project
Implemented by the Organization of American States
Unit of Sustainable Development and Environment
for the USAID Office of Foreign Disaster Assistance and the Caribbean Regional Program

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Final Report: Kingston Metropolitan Area Seismic Hazard Assessment
Appendix 1: Jamaican Earthquake Data

Download a Microsoft Excel File of Jamaican Earthquake Data.


Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5
Bibliography Appendix 1 Appendix 2 Appendix 3

Figure A1.0 Maxwell Hall's 1922 map of earthquake 'epicenters' in Jamaica. The lettered circles mark persistent concentrations of seismic activity, as determined by Hall, during the period 1880 to 1919. The circle marked 'H' is Hall's epicenter for the 1907 Kingston earthquake.


A 1.0 Introduction

This Appendix contains a description of the 100 year instrumental earthquake catalog that was assembled for this assessment, a brief history of the Jamaican seismograph network, in formation on a magnitude calibration, and a description of the Modified Mercalli and Rossi-Forel intensity scales.

A1.1 Jamaican Earthquake Catalog

The Jamaican Earthquake catalog (Table A1.1) lists locations and magnitudes for instrumentally recorded earthquakes during the time period 1899 to 1996 within the area between 14o - 22o N and 72o - 82o W. These events are also shown in map format in Figure A1.1.

The completeness of the catalog varies considerably during the 20th Century. At the beginning of the century, only the largest events were reported - often with large uncertainties ( 1o) in location and magnitude. The 14 June 1899 earthquake for example, is located at 18o N, 77o W - directly in the center of Spanish Town (see Figure A1.1). While this event was felt through out the island, the highest reported intensity, MMI V, contradicts the reported magnitude, 7.8 and suggests a location elsewhere.

Seismic instrumentation was installed in Jamaica following the 1907 earthquake, however, these were non-calibrated, non-standardized instruments with poor time keeping (Shepherd and Aspinall, 1980).

A review of earthquakes in the International Seismological Summary (ISS) from 1913 to 1939 by Rutten and Van Raadshooven (1940) indicated a number of earthquakes with large intensities not registered by 'local' seismographs located in Tacubaya (1500 km), New Orleans (2000 km), Washington (2300 km), and Saint Louis (2700 km). These events are not listed in ISS catalogs for this period, and are not included in Table A1.1. These events include: August 19, 1914 [Rossi Forell (RF) Intensity VII]; October 14, 1914 [RF VII-VIII]; December 24, 1914 [RF VII]; November 25, 1921 [RF VII?]; and July 14, 1936 and are discussed further in Section 2 of the Final Report.

The overall accuracy of locations and the reporting of smaller earthquakes in this region improved with the advent of computerized earthquake location programs and the installation of the World Wide Standardized Seismograph Network in the 1960's. Installation of a local seismograph network on Jamaica in the 1960's and the steady improvement of that network throughout the last 30 years have enabled the recording of events too small to be detected by global networks.

The catalog in Table A1.1 combines earthquake locations and magnitudes from a number of sources covering different time periods. Our criteria for selection, when multiple earthquake locations were available, is summarized in the list below which ranks sources from highest to lowest priority for selection.

Earthquake magnitudes reported in the catalog are predominately mb or body wave magnitudes. While the lower cut off threshold is nominally M > 3.4, we have also included many events that do not have magnitude determinations. These additional events can be used to delineate active tectonic features in the region. Selection priorities range from (highest to lowest):

Magnitude determinations for specific events include

An electronic version of the Jamaican Earthquake Catalog is available as an Excel spreadsheet file in http://www.oas.org/en/cdmp/hazmap/kma.htm

Figure A1.1 One hundred years of seismicity near Jamaica. Map is developed from the earthquake catalog produced in this study (see Appendix 1), and is overlain upon the relief map shown in Figure 3.3. See the caption to Figure 3.3 for an explanation of the relief data. The size of the circles is proportional to magnitude and the solid black circles represent events with no magnitude reported. Earthquake locations prior to 1950 are less certain than more recent events and are shown as gray shaded circles. Large events have the year of occurrence listed.

A1.2 Jamaican Seismic Network

Since the late 1960's, the University of the West Indies has operated the Jamaican Seismograph Network (JSN). The JSN started with one station and had as many as nine stations operating during the first 25 years. As seen in Figure A1.2, the performance of the JSN has varied considerably during the last 30 years. Prior to 1989, Mark Products vertical 1 Hertz seismometers were used along with generic amplifiers and discriminators. The Network was telemetered to a Central Recording Site at the UWI Mona Campus. Until 1989, only analog recording was available using a pen and ink drum recorder and a 24-channel thermionics FM tape recorder. Network timing was via WWV radio broadcast.

Figure A1.2 Numbers earthquake locations computed by the Jamaican Seismograph Network and active seismographs during the period 1973 to 1998.

In 1990, the Central Recording Site adopted the Soufriere System (SRU, 1984, 1977) for the digital recording and playback of earthquake data. A Kinemetrics 468-DC 'GOES' (Geostationary Operational Environmental Satellite) synchronized clock provided network timing to 0.001-sec accuracy. The Soufriere System was in operation until July 1997.

Figure A1.3 Microearthquakes located in the vicinity of Jamaica by the local seismic network.

Incoming seismic signals were digitized at 100 samples per second. Coda length duration magnitudes were computed using the formula

M = 2.073 log (D) + 0.0018 (R) - 0.705,

where D is the coda duration in seconds and R is the hypocentral distance in kilometers. Shepherd and Aspinall (1983) developed this relationship from an analysis of Lesser Antilles earthquakes and believed it to be equivalent to USGS mb magnitudes to within 0.2 magnitude units. During this time, however, the JSN was uncalibrated and used low gain (56 dB) amplifiers with noisy and intermittent stations. Based on this formula, the JSN assigned a magnitude of 5.4 for the 1993 Woodford Jamaica earthquake. The corresponding ISC magnitude was 5.5. Figure A1.3 shows microearthquakes located in the vicinity of Jamaica during the period 1990 to 1996 (Wiggins-Grandison, 1997).

In early 1997, a program to improve the JSN was started. Existing equipment was replaced with Teledyne-Brown/Geotech instruments and either new or refurbished Mark Products sensors. UHF band transmitters and receivers were also installed. The new JSN currently consists of nine calibrated high-gain short-period seismograph stations (two of which are three-component stations, see Figure A1.4) and five low-gain seismometers. The network also contains three digital accelerographs, though no data from strong earthquakes have been recorded to date. Data acquisition and processing is based on software developed at the Seismological Division of the Geophysical Institute of Israel. All stations are calibrated and the response functions are known and documented. Network timing is provided using a Trimble GPS receiver.

Figure A1.4 Stony Hill seismograph station (STH). Photo shows instrument pier, three L4 seismometers and a SSA-2 strong motion accelerometer.

A1.3 Network Magnitude Calibration

Magnitudes used for calibration in this study date from 1978 to 1996 (the majority being from the 1990's) and were solved using JSN data. The goal was to identify larger events that were recorded both teleseismically and by the JSN and compare coda duration magnitudes with reported mb values. Low rates of moderate earthquake activity and the intermittent status of the JSN limited the number of events available for comparison during this time. There are about 68 teleseismically recorded events in the Jamaica region between 1970 and 1989, as listed in the Pan American Institute of Geography and History (PAIGH) catalog (Shepherd et al., 1994). One third of these events occurred prior to 1977, unfortunately, no coda magnitudes are available for that time period. Between 1980 and 1985 there were 27 events, many of which have either coda magnitudes or mb magnitudes, but not both. Many events occurring between 1986 and 1989 were not recorded due to network problems, see Figure A1.2.

Figure A1.5 Plot of mb/Mcoda for selected JSN events

Table A1.2 lists 18 earthquakes for which coda duration and mb magnitudes are available. Except for those marked GWJ, the coda magnitudes were determined from the station Stony Hill (STH) which is the most consistently used station over the duration of the catalog, 1978 to 1996. These data are plotted in Figure A1.5.

Table A1.2 Earthquake magnitude calibration events

Event ID

Coda (sec)

Distance (km)

Mcoda

mb

Notes

9005222035

254

207

4.7

5.1

STH

9005300239

638

79

5.3

5.2

STH

9009040803

463

174

5.1

5.2

STH

9010301234

222

217

4.6

4.6

STH

9010310331

285

201

4.8

4.8

STH

9205251655

1354

214

6.2

6.3

STH

9207241858

199

145

4.3

4.5

STH

9211062220

180

157

4.3

3.7

STH

9211070317

245

179

4.6

4.7

STH

9301131711

713

3

5.2

5.5

GWJ

9402152258

158

17

3.9

3.9

GWJ

9406040725

600

219

5.5

4.5

STH

9506032142

162

7

3.9

3.8

GWJ

9509080708

257

128

4.5

4.3

STH

9512241713

261

232

4.7

3.8

STH

9607021409

227

139

4.4

4.4

STH

9610091926

184

58

4.1

4.7

STH

 

250

207

4.6

5.0

 

A1.4 Earthquake Intensity Scales

Rossi-Forel Scale (1883)

  1. Microseismic shock. Felt by an experienced observer.
  2. Extremely feeble shock. Felt by a small number of persons at rest.
  3. Very feeble shock. Felt by several persons at rest. Strong enough for direction or duration to be appreciable.
  4. Feeble shock. Felt by persons in motion; disturbance of movable objects, doors, windows, crackling of ceilings.
  5. Shock of moderate intensity. Felt generally by everyone; disturbance of furniture, beds, etc. ringing of some bells.
  6. Fairly strong shock. General awakening of those asleep; general ringing of bells; oscillation of chandeliers; stopping of clocks; visible agitation of trees and shrubs; some startled persons leaving their dwellings.
  7. Strong shock. Overthrow of movable objects; fall of plaster; ringing of church bells; general panic, without damage to buildings.
  8. Very strong shock. Fall of chimneys; cracks in the walls of buildings.
  9. Extremely strong shock. Partial or total destruction of some buildings.
  10. Shock of extreme intensity. Great disaster; ruins; disturbance of the strata, fissures in the ground, rocks falls from mountains.

Modified Mercalli Scale (1931, 1956)

  1. Not felt.
  2. Felt by persons at rest, on upper floors, or favorably placed.
  3. Felt indoors. Hanging objects swing. Vibration like passing of light trucks. Duration estimated. May not be recognized as an earthquake.
  4. Hanging objects swing. Vibration like the passing of heavy trucks; or sensation of a jolt like a heavy ball striking the walls. Standing motor cars rock. Windows, dishes, doors rattle. Glasses clink. Crockery clashes. In the upper ranges of IV wooden walls and frames creak.
  5. Felt outdoors; direction estimated. Sleepers wakened. Liquids disturbed, some spilled. Small unstable objects displaced or upset. Doors swing, close, open. Shutters, pictures move. Pendulum clocks start, stop, change rate.
  6. Felt by all. Many frightened and run outdoors. Persons walk unsteadily. Windows, dishes, glassware broken. Knickknacks, books, etc. off shelves. Pictures off walls. Furniture moved or overturned. Weak plaster and masonry D cracked. Small bells ring (church, school). Trees, bushes shaken visibly, or heard to rustle.
  7. Difficult to stand. Noticed by drivers of motor cars. Hanging objects quiver. Furniture broken. Damage to masonry D, including cracks. Weak chimneys broken at roof line. Fall of plaster, loose bricks, stones, tiles, cornices, unbraced parapets and architectural ornaments. Some cracks in masonry C. Waves on ponds; water turbid with mud. Small slides and caving in along sand and gravel banks. Large bells ring. Concrete irrigation ditches damaged.
  8. Steering of motorcars affected. Damage to masonry C; partial collapse. Some damage to masonry B; none to masonry A. Fall of stucco and some masonry walls. Twisting, fall of chimneys, factory stacks, monuments, towers, and elevated tanks. Frame houses moved on foundations if not bolted down; loose panel walls thrown out. Decayed piling broken off.. Branches broken from trees. Changes in flow or temperature of springs and wells. Cracks in wet ground and on steep slopes.
  9. General panic. Masonry D destroyed; masonry C heavily damaged some times with complete collapse; masonry B seriously damaged, general damage to foundations. Fame structures, if not bolted, shifted off foundations. Frames racked. Serious damage to reservoirs. Underground pipes broken.
  10. Conspicuous cracks in ground. In alluviated areas, sand and mud ejected, earthquake fountains, sand craters.
  11. Most masonry and frame structures destroyed with their foundations. Some well built wooden structures and bridges destroyed. Serious damage to dams, dikes, rivers, lakes, etc. Sand and mud shifted horizontally on beaches and flat land. Rails bent slightly.
  12. Rails bent greatly. Underground pipelines completely out of service.
  13. Damage nearly total. Large rock masses displaced. Lines of sight and level distorted. Objects thrown into the air.

Comparison of Modified Mercalli and Rossi-Forel scales

MM

I

II

III

IV

V

VI

VII

VIII

IX

X-XII

RF

I

I-II

III

IV-V

V-VI

VI-VII

VIII-

VIII+ to IX-

IX+

X

Definition of masonry types.

Masonry A- Good workmanship, mortar and design; reinforced, especially laterally, and bound together by using steel, concrete, etc.; designed to resist lateral forces.

Masonry B- Good workmanship and mortar; reinforced, but not designed to resist lateral forces

Masonry C- Ordinary workmanship and mortar; no extreme weaknesses like failing to tie in at corners; but neither reinforced nor designed against horizontal forces.

Masonry D- Weak materials, such as adobe; poor mortar; low standards of workmanship; weak horizontally.

Download a Microsoft Excel File of Jamaican Earthquake Data.


Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5
Bibliography Appendix 1 Appendix 2 Appendix 3

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Page Last Updated: 20 April 2001