EARTHQUAKE UNIT
Margaret D. Wiggins-Grandison BSc UWI, MS Atl. U,
PhD U. Bergen  – Research Fellow/Seismologist
WORK OF THE DEPARTMENT
Caribbean Tsunami Warning System
Arising from the devastating BoxingDay 2004 Indian Ocean tsunami, the
US Government mandated the US
Geological Survey and the National
Oceanic and Atmospheric Administra- tion 
to establish a Tsunami Warning System
(TWS) in the Caribbean.  To this end the
Caribbean is to receive nine Very Broad-
Band six-component seis- mograph
stations of the highest quality and five Deep 
Ocean Assessment and Reporting of
Tsunamis (DART) II buoys each having
real-time satellite communication links with the USGS National
Earthquake Information Centre or NOAA. In December two members
of the United States Geological Survey (USGS) team visited Jamaica to
discuss with the GOJ the establishment of one of the seismograph stations 
in Jamaica. The project would be financed entirely by the US Government
including training of locals in maintaining the station and delivering the
data to the EQU, who would operate as the first local contact.  Dr.
Wiggins-Grandison took the visitors to three sites that satisfied their
requirements, NEJ, BBJ and CVJ that were also existing stations of the
Jamaica Seismograph Network.  CVJ was selected with BBJ as the runner-
up.  An MOU outlining the terms of the bilateral cooperation was
presented to the GOJ. On Earthquake Awareness Day in January 2006 the 
then Ministry of Land and Environment held a press conference in which
an intention to sign the MOU was signed by her Excellency US
Ambassador Johnson and the Honourable Minister Dean Peart.  At the
time of writing the MOU is still a work in progress.
Spectral Seismic Hazard Maps for Jamaica
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In March two spectral seismic hazard maps representing long and short
period ground accelerations with a two percent probability of exceedence
were handed over to the National Building Code Committee.  The maps
were the result of an extensive study by M. Wiggins-Grandison. They
conform to the guidelines of the International Building Code which is
being promulgated into law for Jamaica.  A brochure on the maps has also
been prepared.  A more detailed paper for publication will follow.
Microzonation of Kingston
M. Wiggins-Grandison attended a second workshop of the UNESCO-
IUGS-IGCP Project 487, “Microzonation of Latin American Cities”. This 
time it was held at the Engineering Department, University of San Jose in
Costa Rica, October 18-26, 2005
Other
As usual staff were involved in the ODPEM’s Earthquake Awareness
Week and Disaster Preparedness Month activities, UWI’s Research Day
and Jamaica National Heritage Trust’s commemoration of the Port Royal
earthquake.  Over 550 students and teachers visited the Unit and the Unit
participated in Savanna-la-Mar Primary’s Disaster Preparedness
exhibitions in June.
About eighty-three (83) trips were made to maintain the three networks of
recording instruments.  
Jamaica Seismograph Network (JSN)
Finally, the last two stations damaged from Hurricane Ivan were dealt
with.  The Jamaica Constabulary erected a new antenna tower at CMJ in
August-September 2005 enabling that station to be rebuilt.  The Harbour
Master’s Department re-roofed the building at PCJ during May to July
2006 enabling both the seismograph and the continuous Global
Positioning System (GPS) receiver to be reinstated in a dry, secure
environment.  Since September 2004 those equipment had been operating 
under a tarpaulin which contributed to the downtime of PCJ as well as
YHJ which is relayed through PCJ.
For northern and western stations much of the down time is attributable
to lightning damage at Cooper’s Hill which is the relay point for these
stations, this despite the use of lightning protection cells. This year,
Cooper’s Hill was placed on solar energy which has decreased the impact
of the damage.  A number of options about how to eliminate/minimize
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this problem were examined including the possibility of shifting the relay
point to Stony Hill, where there has been historically lower incidence of
lightning strikes.  However, a higher tower will be required there to
achieve line-of-sight with the outlying stations.
Figure 1. Station Performance in terms of percentage of earthquakes recorded. 
Most stations rebounded since Hurricane Ivan. Exceptions are: (1) MCJ
that experienced a period of noisy signals caused by weather-worn cables
and weak batteries, which had to be replaced; (2) NEJ that continued to
operate in an electronically noisy environment from which it must be
removed; (3) YHJ that was inaccessible for much of 2005 due to unsafe
road conditions brought on by the excessive rainfall. Stations exhibiting
significant gains over the period include BBJ, CMJ, GWJ, HOJ and MBJ.
[Background is the undeveloped site of NEJ at Mount Airy,
Westmoreland.]
Figure 2.  JSN Performance.
For 2005-6, the number of earthquakes recorded by 9-12 stations
increased three-fold when compared to the previous two years. 
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Concrete plans were drafted to build adequate infrastructure and use solar
energy at stations giving priority to those that need it most, NEJ, YHJ and
BBJ.  Estimates were included in the budget for 2006-7. A significant
amount of investigation concerning the choice of equipment for
upgrading stations from analogue to digital has taken place and will
continue into next year. Investigations also focussed on a new
communication system for staff and digital instruments alike using the flat
rate Oceanic Digital/MiPhone CDMA wireless service.
In March two new personal computers for data acquisition were received
and a new data acquisition system employing an economical 32-channel
SARA digitizer and SEISLOG freeware from University of Bergen was
installed and tested.  The Central Recording Station (CRS) was
rehabilitated and tidied by replacing and ducting weather-worn antenna
cables and internal wiring.  In addition renovation and upgrading to the
solar power system at the CRS began with the aim of improving its
efficiency. 
Following a series of major repairs, the Unit’s vehicle, a 1998 Subaru
Forrester broke down on July 11 and was declared irreparable.  Station
maintenance therefore was hampered until the end of the month when the 
GOJ loaned the Unit a vehicle.  It is anticipated that enough money to
purchase a new 4-wheel drive vehicle will be provided in the 2006-7
budget.
The Jamaica Strong Motion Network
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This year Kinemetrics Inc. repaired and returned to us FOC an ETNA
digital accelerometer that had been damaged since two years ago.
Successive budgets of the EQU could not support the repair cost of
US$3,600.00.  In August 2005 yet another Etna was damaged and repairs
have been assessed at US$2,000.00. Engineers from Oceanic Digital
worked with EQU engineering staff testing wireless CDMA
communications with the ETNA digital instrument.  Aspects of the tests
were positive and supportive of continued testing.
GPS network
A first manuscript that integrated the findings of the initial five years of
GPS measurements in Jamaica with Jamaican seismicity was drafted and
submitted for publication by C. DeMets (U. Wisconsin) and M. Wiggins-
Grandison.
In April the two Ashtech GPS receivers and data-bridges were redeployed
at Pike and at Portland Cottage lighthouse.  During May to July six new
sites were selected for GPS measurements: Manchioneal, Kempshot,
Munro College, Braeton and Manatee Bay both in the Hellshire Hills, and
Big Goat Island.  A short talk on GPS and its use in Jamaica was well
received by Munro College fourth form geography students and teacher,
many of whom had not heard the term before.
Earthquakes Recorded
105 local earthquakes were recorded with magnitudes between 1.1 and 4.3. 
The largest was offshore Black River. Six minor/light earthquakes were
felt, none causing any damage. Another thirty-nine events (39) were
attributed to man-made explosions.
Seismicity for 2005-6 was dominated by earthquakes occurring in the Blue
Mountains, followed by the central Rio Minho-Crawle River fault zone,
the Wagwater Trough South, Wagwater Trough North, Buff Bay and
Montpelier-Newmarket Belt, in that order, all  traditional zones of higher
activity.
Forty-five (45) earthquakes were located in the near-Jamaica region.  Most
were situated in the Oriente Fracture Zone/Cayman Trough that lies
between Jamaica and south-eastern Cuba. In addition 45 regional and 32
distant earthquakes were recorded bringing the total number of events this 
year to 267.
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PAPERS PRESENTED
• M.D. Wiggins-Grandison, “Towards IBC Seismic Hazard Maps
for Jamaica”, 50th Anniversary of the Geological Society of
Jamaica Conference, Mona Visitor’s Lodge, December 1 - 4, 2005 
(oral)
• M.D. Wiggins-Grandison, “Jamaican Seismology with reference
to other islands in the Greater Antilles”, Caribbean Division of
Structural Engineers 2-day conference on Earthquake
Engineering, Mount Irvine Bay Hotel, Tobago, December 5 - 6,
2005 (oral, invited)
• M. D. Wiggins-Grandison, “The Preparation of IBC Seismic
Hazard Maps for Jamaica”, Jamaica Institution of Engineers &
Institution of Structural Engineers – Caribbean Division Joint
Technical Session: Selection of Seismic Design Values for Use in
Jamaica, University of Technology, June 8, 2006 (oral).
INCOME GENERATION
The EQU delivered three small consultations which earned just over
$40,000.00. Work progressed satisfactorily on a seismic risk assessment
for NEM Insurance Company Ltd. The project valued at over $2 million,
involved two weeks of site response measurements in Kingston and
employed one Scientific Officer for one year.
PUBLIC SERVICE
– Member, National Data Centre, Comprehensive (Nuclear)
Test-Ban Treaty Organization (CTBTO)
– Member, Federation of Digital Seismograph Networks (FDSN)
– Member, International Seismological Centre (ISC)
– Member, Middle America Digital Seismograph Con- sortium
(MIDAS)
– Member, National Committee on Science and Technology
(NCST)
– Member, National Disaster Committee (NDC)
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– Member, US Caribbean Seismic Station Network (USCaribNet)
– Member, West Indies Group of University Teachers Executive
(WIGUT)
– Member, Senior Common Room (SCR) Management
Committee 
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