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THE UNIT
Scientific Staff


Joan L. Latchman
B.Sc., Upper Second Class Hons. (1980); M.Phil (1998), Ph.D. (2008), UWI
Seismologist
j_latchman@uwiseismic.com
Bio
Joan Latchman is a Trinidadian by birth and joined the Unit in 1972 as a seismology technician. From 1977-1980, a flexi-time arrangement allowed her to work full-time and pursue a full-time Natural Sciences degree programme. She graduated in 1980 with a B.Sc. in Mathematics and Computer Science (Upper Second Class Hons.). An earthquake sequence near Tobago in 1982, for which the relevant authorities were put on alert, started her interest in Tobago seismicity. In 1988, from an international cadre of seismologists, she was selected to join the team of seismologists at the International Seismological Centre in the United Kingdom, for two years, analysing global seismicity. In 1998, she completed an M.Phil. degree, which examined “The Seismic Potential of the S.W. Tobago Fault System. In 1999, she was appointed to the academic staff at the Unit and in 2001 began work on a Ph.D. looking at “Tobago and Earthquakes”.

Responsibilities
Administration, Seismology
 

 Routine Duties:
i. Oversee seismic data collection from over 50 stations in a network distributed throughout the Eastern Caribbean from Trinidad in the south to St. Kitts in the north.
ii. Supervise three (3) technicians, and one (1) senior technician in the processing and interpretation of the collected data.
iii. Prepare earthquake reports for insurance companies and a variety of consultants.
iv. Respond to unusual and/or elevated seismic activity. This may involve field visits/work, communicating with government representatives, the general public and the mass media. Preparation of relevant reports.
v. Participate in the public education outreach programme of the Centre. This programme seeks to increase public awareness and understanding of the geological hazards to which the Eastern Caribbean is vulnerable and includes giving public lectures, locally and regionally, with multi-media support.
vi. Schedule the preservation, in bound volumes, of the Unit’s journal collection.
vii. Publication of Quarterly Bulletin of the Seismic Research Centre.
 

Research Interests
Joan’s primary research interest involves earthquake forecasting from analysis of changing b-values – she is a member of a team with successful forecasts of near Tobago strong earthquakes - North American-South American plate boundary identification using seismicity (stress waves and plate boundaries); and the impact of strong earthquakes on groundwater; spectra of volcanic earthquakes in diagnosing the status of a volcano.

PhD Research Project

Tobago and Earthquakes: This is a PhD project registered with The University of the West Indies. Three (3) themes are under investigation:

  1. Forecasting of the strongest 1997 earthquake near Tobago using b-value analysis and other indicators– this theme reports on the b-value analysis conducted during the activity of 1997, which led to the projection that a stronger earthquake was imminent; examine the data for other short-term indicators of stronger activity.
  2. Projected seismicity near Tobago based on past seismicity near and off to the east of Tobago – this theme examines the entire database of significant earthquakes near, and in the far-field off the east of Tobago, as far as the Vema Fracture Transform, with a view to improving the understanding of the tectonics at work in the generation of earthquakes near Tobago. The possibility of faults being pushed closer to failure by remote earthquakes is becoming of more interest in the seismological community, and this particular chapter is currently being tailored for journal submission at an early date.
  3. Hydrological effects of the April 22, 1997 Tobago earthquake – this theme documents, and analyses the groundwater impact of the strongest shock of the 1997 series, by collecting information from government agencies and property owners. A possible model consistent with the observations is used to determine the change in the size of crack apertures, which gave rise to the large volume of observed groundwater discharge.

CURRENT RESEARCH
 
   1.  Forecasting of the strongest 1997 earthquake near Tobago using b-value analysis, and other indicators – this theme from the Ph.D. research reported on the b-value analysis conducted during the activity of 1997, which led to the projection that a stronger earthquake was imminent; examine the data for other short-term indicators of stronger activity and continues to be used in testing in earthquake forecasting.

   2.  Projected seismicity near Tobago based on past seismicity near, and in the far-field off the east of Tobago – this Ph.D. theme examined the entire database of significant earthquakes near, and in the far-field off the east of Tobago, as far as the Vema Fracture Transform, with a view to improving the understanding the tectonics at work in the generation of earthquakes near Tobago. The possibility of faults being pushed closer to failure by remote earthquakes is becoming of more interest in the seismological community. The association continues to be monitored to assess its utility in forecasting near Tobago earthquakes.

   3.  Hydrological effects of the 1997/04/22 Tobago earthquake – this Ph.D. theme documented, and analysed the groundwater impact of the strongest shock of the 1997 series, by collecting information from government agencies and property owners. A possible model consistent with the observations is used to determine the change in the size of crack apertures, which gave rise to the large volume of observed groundwater discharge. The observation prompted research project 4.

   4.  Radon monitoring in south-west Tobago as a possible seismic forecasting tool.

   5.  Partition Eastern Caribbean into zones for the purpose of analysing piece-wise gradients of the Gutenberg-Richter Law, with a view to recognising the imminence of significant seismic activity. This study also has made accessible previously unavailable ready statistics of earthquake activity associated with the islands of the Eastern Caribbean.

   6.  Apply the piece-wise b-value technique to a global dataset. The study suggested that an earthquake of magnitude greater than 8.5 was possibly imminent. It was for that reason the paper was submitted, with a measure of urgency, to Geophysical Journal International on 2004/12/01. The technique, which was successfully applied to the 1982, and 1997 earthquake sequences, was developed here at the Unit.

   7.  Apply the piece-wise b-value technique to San Andreas Fault activity. Paper being revised for re-submission to Tectonophysics.
   8.  Apply the piece-wise b-value technique to the Sumatran area of the recent great earthquakes.
 
   9.  Possible correlation between Eastern Caribbean volcanic episodes, and remote stimulation. Due
 for oral presentation at the conference marking the 10th anniversary of the eruption of the Soufrière Hills, Montserrat,


STUDENT SUPERVISION


Nirmala Singh (Undergraduate-final year Physics project) b-values of a dataset of Eastern Caribbean earthquakes (Physics Dept., UWI)
 
Jenalee Samaroo – C.O.R.E Internship Programme 17th May – 9th July, 2010.  Project “Magnitude derivation and regression analysis”.


CONFERENCES AND PAPERS PRESENTED
 
2011 –  International Union of Geodesy and Geopysics, Melbourne, Australia 27th June – 09th July.  Paper presented: Long-range earthquake triggering near Tobago, West Indies: precursory indicators

 2011 –  Soufrière Hills Volcano – Fifteen Years On….. 04th – 08th  April.

 2010 – Seismological Society of America Annual Meeting held in Portland, Oregon 21st-24th April.  Paper presented: Tobago 2011: A prospective case for Operational Earthquake Forecasting

 2009SeismCare Conference Martinique 22-24 June, 2009. Tobago and Earthquakes

 20074th Geological Conference & Exhibition, “Caribbean Exploration – Planning for the Future” June 17-22, Hilton Hotel, Trinidad, organised by the Geological Society of Trinidad and Tobago.  Papers presented: Recent onland Trinidad earthquakes and their implications. Hydrological effects of the 1997/04/22 Tobago earthquake.

2007European Geosciences Union General Assembly, Vienna, Austria session Earthquake prediction: what can be done with the best science available? Poster Presented: Temporal changes in the cumulative piece-wise gradient of a variant of the Gutenberg-Richter relationship, and the imminence of extreme events"
 
2006 - Soufrière Hills Volcano – Ten Years On….. Paper Presented:
Earthquake-volcano stress coupling and interactions at the Soufrière Hills volcano

 2005Special Two Day Conference on Earthquake Engineering of the Caribbean Division of the Institution of Structural Engineers, Mount Irvine Bay Hotel, Tobago.  Paper Presented: Tobago and Earthquakes

 Seismological Society of America annual meeting held in Lake Tahoe, Nevada.  Papers presented: 

   i. Temporal changes in the cumulative piece-wise gradient of the Gutenberg-Richter relationship, and the imminence of extreme events.

   ii. Magnitude production balance, and recent failed San Andreas earthquake forecasts

 APPETT’s 18th Annual Technical Conference on Engineering Infrastructure, Planning and Development for Disaster Preparedness and Mitigation. Paper presented: Magnitude Production Balance From The Piece-wise Gradient Of The Gutenberg-Richter Law And Earthquake Forecasting.  In the presentation, the technique was applied to Trinidad earthquake data. 8pp

 2003 - Seismological Society of America annual meeting held in San Juan, Puerto Rico.  Paper presented: Earthquakes near Tobago, and the Vema Fracture Transform. 13pp. 

 1993 - Caribbean Conference on Earthquake Windstorms and Floods.  Paper presented: Attenuation of seismic waves in the Trinidad and Tobago area.

 1991 - Geological Society of Trinidad and Tobago.  Paper presented: Evidence for the existence of the El Pilar Fault in Trinidad.

 1989 - United Kingdom Geophysical Assembly, University of London, Egham, England.

 1981 - Southwestern University, Dartmouth, Massachusets, U.S.A.

Latchman, J., Robertson, R.E.A., Lynch, L. (2007). Recent onland Trinidad earthquakes and their implications. 4th Geological Conference & Exhibition (GSTT), Port of Spain Trinidad. Paper.

Latchman, J, Robertson, R.E.A., Lynch, L. (2007). Hydrological effects of the 1997/04/22 Tobago earthquake. 4th Geological Conference & Exhibition (GSTT), Port of Spain Trinidad. Paper.

Latchman, J, Morgan, F.D., Aspinall, W.P. (2007). Temporal changes in the cumulative piece-wise gradient of a variant of the Gutenberg-Richter relationship, and the imminence of extreme events. European Geosciences Union General Assembly, Vienna, Austria. Poster.

Fournier N, Lynch L, Robertson R, Latchman J, Mohais R and Ramsingh C (2007): Multi-Hazards Geophysical Monitoring Through the Eastern Caribbean Islands arc: Strategy, Challenges and Future Development. AGU Joint Assembly, Acapulco, Mexico. Paper.