Inception, Deployment, Processing and Initial Results

of a Continuous GPS (cGPS) Network Across the

Lesser Antilles Arc: Implications for Caribbean Plate

Geodesy and Volcano Monitoring

Robert WATTS, Richard Robertson, Nico Fournier,

Lloyd Lynch, Machel Higgins & Henry Odbert

Seismic Research Centre, UWI, Trinidad & Tobago

MAIN AIMS OF THIS TALK:

1/ What is the primary role of the SRC ? 2/ Explain our ongoing continuous GPS network for the English –speaking Lesser Antillean islands to help determine plate motion? 3/ Explain our Volcano Monitoring Deformation Networks using the cGPS stations on each island? 4/ Receive advice & criticism from this audience. 5/ To let you all know we would ‘welcome’ any future collaborative ventures in our region.

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Puerto Rico

Trinidad

✕

Kick Em Jenny

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Isle of Montserrat: Soufrière Hills Volcano (SHV) has been erupting for 17 years now – currently has a network of 11 continuously operating GPS stations (mostly Trimble NetRS) supervised in recent years by Dr. Henry Odbert.

★ SHV

Interesting SHV Relationship GPS & Eruptive Stages

5 ACTIVE episodes INFLATION – inactive period

DEFLATION - active period

GPS

SO2

CARIBBEAN PLATE GEODESY

SRC has installed 1 Trimble NetRS cGPS on every island in last few years. Each one collects epochs at 30 sec intervals & then every night 1 days data is downloaded automatically via script and Internet --- sent back to TRINIDAD. Several months worth of data are stored and then processed at SRC using the GAMIT/GLOBK package developed at MIT (USA)

REFERENCE FRAMES:

SRC Network & Montserrat Network: A limited no. of cGPS stations exist around the Caribbean (lack of land!) but we utilize Belize, St. Croix & St. Maarten with the main FIXED point at KOUROU, Guyana.

PLATE VELOCITY MODEL: Utilizes average horizontal velocity calculated from stations near to Montserrat (eg ANTIGUA). Model uses many iterations & statistical relationships between available data (pers. comm. HENRY ODBERT)

Plate Motion Averages 19 mm to ENE generally, Grenada slightly more North. Trinidad: 5 cGPS stations on TnT show opposing trends of motion, is this a major plate boundary? (Weber et al, 2009)

T & T

Antigua

St. Vincent

VOLCANO DEFORMATION GPS SURVEYS

Example 1: DOMINICA 9 potentially active volcanoes

SURVEY TYPE: Rapid-Static Mode 3 Rover Kits Data collection - ONE sec intervals TWO Hour periods

Eg: Morne Aux Diables in North TWO cGPS sites ROSS + PNVL SEVEN rover sites around M.A.D.

SURVEY FREQUENCY: 6 months if possible due to VT earthquake activity since June 2009.

Process with Trimble Business Centre software

Example 2 : ST. VINCENT

Soufriere St. Vincent Volcano:

Previous eruptions in 1970-71 (quiet dome-building) & 1979 (large sub-Plinian explosion). 1 major eruption in May, 1902 (1500 people killed).

SVGB + SVGK are cGPS sites & 6 rover sites

SURVEY FREQUENCY – 1 time every 2 years (if no activity)

cGPS SITE LOCATIONS:

cGPS on Bath Hotel, NEVIS

Rover pin in ST. VINCENT

cGPS in Penville village on flanks of Morne Aux Diables, DOMINICA

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FOUR SRC stations to be part of UNAVCO COCONET datashare project

UNAVCO (NSF funded) International

★

RECENT COLLABORATION WITH CHILEAN COLLEAGUES:

Me & Dr. Alvaro Amigo in front of Cerro Chao flow-front – future volcanology field projects together.

Acting Director of SRC (Dr. Joan Latchman) receiving gift of 2 cGPS instruments for Trinidad from Univ. of Chile (Sergio Barrientos).

SUMMARY

1/ SRC is very open to future collaborations … 2/ SRC is dedicated to monitoring all Caribbean natural hazards. 3/ I am keen to hear criticisms/comments on geodetic monitoring.