COCONet: An Opportunity for Strengthening Disaster Risk Reduction

in the Eastern Caribbean

LLOYD LYNCH

Seismic Research Centre

University of the West Indies

St. Augustine

Trinidad and Tobago

2011 COCONet NetworkJune 28-29, 2011

Selected Disastrous Geologic Events in the Caribbean in the Last 110 years

Event Date Country Fatalities No Affected Damage

Volcanic Eruption 08/05/1902 Martinique 30000Volcanic Eruption 08/05/1902 St. Vincent 1670Earthquake 14/01/1907 Jamaica 2000Earthquake 25/05/1972 Nicaragua 6000 300000 2968Earthquake 08/10/1974 Antigua/Barbuda 0 4200 61Earthquake 29/05/1976 Guatemala 23000 2550000 2147Earthquake/Tsu 4,8/08/1946 Dom Rep 1700?Volcanic Eruption 07/06/1985 Colombia 22000 200000 465Earthquake 07/06/1985 Mexico 8000 150000 6216Earthquake 08/06/1986 El Salvador 1200 520000 1352Pacific Tsunami 14/06/1992 Nicaragua 116 40500 30Volcanic Eruption 19/07/1995 Montserrat 19 12000Earthquake 21/06/1999 Colombia 1,185 559,401 1,580Earthquakes 23/06/2001 El Salvador 1159 1412938 1518Earthquake 12/01/2010 Haiti 270000 3000000 12000

Sources:EM-DAT/OFDA/CRED/ECLAC/IDB

“The number of attempts to synthesize the tectonic framework of the Caribbean are infinite as are the number of different frameworks that have been suggested….In terms of the plate tectonic revolution in earth science it would be very much preferable if the Caribbean area and the Bahamas did not exist.”

Quote from F. Nagle, Caribbean Geology, Bulletin Mar. , Sci, 1970

Caribbean Geodynamics Setting

[after, e.g., Jordan, 1975; Adamek et al., 1988; Holcombe et al., 1990; Mascle and Letouzey, 1990; Pindell and Barrett, 1990; Heubeck and Mann, 1991; Mann et al., 1995; Flinch et al., 1999; Weber et al., 2001]. Bathymetry from Smith and Sandwell [1997]. Subduction rates from DeMets et al. [2000] and Weber et al. [2001].

The Quill, St. Eustatius

The Bottom, Saba

Mt St. Catherine, GrenadaKick ‘em Jenny The Soufriere, St. Vincent

Sulphur Springs, St Lucia

Montagne Pelee, Martinique

Morne Aux Diables, Dominica

Volcanoes of the Eastern Caribbean

La Soufriere, Guadeloupe

Soufriere Hills, MontserratNevis Peak, Nevis

Mt. Liamuiga, St. Kitts

Existing seismic stations that are already contributing and regional stations that could potentially contribute to CTEWS – Global View, 207 Stations

Subset of Intermediate Period and Broadband Instruments in Caribbean and adjacent Regions (2008)

-8 5 W -8 0 W -7 5 W -7 0 W -6 5 W -6 0 W

-8 5 W -8 0 W -7 5 W -7 0 W -6 5 W -6 0 W

Longitude

1 0 N

1 5 N

2 0 N

2 5 N

Lat

itu

de

1 0 N

1 5 N

2 0 N

2 5 N

Caribbean earthquakes 1 Historical 1530-1964

Seismic Research UnitThe University of the West IndiesSt. AugustineTrinidad

Tel 868 662 4659 Fax 868 663 9293 e-mail sruuwi@tstt.net.tt

-8 5 W -8 0 W -7 5 W -7 0 W -6 5 W -6 0 W

-8 5 W -8 0 W -7 5 W -7 0 W -6 5 W -6 0 W

Longitude

1 0 N

1 5 N

2 0 N

2 5 NL

atit

ud

e

1 0 N

1 5 N

2 0 N

2 5 N

Caribbean earthquakes The instrumental Period

This slide shows earthquakes since 1964. Note that although there is far greater detail, the general pattern is the same

Plate Dynamics in the Eastern Caribbean

Oblique Collision

Transpression

Eastern Caribbean seismicity

p.72

Eastern Caribbean Earthquake Statistics

Mag. (Mw)

Freq. (Year)

Since (# of Evts.)

≥5.3 4 1950 (250)

≥ 5.8 1 - 2 1950 (77)

≥6.3 1/2 1910 (58)

≥ 6.8 1/8 1810 (25)

≥7.3 1/15 1810 (13)

≥7.8 1/80 1690 (4)

≥8.0 1/270 ? 1530 (2)

Expected Frequency based on 2009 study of boxed area

(12-14 N)

Seismotectonic Source Zones along the eastern Boundary of the Caribbean Plate

EC Eqs. with M>5.9 (1502-2007) and PGA Hazard Map (RP=475 yrs)

2009 Revision of East. Caribbean Hazard Maps depicting Spectral Acceleration at 0.2 and 1.0sec for Return Period of 2475 years

Map of Stations Contributing Data to the Tsunami Warning Network

http://rmsismo.uprm.edu/Estaciones/estatus.php?maptype=1&stat_type=100

Eastern Caribbean Broadband Stations

Total = 32 Stns

V VSAT Comms

V

V

V

VV

V

V

VV

V

Planned VSAT Stns

Planned Internet Stns

Surface elevations for the Lesser Antilles Scenario (in source region which produced M7.5+ 1843 event)

Moment Tensor Solutions

• Used in the definition of sources

Generalised structure map of the Southern Caribbean (After Pindell et al 2007)

Tectonic setting of Trinidad showing results of previous GPS studies (with stable S. America as a reference frame). Green vectors from Perez et al. (2001); orange vectors from Trenkamp et al. (2002); blue vectors from Weber et al. (2001). [After Soto et al]

Tectonic setting of Trinidad

shortening and overthrusting,

Arc-parallelextension.

Transition zone

After FEUILLET ET AL.

Key Considerations

• In the Eastern Caribbean , several populated centres are (may be) threatened by near –surface, potentially active faults

• GPS has the potential to identify such faults and help is assessing the contribution to earthquake hazard.

• Population centres are also threatened by large subduction earthquakes

• Study of the distribution of strain rate through GPS could help to resolve uncertainty of the earthquake source parameters.

• The Eastern Caribbean is at risk from “short fused” tsunamis an subsidence surge

• GPS could add another dimension to the Coastal Hazard and Tsunami Early Warning System

• More than 300,000 West Indians live and/or work along the flanks of live volcanoes .

• GPS is currently used to develop and maintain a database of flank elevation

TYPICAL SRC ISLAND NETWORKS

Example 1: DOMINICA

Installed 3 cGPS (red stars) at DOMI, ROSS & PNVL

Total of 15 benchmarks (red dots) periodically measured.

Measurement interval ~ 2 hrs

Recording rate ~ 1 sec

Morne Aux Diables - N. Dominica

Since June 2009 to present, there has been elevated seismic activity or ‘seismic unrest’ beneath Morne Aux Diables.

GPS surveys have been more frequent, in February 2010 & again in October 2010. Networks utilized ROSS &PNVL as base stations and benchmarks measured ~ 2 hrs.

So far, results highlight no clear changes in co-ordinate location or baseline length.

Qu ickTime™ and a decompressor

are needed to see th is p ictu re.

Typical GPS benchmarks are:

1/ 10 cm long pins

2/ 15 cm metal screw-threaded rods

Both types drilled & epoxied onto concrete roofs

Eg THBD pin at Thibaud village (on Health Centre roof)

Morne Aux Diables complex from Morne Diablotins

SRC GPS Network

SRC, OSVG and OSVM operate and share a growing Network of cGPS stations in the eastern Caribbean (currently 11 stations). Files are sampled at 1 hz and FTPed in hourly files to servers for redistribution to the wider community of stakeholders. SRC uses the network primarily for referencing for the campaigns of volcano deformation networks but as the network grows it is increasingly providing more insights on regional plate dynamics.

Eastern Caribbean cGPS Stations

2007 GPS Time Series - ALBI, Antigua SVGB, St. Vincent & ANTG, Antigua

ANTG

SV

GB

AL

BI

Priorities/Goals

• Reduce Downtime;

• Expand the network;

• Characterize and reduce noise;

• Add redundancy;

• Improve latency;

• Improve overall quality of next generation stations, particularly stability of site/monument;

• Improve data archiving/processing infrastructure;

• Establish QQ regime and visualization tools;

• Integrate into EW Systems;

• Bootstrap research program.

Station Siting

• St Barts vE• Anguilla N*• St Kitts vE• St. Marteen E*• Redonda NP• Montserrat vPF• Antigua vERF*• Barbuda vNS*• Guadeloupe vE*• Dominica (2) vE, NF*• Martinique (4) vE*,vNF**• St. Lucia vNF*• St. Vincent (2) vE*• Barbados vE*• Mustique NF• Carriacou vNF*• Grenada vE*• Tobago (2) vE, E*• Trinidad (5) E*, E**

Legend

• V – VSAT Comms

• E – Existing

• N – Not in Existence

• R – To be Refurbished

• F – Funded