The dynamics of magma differentiation in the Grenadines, Lesser Antilles arc

Description: This research was driven by the limited understanding of the sub-volcanic architectures of Lesser Antilles volcanoes, which has hindered scientists’ ability to interpret pre-cursory activity. Volcano behaviour is ultimately a surface expression of the dynamics of magmatic systems in the underlying crust. Though these systems cannot be directly observed, insight into their configuration and internal conditions can be gained by studying the petrology of erupted products. This reasoning was applied to five volcanic centres of the Grenadines: Bequia, Kick-‘em-Jenny, Kick-‘em-Jack, Petit St. Vincent and Île de Ronde. The textures and compositions of erupted lavas (derived from shallow eruptible magma storage reservoirs) and crustal xenoliths (samples of the crystalline roots of the entire magmatic system) were analysed to reconstruct the depth and distribution of magma below the surface.

Principal Researcher: Michal Camejo-Harry
Supervisors: Richard Robertson and Thomas Christopher

Modelling of the Montserrat Geothermal System

Description: Geothermal energy is heat derived below the earth’s surface which can be harnessed to generate clean, renewable energy. This energy can be obtained by drilling wells that tap heat energy in the form of high temperature brines from the shallow crust. Geothermal development continues to take place in Caribbean volcanic islands. Of the eleven volcanic islands, Montserrat has been under active development and continues to strive to harness this energy effectively and efficiently, through active development of the geothermal system (2 wells drilled already (MON1 and MON2) (EGS, 2014) and one currently being drilled (MON3) within the geothermal system) and through continuous research. As such, this research project is focused on the geothermal system of Montserrat. It aims to investigate various exploration studies conducted on the island which have all contributed to the placement of the three geothermal wells. The geophysical studies conducted include magnetotellurics (Ryan et al., 2009), gravity (Hautmann et al., 2013) and seismic tomography (Shalev et al., 2010).

Each technique resulted in the interpretation of a particular physical property (resistivity, density and elastic moduli respectively). However the non-uniqueness of the geophysical models and interpretations lead to unavoidable uncertainties when utilising geophysical data. To help alleviate this problem, an approach called joint-interpretation is utilised where several complementary geophysical data sets, which measure different physical properties, are interpreted together to determine a coherent physical model which is consistent with all data sets (Pommier and Garnero, 2014). Ryan et al. (2014) used the high resolution seismic tomography data (Shalev et al. 2010) together with well log data to image the geothermal reservoir in Montserrat. By investigating and combining the various geophysical datasets, this research project aims to develop a three-dimensional model of the geothermal system which estimates thermal structure and likely fluid flow pathways through the system. This approach leads to a more robust interpretation and helps to determine the correct interpretation of each of the geophysical data sets.

Principal Researcher: Racine Basant
Supervisor: Graham Ryan

Development, testing, and application of a low-cost technology sulphur dioxide monitor as a tool for use in a volcanic emissions monitoring network

Description: Sulphur Springs in Saint Lucia is a highly active geothermal area, located within the Soufrière Volcanic Centre, and is a park widely visited by tourists and locals. It is also a current source of continuous volcanic emissions via its many fumaroles and bubbling pools, warranting concern by residents and visitors to the park regarding the effects of exposure to these gases. In this study we introduced a novel SO2 measurement system for the monitoring and quantification of ambient levels of airborne volcanic SO2 using low-cost technology. This work involved the extensive production of low-cost, active SO2 samplers, as well as field examination in tandem with a standard commercial sampler (SO2 diffusion tubes). It also incorporated community involvement in the volcanic monitoring process as non-professional users of the instrument and subsequent analysis of the samples.

Preliminary monitoring results obtained from the low-cost samplers reflected that obtained from the diffusion tubes in identifying the areas in the Park exposed to higher concentrations of ambient SO2. The instruments feasibility, for non-professional use and application in volcanic settings as a volcanic monitoring and/or volcanic hazard awareness tool, was also assessed.

Principal Researcher: Viveka B. Jackson
Supervisor: Erouscilla Joseph

The Effect of Shallow Water Aquifers on Ambient Seismic Noise

Description: Seismic shear wave velocity (Vs) and shear wave attenuation (Qs) are factors that contribute to the level of shaking structures experience in a given earthquake. Water in sedimentary layers may cause physical changes in rocks, e.g. its density, that can alter these parameters and, therefore, impact the seismic hazard. In island settings, assessing the seismic hazard in areas near the coast and those above aquifers must include the contribution made by water in sedimentary layers; the subsurface water in an area can be fresh water or, saline due to salt water intrusion. Port-of-Spain and Diego Martin are areas in Trinidad that would be subject to this phenomenon.

The aim of this study is to determine the local effects, if any, of shallow aquifers (in both saline and fresh water environments) on horizontal to vertical Fourier amplitude spectral ratio (HVSR) curves. The proposed area of study is the Diego Martin Valley, Trinidad which transects the north coast peninsula encompassing both fluvial and marine environments thereby being able to capture the effects of both saltwater and fresh water.

Principal Researcher: Jevan Manzano
Supervisor: Ilias Papadopoulos

Seismic Site Effect Study of the Diego Martin Valley

Description: The Diego Martin Valley is densely populated, 2,790 per km2, and is one of the largest residential districts in Trinidad and Tobago. For a given earthquake, seismic intensity reports from the Diego Martin Valley are generally anomalously high. Even when compared with other areas in the north-western peninsula (western Northern Range), as well as other densely populated areas the intensity reports often show that the Diego Martin Valley experiences higher intensities. This research aims to identify the geophysical reasons for these observations.

The main hypothesis is that the Diego Martin Valley Geology and the Geometry of its Geomorphology, amplify ground motion.  This is due to high impedance contrast between, thick unconsolidated and often saturated sediments (the valley alluvium and reclaimed coastal mangrove), and the underlying Rock Strata (Chancellor Schists/Limestone, Maracas Schists and Maraval Limestone), as well as a possible focusing effects of the geometry of the interface between the sediments and the rock strata of the valley which may also play a part in amplifying ground motion. The project aims to produce a model of the Diego Martin Valley illustrating the fundamental frequency/period of the soil, shear wave velocities, and thicknesses of the sediments from the surface to the underlying rock formations based on HVSR (Horizontal to Vertical Spectral Ratio) recordings and MAM (Microtremor Array Measurements).

Principal Researcher: Kafele Reddock
Supervisor: Ilias Papadopoulos

Evaluating Communication for Volcanic Emergency Management at The UWI Seismic Research Centre

Description: During periods of volcanic unrest, emergency managers in nine Eastern Caribbean territories depend on scientific information from The UWI Seismic Research Centre (UWI-SRC) to guide their decision making. The level of situational awareness achieved by civil authorities is due in large part to the quality of information they receive. This study evaluates The UWI-SRC’s information creation process and the Centre’s delivery of scientific information during periods of elevated volcanic activity.

A developmental approach to this evaluation included semi-structured interviews of scientists and communication professionals at The UWI-SRC as well as surveys of regional emergency management personnel. When completed this research would offer suggestions for optimising information dissemination for volcanic emergency management throughout the Lesser Antilles. This work will also benefit the advancement of communication best practice among agencies responsible for protecting life and property in the event of volcanic unrest and/or eruption in the Eastern Caribbean.

Principal Researcher: Omari Graham
Supervisors: Richard Robertson and Stacey Edwards

Evaluating Seismic Risk Communication in the Diego Martin Valley

Description: This project aims to evaluate the current risk communication strategies used by The UWI Seismic Research Centre and to determine effective methods of communicating information obtained by the scientists to the Diego Martin Regional Corporation. In addition, to discuss with the community of the Diego Martin Valley the most effective adaptation of these strategies in order to maximize the effect of the risk communication in their daily routine, as they are preparing for the next major event. The Diego Martin Valley was chosen as the study site due to the unique geology which is believed to be the cause for residents experiencing higher intensity earthquakes than nearby areas.

Principal Researcher: Thalia Thomas
Supervisor: Ilias Papadopoulos