The Grenadine Islands and the marine environment surrounding the islands were mapped over a five-year span. The project—Grenadines Marine Resource and Space-Use Information System (MarSIS)—involved merging local knowledge with existing scientific data into a geographic information system (GIS). Located in the Caribbean, the Grenadines share an international boundary between Grenada and St. Vincent and the Grenadines, creating numerous challenges for not only collecting data but sharing those data with the residents of the islands. Project geospatial information was collected in a GIS, but Google Earth was used as a way to share the findings on the web and through a series of tutorials and workshops. Though project GIS shapefiles will be made available through the project website, Google Earth was used as a ready delivery tool because it is cross platform, easy to use, and free. Using aftermarket GIS extensions, shapefile layers were exported from ArcGIS into Keyhole Markup Language (KML) layers. Over 400 photographs and videos were geolocated in the project KML. Once the Grenadines marine map was assembled as a KML project, we gave workshops on various islands. From user feedback following the first series of tutorials, we modified the KML by fixing problems, correcting mistaken information, and making the KML project file more understandable. When the project was finalized we put the KML on the MarSIS project web page and sent it as an attachment to the project email list. We traveled a second time to the Grenadine Islands to give another series of tutorials and workshops. We also created a video to help users navigate the project KML.

Most phases of silicic lava dome growth have some associated explosive activity. Tephra produced during this activity have depositional characteristics, grain sizes, and grain shapes that reflect different mechanisms of dome growth and destruction. It is therefore possible to interpret the explosive history of a dome through study of adjacent tephra deposits even though the dome may no longer be present. Five stages of dome growth and their associated tephra deposits are considered here. (1) Crater formation before extrusion of a dome, including phreatic, phreatomagmatic (ph-m), and Plinian pumice eruptions, produces a tephra sequence at the base of a dome consisting of deposits rich in accidental lithic clasts from crater walls, overlain by beds of fine-grained tephra and coarse-grained pumice. (2) Magma pulses during dome growth (ph-m, in part) produce tephra consisting of mixtures of juvenile pumice and clasts derived from the partly solidified dome. (3) Ph-m interaction between new magma and a water-saturated dome produces uniform tephra consisting of angular clasts of dome lava. (4) Explosive eruptions that follow collapse of a gravitationally unstable dome produce tephra that consists of angular, partly pumiceous clasts of dome lava which fragment due to expansion of metastable water after release of confining pressure. (5) Posteruptive destruction of the dome by phreatic eruptions results in pyroclasts consisting of fine-grained, hydrothermally altered clasts derived from dome lavas. Major kinetic processes before explosive dome eruptions are the relatively slow diffusion of magmatic volatiles from magma to fracture planes and foliations within the dome, and the relatively fast diffusion of meteoric water into magma by mechanical mixing. These basic processes control most explosive activity at domes in cases of either expulsion of new magma or collapse of an unstable dome.