Santorini Caldera, in the southern Aegean, is part of a well developed, and very active volcanic system fueled by subduction along the Hellenic arc that is responsible for the largest volcanic eruption in human history (~1650 B.C.). After a long period of approximately 50 years of relative seismic quiescence within the caldera and years of measuring essentially zero deformation, the volcano has recently reawakened with an exponentially increasing inflation signal. This project will deploy a RAPID GPS campaign, upgrade the current continuous GPS network, and includes installation of 2 new continuous stations to capture the time-dependence of inflation. This is a RAPID project because the deformational signal is indeed rapidly evolving, and may continue to proceed non-linearly in the coming months. This signal is essential for understanding the rheologic controls, and will not be sufficiently constrained with the limited continuous data that we currently have. Installation and updating of equipment is essential before the winter months, as the current remote sites currently go down for extended periods because of insufficient solar panels for the dominantly overcast skies. Data obtained through this experiment will be useful for evaluating the ongoing deformation at the Caldera, and in turn, be use for identifying the geometry and precise location of the pressure source. The evolving temporal signature is necessary for identifying how the system develops. As well, it will give a window into the rheologic structure that reacts to the source, and ultimately dictates the likelihood of eruption. The information is invaluable for improving our understanding of eruption dynamics, and is some of the first such information for a very young caldera system This research has immediate impact beyond the volcano geodesy community as the continuous GPS data will serve as an indicator, and thus warning tool, useful for hazard mitigation. Because all continuous data will be immediately available to the public through UNAVCO, other groups will have access to utilizing it for independent scientific, hazard, or educational needs.
In January 2011, after almost 60 years of calm, Santorini volcano reawakened with a number of small earthquakes and rapidly expanding deformation. Through this project, we used the Global Position System (GPS) to measure the movement of 24 points along the volcano to identify the shape and extent of growth. The measurements included repeat sampling of fixed monuments across 19 sites, and the repair and addition of 5 continuous stations that continue to 'watch' the ongoing activity. Between January 2011 and September 2011 (when the GPS experiment was performed), the volcano has extended laterally from a point inside the northern segment of the caldera by about 140 mm. Using the continuous GPS, we've identified that the rate of deformation changes over time, and is largely mimicked by the number of small earthquakes also occurring there. Importantly, we've identified that the source of deformation is not migrating significantly, but remains about 4 km depth. As of Sept. 2011, the volcano expanded by 14 million m3. The source of inflation is likely new magma, and through the newly installed continuous GPS and future field campaigns, we will continue to observe the system. While observations of the current deformation sequence are unprecedented at Santorini, it is not certain that an eruption is imminent as other similar calderas have experienced comparable activity without eruption.
