The main objective of this project is to add two additional continuous Global Positioning System (CGPS) stations to the existing 8-station CGPS network at Sierra Negra volcano, on the Galapagos island of Isabela. This network, originally installed in June 2002, successfully captured the extraordinary deformation leading up to and during the October 2005 eruption at the Sierra Negra. The eruption was preceded by multiple ?trapdoor faulting? events in the caldera floor, and accelerating inflation that amounted to 2.2 m of uplift in 30 months (?trapdoor faults? are curved faults that bound an uplifted block with a hinge zone on one side, like a trapdoor). More trapdoor faulting, dike intrusion, and subsidence of over 5 m in the caldera were associated with the eruption itself. The two additional CGPS stations will allow the investigators to fill a critical gap in the deformation monitoring, will eliminate ambiguity in satellite radar interferometry (InSAR) scenes that are discontinuous across the fault system, and will help better detection and modeling of the on-going deformation at the volcano. This work is timely because Sierra Negra began to re-inflate as soon as the October 2005 eruption was over and the center of the caldera has already been uplifted by over 2 m. At this rate of inflation, more trapdoor faulting events or eruptions are likely within the next few years. This project will ensure that researchers learn as much as possible from future events at this very active volcano, which is one of the best places on Earth to study the shallow intrusion of magma in space and time.
