9726024 Hamburger This collaborative proposal (Indiana University and UCAR) seeks funds to support a study of crustal deformation associated with magmatic activity on two active volcanoes in the Philippines, Pinatubo and Taal. The two volcanoes offer an opportunity to examine magma dynamics associated with two neighboring, but very distinct volcanic systems - an explosive, subduction-related, dacitic stratovolcano (Pinatubo) and an extensional basaltic-andesitic volcano complex (TAAL). The PIs will use precise measurements of vertical and horizontal movements of the Earth's crust using state-of-the-art Global Positioning System (GPS) measurements, including a newly developed, low-cost, single-frequency volcanic monitoring system currently in development by C0-PI Meertens. This proposal requests funds for data collection and analysis; funds for the GPS instrumentation are requested in a second, companion proposal to the NSF instrumentation & Facilities program. Among the principal scientific objectives of the project are: (1) improved understanding of the magmatic systems associated with active volcanic processes at the two volcanoes; (2) analysis of long-term post-eruptive processes in the aftermath of Pinatubo's cataclysmic volcanic eruption of 1991; (3) refined spatial control on magma movement (at Taal) via development of a real-time volcanic monitoring system; (4) identification of spatial and temporal interactions between tectonic structures and volcanic systems - the Philippine Fault in the case of Pinatubo, and the Marikina Fault for Taal; and (5) development and testing of new, state-of-the-art crustal deformation measurement systems for volcanic monitoring. These include use of real-time kinematic (RTK) measurements along dense profiles on the volcanoes flanks, and a first field test of newly developed, single-frequency GPS volcanic monitoring system. Specifically, the PIs research plan includes the following experiments: (1) high-precision (sub-cm accuracy) static GPS meas urements at Pinatubo, Taal, and fault-monitoring networks around the Philippines and Marikina faults (Year 1); (2) lower-precision (1-2 cm accuracy) RTK measurements along dense profiles on the two volcanoes (Year 1); (3) development of a continuous, three-station, real-time telemetered, high-precision (dual-frequency) GPS network around Taal Volcano (Year 1); (4) analysis of data from static and real-time networks using Bernese software; (5) installation and field testing of a 10-station array of single-frequency, cm-level-precision GPS stations around Taal (Year 2); and (6) analysis of data from the dual and single-frequency networks, and comparison with a parallel system in development by colleagues at the University of Savoie (Years 2-3).
