| The surface velocity field around plate boundaries and active faults contains information on a wide variety of processes and conditions, including the long-term fault slip rate, rheological properties of the crust and upper mantle and earthquake processes. Extracting this information requires not only high precision geodetic data, but also accurate models reflecting the critical properties of the crust and upper mantle, allowing us to relate the measurements (i.e., strain and strain rate) to the driving forces. The surface velocity field across two active plate boundaries was measured using high precision GPS geodesy and a combination of analytical elastic half-space models and numerical finite element modeling techniques were used to estimate lithospheric and fault parameters.; The surface velocity field and modeling results for southern Iceland indicate that this divergent plate boundary has a complex pattern of strain accumulation due to its propagating nature. Strain accumulation is partitioned between the Western and Eastern Volcanic zones, whereby the spreading rate increases and decreases to the southwest, respectively.; The surface velocity field and modeling results for the Central America, indicate that collision of the aseismic Cocos Ridge results in high degrees of coupling along the plate boundary. Strain is distributed in the upper plate across the forearc and back arc, resulting in terrane migration away from, and orogeny and subduction polarity reversal inboard of the rigid indenter. |
