W.W. Chadwick Michael Poland D. Geist Sigurjon Jonsson 2008 <p><span id="ctl00_MainContent_PaperItem_snippet">We use radar interferograms and GPS observations to constrain models of magma accumulation and faulting at Sierra Negra volcano, Gal&aacute;pagos, during the years before its 2005 eruption. The data have shown ~5 m of pre-eruption uplift and multiple trapdoor faulting events on an intra-caldera fault system. We find the pattern of uplift to be consistent with an inflating sill at 2.2 km depth under the caldera. Our deformation modeling and stress-change calculations suggest that the inflating sill triggered faulting on an inward- dipping thrust fault and that the faulting in turn relieved the pressure within the sill. This sill-fault interaction tends to thicken the sill and limit its lateral extent within the area bounded by the fault.</span></p> application/pdf en Deformation and stress-change modeling at Sierra Negra volcano, Galapagos, from ENVISAT INSAR and GPS observations text