Displacement of volcanic edifices recorded by geodetic techniques can fluctuate in response to magma motion within the crust. Prior to its 2005 and 2018 eruptions, and during the inter-eruption time period, Sierra Negra volcano, Galapagos Islands, Ecuador, displayed large displacements within its caldera providing insights into the underlying magma movements. In the five-year run-up to its 2018 eruption Sierra Negra, GPS stations captured two successive uplift episodes that were accompanied by increasing numbers of earthquakes nearer the eruption date. The present work develops simplified physical models for magma transport at depth feeding a shallow magma reservoir. We show that when the crust around a growing reservoir is being damaged by increasing pressure due to magma accumulation, the resulting crustal displacement can display two successive uplifts as observed at Sierra Negra prior the 2018 eruption. Additionally, the accumulating damage can account for the observed earthquake count.