Combining magma flow models and deformation measurements to understand magma ascent at silicic volcanoes

火山变形可能是由与岩浆运动和演化有关的广泛过程引起的。可检测到的过程类型取决于测量方法的时间和空间分辨率。到目前为止，卫星雷达测量最常捕捉到与水库有关的过程，模式源深度约为5公里(Ebmeier等人，2018年)。在火山导管附近进行的全球定位系统或倾斜测量更有可能捕捉到与岩浆运输有关的瞬时信号，但通常被模拟和解释为浅层岩浆储集层的膨胀或收缩(Hautmann等人，2009年)。最近，剪应力被确定为变形的另一个来源(Neuberg等人，2018年；Marsden等人。2019年)，其中考虑了浅层硅质管道系统中的岩浆流动。因此，变形模型现在可以描述深部储集层增压和浅层岩浆上升之间的一系列过程。到目前为止，大多数模型都将岩浆视为液体，其体积变化可以解释地表位移。在这个项目中，我们打算将变形模型和岩浆流动模型结合起来，将三相流体流动(熔体、晶体、挥发分)、结晶加压(二次沸腾)、脱气和放气以及热边界层纳入岩浆过程模型(Marsden等人，2019年)。这些岩浆作用影响不同深度可能的粘度范围，以及作用于储集层深度和浅层管道水平的压力范围。通过将浅层岩浆流动和岩浆过程的模拟与源自储集层深度的变形模式相结合，该项目将获得对硅质火山各种旋回行为的新见解。火山在多个空间尺度上的循环行为和变形得到了很好的记录，例如西印度群岛蒙特塞拉特的苏弗里尔山和厄瓜多尔的通古拉瓦。。对于这两座火山，我们可以获得大量的数据集，这些数据集将构成调查的数据库，但还将考虑地震活动和岩石学数据等其他数据集。

"Volcanic deformation can be caused by a broad range of processes related to the movement and evolution of magma.The type of processes detectable depends on the temporal and spatial resolution of the measurement method. Satellite radar measurements have so far most often captured reservoir-related processes, with a modal source depth of ~ 5km (Ebmeier et al., 2018). GPS or tilt measurements made near the volcanic conduit are more likely to capture transient signals associated with magma transport, but have been often modelled and interpreted as inflation or deflation of a shallow magma reservoir (Hautmann et al., 2009). More recently, shear stress has been identified as an additional source of deformation (Neuberg et al.2018; Marsden et al. 2019) which takes magma flow in shallow, silicic conduit systems into account. Hence, deformation models can now describe a range of processes between the pressurization of deep reservoirs and shallow magma ascent. So far, most models treat magma as a liquid, with a volume change that can account for surface displacements. In this project we intend to combine deformation models and magma flow models to incorporate three-phase fluid flow (melt, crystals, volatiles), pressurization through crystallization (second boiling), degassing and outgassing, and thermal boundary layers into models of magmatic processes (Marsden et al., 2019). These magmatic processes affect the possible range of viscosities at different depths, as well as the range of pressures that can act at reservoir depth and shallow conduit level.By combining the modelling of shallow magma flow and magmatic processes with the deformation patterns originating at reservoir depths , this project will gain new insights into the large variety of cyclic behaviours of silicic volcanoes. Examples of volcanoes with well-documented cyclic behaviour and deformation on multiple spatial scales include Soufriere Hills in Montserrat, West Indies and Tungurahua, Ecuador. . For both volcanoes we have access to extensive data sets which will form the data base for the investigation, but further data sets such as seismicity and petrological data will be taken into account as well.