Understanding Dike Propagation Through Comparison of High-fidelity Coupled Fracture and Fluid Flow Models and Field Observations

在火山喷发之前，岩浆通过地壳上升，最常见的是在被称为“岩脉”的狭窄裂缝中。堤防上涨往往伴随着小地震和地表变形，这可以由地面传感器探测到，在某些情况下还可以由天基传感器探测到。并不是所有的岩墙都会导致喷发；在某些情况下，它们会失速，岩浆固化而不会喷发。为了正确解释地震和形变信号，并提供与社会相关的喷发警告，我们必须了解控制堤坝上升速度的物理和化学过程，它们采取的路径，以及它们是否到达地表。这些过程包括坚硬岩石在堤坝外的阻力和运动，岩浆在堤坝内的流动，堤顶地壳的破裂，以及岩浆在走向地表的过程中冷却时可能发生的固化--所有这些都是相互依存的。西格尔、卢和他们的团队将使用复杂的计算技术以及地面变形和地震数据来模拟夏威夷的堤坝上升，并制定使用这些数据预测夏威夷和世界各地类似火山喷发的指导方针。这项研究将解决国家科学院喷发报告中的重大挑战之一，以推进基于物理学的喷发预测。准确、高保真的堤坝传播模型是了解许多喷发前兆的关键，最终将有助于世界各地的火山观测站进行预测。该项目将利用计算方法的进步，使数值网格能够适应堤坝随着增长而变化的形状。这些进展和其他进展将使他们能够解决：允许堤坝到达地球表面的条件(岩浆粘度、背景温度梯度、水库压力、体积和可压缩性)；可用于基于物理学的喷发预测的与时间相关的地表变形和地震引发的应力扰动；以及决定深层堤坝是聚焦于地壳油藏还是绕过地壳油藏的因素。计算的堤防上升历史和预测的地表变形将与一些喷发前的变形和地震活动观测结果以及实验室模拟实验进行比较。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Prior to volcanic eruptions magma rises through the crust, most commonly within narrow fractures known as “dikes.” Dike ascent is often accompanied by small earthquakes and deformation of the ground surface which can be detected by ground-based, and in some cases space-based sensors. Not all dikes lead to eruptions; in some cases, they stall and the magma solidifies without erupting. To properly interpret seismic and deformation signals and provide societally-relevant eruption warnings, we must understand the physical and chemical processes that control how rapidly dikes ascend, the paths they take, and whether or not they make it to the surface. These processes include resistance and motion of the solid rock outside the dike, the flow of magma within the dike, fracture of the crust at the dike tip, and possible solidification of the magma as it cools during its journey toward the surface - all of which are interdependent. Segall, Lew, and their team will use sophisticated computational techniques together with ground deformation and earthquake data to model dike ascent in Hawaii, and to develop guidelines for using such data to forecast eruptions in Hawaii and at similar volcanoes worldwide. This research will address one of the Grand Challenges in the National Academies ERUPT report to advance physics-based eruption forecasting. Accurate, high-fidelity models of dike propagation are key to understanding precursors to many eruptions and will ultimately facilitate forecasting at volcano observatories worldwide.This project will leverage advances in computational methods that allow the numerical grid to adapt to the changing shape of the dike as it grows. These and other advances will allow them to address: the conditions (magma viscosity, background temperature gradient, reservoir pressure, volume, and compressibility) that permit a dike to reach the earth's surface; the time-dependent surface deformations and seismicity-inducing stress perturbations that could be used in physics-based eruption forecasting; and the factors that determine whether deep dikes are focused toward or bypass crustal reservoirs. Computed dike ascent histories and predicted surface deformation will be compared to observations of deformation and seismicity that precedes some eruptions, as well as with laboratory analog experiments.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.