CAREER: Deciphering Cavitation in Fluid-Filled Cracks and its Induced Seismicity through Integrated Physical Modeling

岩浆经常沿着裂缝(称为“岩脉”或“岩床”)在火山下面的地下流动，了解它们的物理性质对于了解火山是如何工作的很重要。有人认为，岩床或岩脉的快速增长会导致岩浆中的气泡突然破裂，导致围岩破裂和火山震动。如果这一点得到证实，监测这些震动将使科学家能够实时跟踪堤坝的生长，这将有助于他们预测喷发的时间和规模。在这个职业项目中，Roohollah Askari博士将进行实验室实验，使充满流体的裂缝中的气泡生长和坍塌，他将使用高速摄影和其他技术监测由此产生的震动和裂缝增长。他还将使用数学技术来证明，他的实验室实验的发现适用于火山下的岩床和堤坝，当然，它们要大得多，由不同的材料组成。阿斯卡里博士和他的团队(包括教师)还将根据这些实验制作几个教育视频，他将在他的实验室接待来自波多黎各的大学生，这样他们就可以和他自己的学生一起学习实验技术。裂缝(岩床和堤坝)对岩浆运输有很大贡献，通常是优先流动的路径。因此，了解岩浆裂隙扩展的动力学及其诱发的地震活动对于估计岩浆运移、监测新裂隙的发展和预测即将到来的喷发至关重要。空化引起的气泡-岩浆相互作用对裂纹的动力学和扩展有重要影响。虽然岩浆中的空化和气泡成核已被广泛研究，但考虑到裂隙流体与壁面之间的复杂相互作用，对充液裂隙中的这些现象知之甚少。强烈到足以破坏裂隙壁、产生次裂隙并在地震中被探测到的冲击波是岩浆裂隙中空化的另一种可能结果。了解这一过程对于预测副堤坝或基床何时可以从先前存在的堤坝或基床发展起来至关重要。在这个职业项目中，Askari将开发两个模拟设备并进行一系列实验，以破译1)影响充液裂缝中空化的基本因素，2)随后的亚裂缝扩展机制，以及3)诱发地震活动。该项目将通过为波多黎各大学的学生提供暑期研究实习机会，促进来自代表性不足群体的学生的参与。将与教师和教育专业人员合作，开发、评估和更新以实验为特色的教学视频，并与教师和教育专业人员合作。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。

Magma often moves through the ground beneath volcanoes along cracks (called 'dikes' or 'sills'), and understanding their physics is important for understanding how volcanoes work. It has been suggested that rapid growth of sills or dikes causes gas bubbles in magmas to collapse suddenly, causing cracking of the surrounding rock and volcanic tremors. If this is proven, monitoring these tremors will allow scientists to track dikes in real time as they grow, which will help them forecast the timing and size of eruptions. In this CAREER project, Dr. Roohollah Askari will conduct laboratory experiments to make bubbles in fluid-filled cracks grow and collapse, and he will monitor shaking and crack growth that result, using high-speed photography and other techniques. He will also use mathematical techniques to show that the discoveries from his laboratory experiments apply to sills and dikes under volcanoes, which are of course much larger and made of different materials. Dr. Askari and his team (including teachers) will also produce several educational videos based on the experiments, and he will host college students from Puerto Rico in his laboratory so they can learn experimental techniques along with his own students.Cracks (sills and dikes) contribute significantly to magma transport, often serving as preferential flow paths. Thus, understanding the dynamics of magmatic crack growth and its induced seismicity is crucial for estimating magma transport, monitoring the development of new cracks, and forecasting upcoming eruptions. Crack dynamics and growth may be affected significantly by bubble-magma interaction caused by cavitation. Although cavitation and bubble nucleation in magma have been studied generally, comparatively little is known about these phenomena in fluid-filled cracks, given the complex interaction between the crack fluid and walls. Shock waves that are strong enough to damage the crack walls, create sub-cracks, and be detected seismically are another possible outcome of cavitation in magmatic cracks. Understanding this process is critical to predicting when sub-dikes or sills can develop from a preexisting dike or sill. In this CAREER project, Askari will develop two analog apparatuses and conduct suites of experiments to decipher 1) the fundamental factors influencing cavitation in fluid-filled cracks, 2) the subsequent sub-crack growth mechanism, and 3) induced seismicity. This project will promote the engagement of students from underrepresented groups by offering summer research internships for students from the University of Puerto Rico. Instructional videos featuring the experiments and targeting pre-college and college-level students will be developed, assessed, and updated, in collaboration with teachers and education specialists.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.