CAREER: Seismo-acoustic signatures of volcanic unrest and eruption: Local, regional, and remote

地震学和声学是定量火山喷发过程的互补地球物理方法，两者现在都在火山监测和减灾中发挥着关键作用。地震数据记录的是通过固体地球传播的弹性波场，而声学数据记录的是通过流体大气传播的声波场。总的来说，在火山爆发之前、期间和之后记录的地震和声学信号让我们了解了火山是如何工作的，并使火山监测科学家能够预测和评估火山爆发。地震数据目前构成了大多数火山监测系统的支柱。火山喷发时的地震信号捕捉到与爆发有关的岩浆运输和快速减压。次声是一种频率低于20赫兹的声波，是人类听觉的低频极限，是一种较新的技术，可以精确地限制爆炸爆发活动的时间和持续时间。来自大型爆炸喷发的次声可以在大气波导中传播数千公里，次声传感器网络有时是唯一记录爆炸喷发的地面技术。该项目支持一项为期5年的综合研究计划，内容涉及火山动荡和喷发的地震声学特征的来源、传播、远程探测和量化。该研究项目将与加州大学圣巴巴拉分校地球科学系的一系列本科和研究生教育活动相结合。该项目将从瓦努阿图、墨西哥和智利的活火山收集新一代多参数地震声场数据，这些活火山距离震源有15公里、15-250公里和250公里。同时，首席研究员将开发一系列计算密集型数据处理方法、建模和反演策略，以系统地挖掘大型火山地震声学数据集，并测试关于这些波场的来源和传播的多种科学假设。具体而言，他将研究：(1)火山爆发声源指向性；(2)震声波的划分、转换与耦合；(3)非线性次声传播；(4)地形和大气结构（主要是风和温度）对火山爆发的线性和非线性次声传播的影响；(5)区域和远程次声和地震台网探测、定位、表征和编目爆炸性喷发的能力。这项工作有可能极大地推进火山地震声学领域，弥合地方和区域到全球尺度研究之间的差距。瓦努阿图油田部署将结合地面宽带地震和次声网络、多种新型机载次声系缚气球（浮空器）采集系统、3D航空（无人机）成像和其他多参数数据。每个地球物理实地实验团队将包括来自加州大学圣巴巴拉分校的五名本科生和两名研究生。这些实验将涉及来自美国、新西兰、瓦努阿图、墨西哥和智利的多名研究人员和研究生的重要国际合作。在现场，他们将从新颖的360度、具有虚拟现实功能的摄像机、无人驾驶飞行器和其他系统中收集地理参考视频数据，从而为虚拟实地考察练习创建丰富的沉浸式材料，从而将火山地球物理实地考察和科学发现的兴奋感分享给加州大学圣巴巴拉分校和其他地方的普通教育本科生。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Seismology and acoustics are complementary geophysical methods for quantifying volcanic eruption processes and both now play a critical role in volcano monitoring and hazard mitigation. Seismic data record elastic wavefields propagating through the solid Earth, while acoustic data record acoustic wavefields propagating through the fluid atmosphere. Collectively, seismic and acoustic (seismo-acoustic) signals recorded before, during, and after eruptions inform our understanding of how volcanoes work and enable volcano monitoring scientists to forecast and assess eruptions. Seismic data currently form the backbone of most volcano-monitoring systems. Seismic signals at erupting volcanoes capture magma transport and rapid depressurization associated with explosive eruptions. Infrasound, acoustic waves with frequencies below 20 Hz, the lower-frequency limit of human hearing, is a newer technology, and provide accurate constraints on the timing and duration of explosive eruptive activity. Infrasound from major explosive eruptions can propagate for thousands of kilometers in atmospheric waveguides and infrasound sensor networks are sometimes the only ground-based technology to record an explosive eruption. This project supports a 5-year comprehensive research program on the source, propagation, and remote detection and quantification of the seismo-acoustic signatures of volcanic unrest and eruption. This research program will be integrated with a range of undergraduate and graduate educational activities at the Department of Earth Science, University of California, Santa Barbara.This project will collect next-generation, multi-parametric, seismo-acoustic field data from active volcanoes in Vanuatu, Mexico, and Chile at local (15 km), regional (15-250 km), and remote (250 km) distances from the source. In tandem, the lead researcher will develop an array of computationally intensive data processing methodologies and modeling and inversion strategies to systematically mine large volcano seismo-acoustic datasets and test multiple scientific hypotheses about the source and propagation of these wavefields. Specifically, he will investigate: (1) Acoustic source directivity of volcanic explosions; (2) Seismo-acoustic wave partitioning, conversion, and coupling; (3) Non-linear infrasound propagation; (4) The influence of topography and atmospheric structure (primarily wind and temperature) on linear and non-linear infrasound propagation from volcanic explosions; and (5) the capability of regional and remote infrasound and seismic networks to detect, locate, characterize, and catalog explosive eruptions. This work has the potential to dramatically advance the field of volcano seismo-acoustics, bridging the gap between local and regional to global scale studies. The Vanuatu field deployments will combine ground-based broadband seismic and infrasonic networks with multiple novel airborne infrasound tethered-balloon (aerostat) acquisition systems together with 3D aerial (drone) imaging and other multi-parametic data. Each geophysics field experiment team will include up to five undergraduates and two graduate students from UC Santa Barbara. The experiments will involve significant international collaboration with multiple researchers and graduate students from the US, New Zealand, Vanuatu, Mexico, and Chile. In the field, they will collect geo-referenced video data from novel 360 degree, virtual reality capable cameras, unmanned aerial vehicles, and other systems, allowing the creation of a rich immersive material for virtual field trip exercises that will share the excitement of volcano geophysics fieldwork and scientific discovery to General Education undergraduate students at UC Santa Barbara and elsewhere.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.