EAR-PF Investigating Volcanic Explosion Directivity Using Aerial Infrasound Observations with UAVs

Alexandra Iezzi博士获得了NSF EAR博士后奖学金，在罗宾·马托扎教授的指导下，在加州大学圣巴巴拉分校开展研究和教育活动。次声传感器测量低频声波(低于人的听力极限)，并提供监测和确定爆炸源的详细手段，例如火山喷发造成的爆炸源。然而，这些传感器通常放置在地球表面，只能提供有限的火山爆炸声辐射模式和方向性的样本，从而造成对声源特征的偏差。该项目通过使用一种新的方法来解决这个问题，该方法除了在地面上部署传统的传感器外，还使用多个无人机(UAV)上的传感器收集次声数据。我们的传感器平台和测量将增加我们对经常活动的瓦努阿图亚苏尔火山和一般爆炸源的声学指向性的了解。这里提出的研究有可能彻底改变使用次声仪器监测活火山的方式，目的是提供关于爆炸动力学的独特信息。拟议的新技术将允许在喷发附近的空气和地面上部署次声传感器，以便更好地了解火山源，大大减少对现场人员的风险暴露。该项目是对无人机次声部署的概念验证研究，可以将数据收集扩展到世界各地活火山和人为爆炸源附近以前无法到达的地点。安装在无人机上的次声传感器将从独特的角度记录数据，允许考虑地形影响的声源反演方法以一种以前不可能实现的方式限制爆炸的定向辐射模式。通过采用这些方法，我们还将改进质量流量的计算，这是一个宝贵的监测参数。次声观测将用部署在火山口边缘的多个摄像头确定的弹道轨迹进行验证，我们假设这类似于火山灰、气体和蒸汽排放的方向，可能会对火山附近的人造成伤害。将安装在无人机上的次声传感器配置在一个环形山边缘站上方的垂直线上，将首次使我们能够调查次声源的准确垂直位置。最后，我们将创建一个原型并测试无人机次声传感器部署，在该部署中，传感器被飞行到无法到达的区域，由无人机放下并取回。这项技术可用于未来火山喷发危机期间的监测。作为该项目更广泛影响的一部分，耶兹博士将教授一门阅读研讨会课程，并设计一个模仿无人机在亚苏尔火山周围使用的演示，名为“垃圾”，肯定会引起中学生的兴趣。外展活动包括一本来自亚苏尔火山的照片日记，与当地教师分享，从而扩大外展教育工作。这一奖项反映了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。

Dr. Alexandra Iezzi has been granted an NSF EAR Postdoctoral Fellowship to carry out research and educational activities at the University of California Santa Barbara under the mentorship of Professor Robin Matoza. Infrasound sensors measure low-frequency acoustic waves (below the limit of human hearing) and provide a detailed means to monitor and characterize explosive sources such as those caused by volcanic eruptions. However, these sensors are usually placed on the Earth's surface, providing only a limited sampling of the acoustic radiation pattern and directionality of volcanic explosions creating a bias in how acoustic sources are characterized. This project addresses this issue by using a novel approach of collecting infrasound data with sensors aboard multiple unmanned aerial vehicles (UAVs) in addition to traditional sensor deployments on the ground. Our sensor platform and measurements will increase our understanding of acoustic directivity at the frequently active Yasur volcano, in Vanuatu and for explosive sources in general. The research proposed here has the potential to revolutionize the way active volcanoes are monitored using infrasound instrumentation aimed at providing unique information on explosion dynamics. The new techniques proposed will allow infrasound sensors to be deployed both in the air and on the ground close to the eruption, so that a volcanic source is understood better with significantly reduced risk exposure to field personnel. This project is a proof-of-concept study of UAV-based infrasound deployments that can extend data collection to previously unreachable locations near active volcanoes and anthropogenic explosion sources around the world. The UAV-mounted infrasound sensors will record data from unique angles, allowing for acoustic source inversion methods that account for the effects of topography to constrain the directional radiation pattern of explosions in a way not previously possible. By following these methods, we will also improve the calculation of the mass flow rate, which is an invaluable parameter for monitoring. The infrasound observations will be validated with ballistic trajectories determined from multiple cameras deployed around the crater rim, which we assume to be similar to the directionality of ash, gas, and steam emissions that may present harm to those near the volcano. Configuring UAV-mounted infrasound sensors in a vertical line above one of the crater rim stations will, for the first time, allow us to investigate the precise vertical location of the infrasonic source. Finally, we will create a prototype and test a UAV infrasound sensor deployment where the sensor is flown to an inaccessible area, dropped off, and retrieved by the UAV. This technique can be applied for future monitoring during times of eruption crises. As part of the broader impacts of this project Dr. Iezzi will teach a reading seminar course and design a demonstration mimicking the usage of UAVs around Yasur volcano entitled “trashcano”, which is sure to catch middle-school students’ interest. Outreach activities include a photo-journal from Yasur volcano to share with local teachers and thus expanding outreach educational efforts.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.