Three Compliance Instruments for Axial Volcano to Observe Long Term Evolution of the Magma Chamber and in Support of OOI Observations

尽管有几十年的观测，岩浆如何迁移和储存在火山内仍然知之甚少，因为几乎没有方法连续监测火山下岩浆库的变化。需要进行这样的测量，以了解岩浆逐渐就位最终何时以及如何引发喷发。 开发的仪器将提供连续监测海底火山下方岩浆含量变化的潜力，从而更好地了解火山过程，这些过程也可应用于对数百万人构成重大危险的陆地火山。轴向火山，一个大型的，美国西海岸近海的一座非常活跃的海底火山目前正在使用传感器进行监测，这些传感器通过NSF支持的海洋观测站传输数据主动电缆到海岸。 这些电缆上的传感器测量了2015年火山爆发前后与岩浆房变化相关的海底顺应性变化，但这些传感器的噪声水平限制了观测的灵敏度，并将观测期限制在顺应性信号较大的冬季月份。灵敏度更高、噪音水平更低的新的顺应性传感器将使用更优化的传感器建造，并放置在海底的大型屏蔽下，保护传感器免受洋流噪音的影响。柔度是对海底在长周期海浪载荷下变形的一种度量，它取决于下伏地球的弹性特性，从而取决于岩浆房中岩浆的比例。所开发的电流屏蔽还将适用于降低安装在海底的宽带地震仪水平部件的噪声水平。海底地震仪对于了解许多地球过程至关重要，但由于海底洋流造成的高噪声水平限制了观测的类型和质量。该奖项反映了NSF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。

Despite decades of observations, how magma migrates and is stored within volcanoes remains poorly understood because there are few means to continuously monitor changes within magma chambers beneath volcanoes. Such measurements are needed to understand when and how the gradual emplacement of magma finally triggers an eruption. The instrumentation developed will provide the potential to monitor changes in the magma content continuously beneath undersea volcanoes and thereby provide a better understanding of volcano processes that can also be applied to volcanos on land that pose a major hazard to millions of people.Axial Volcano, a large, very active undersea volcano offshore the US West Coast is currently monitored using sensors that transmit data through the NSF supported Ocean Observatories Initiative cable to shore. Sensors on these cables measured changes in the compliance of seafloor preceding and following an eruption in 2015 associated with changes in the magma chamber, but the noise level of these sensors limited the sensitivity of the observations and the observation period to the winter months when the compliance signal was larger. New compliance sensors with better sensitivity and a lower noise level will be constructed using more optimal sensors and placed on the seafloor beneath large shields that protect the sensors from noise from ocean currents. Compliance, a measure the deformation of the seafloor under the loading of long period ocean waves, depends on the elastic properties of the underlying Earth and thereby to the fraction of magma within the magma chamber. The current shielding developed will also have applicability for reducing the noise levels for the horizontal components of broadband seismometers installed on the seafloor. Ocean bottom seismometers are critical to understanding many Earth processes, but the high noise levels due to ocean floor currents limits the types and quality of observations that can be made.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.