Collaborative Research: Advancing Deformation Monitoring Methods at Axial Seamount

该研究项目继续对世界上最活跃的海底火山进行长期研究和监测。轴向海山位于俄勒冈州海岸外约300英里处，是研究火山如何工作的最佳地点之一，因为它经常重复喷发，并且有许多监测仪器通过电缆与海岸相连，这是新委托的国家科学基金会海洋观测计划的一部分。这项研究的重点是继续目前的时间序列数据收集工作，并利用这些数据来了解岩浆（熔融岩石）如何储存在火山的浅层地壳中，它如何被输送到地表，如何触发火山爆发，以及如何成功地预测火山爆发。现场工作包括使用新开发的精密压力传感器和自动水下航行器，使用大地测量学来测量海底的垂直运动，这种运动发生在轴向海山像气球一样逐渐膨胀时，岩浆渗入并填满海底以下几公里处的地下岩浆室。在通货膨胀（目前的情况）和通货紧缩（由于海底熔岩喷发造成的体积损失，最后一次发生在2015年）期间，海底上下移动多达8-12英尺。根据阿克塞勒火山最近两次喷发周期的观察，当火山完全“重新膨胀”时，它就准备好再次喷发了。近二十年的监测表明，轴向海山在每次喷发前都会膨胀到相似的程度。这使得前两次喷发能够提前几个月成功预测。收集这些新数据将辅以地球动力学建模，重点是了解火山膨胀如何影响周围的变形场。这项研究的广泛影响对火山危害的理解有广泛的影响，利用新的海洋观测倡议的电缆阵列和补充传感器套件，帮助建立科学基础设施，并为学生提供培训。它还将产生一个新的软件包，使自主水下航行器能够在海底执行地形跟踪网格。这项研究的结果可能对更好地理解陆地上与火山有关的岩浆库填充和喷发具有重要意义，因为大陆地壳常常增加了基性岩浆生成和岩浆库填充过程的复杂性。轴形海山位于美国西北海岸外的胡安·德·富卡山脊上。它分别在1998年和2011年爆发，最近一次是在2015年4月。在这段时间里，它已经配备了传感器，可以探测到地面运动和海拔随时间的变化。它现在被连接到海底数据电缆和国家科学基金会海洋观测倡议电缆阵列的接线盒上。因此，轴向海山是长期研究洋中脊海底火山活动过程的理想天然实验室。对轴向火山的长期研究和监测已经创建了一个了不起的底部压力观测时间序列数据集，揭示了通货膨胀和通货紧缩的重复周期，用于预测火山爆发的准确性越来越高。2015年的喷发是第一次被安装在火山口及其侧面的传感器网络实时捕捉到。这些装置以前所未有的细节揭示了火山的内部运作。这项研究将在最近的工作基础上继续进行，使用自主水下航行器生成高分辨率的水深图，显示轴向变形场远远超出其山顶破火山口。这些新数据补充了连续但空间有限的压力传感器测量结果，并将其纳入地质、形态框架。该研究将继续进行压力测量，并进一步开发一种新的自主水下航行器导航技术，以提高海底测量的可靠性和可重复性。这一结果将用于推进轴向地下岩浆系统变形的建模。它还将探索新的定量数值方法来改进火山喷发预报。

This research project continues long-term study and monitoring of the most active submarine volcano in the world. Axial Seamount is located about 300 miles off the coast of Oregon and represents one of the best places to study how volcanoes work because it erupts frequently and repetitively and has numerous monitoring instruments linked to shore via cable which is part of the newly commissioned National Science Foundation's Ocean Observing Initiative. This research focuses on continuing the present time series data collection effort and using the data to understand how magma (molten rock) is stored in the shallow crust at volcanoes, how it is delivered to the surface, how eruptions are triggered, and how eruptions can be successfully forecast. Field work involves use of newly developed, precise, pressure sensors and autonomous underwater vehicles using geodetics to measure vertical movements of the seafloor, which take place as Axial Seamount, gradually inflates like a balloon, with magma seeping in and filling its subterranean magma chamber a few kilometers below the seafloor. During inflation (the present situation) and deflation (loss of volume due to eruption of lavas on the seafloor, the last of which occurred in 2015) the seafloor moves up and down as much as 8-12 feet. As observed in Axial's last two eruption cycles, when the volcano is fully "re-inflated" it is ready to erupt again. Monitoring for almost two decades has shown that Axial Seamount inflates to a similar amount before each eruption. This allowed the two previous eruptions to be successfully forecast months in advance. Collection of this new data will be complemented by geodynamic modeling focused on understanding how volcano inflation influences the deformation field around it. Broader impacts of this research have broad implications for the understanding of volcano hazards, utilizes the new Ocean Observing Initiative's cabled array and complementary sensor suites, helps build infrastructure for science, and provides training for students. It will also result in a new software package to enable autonomous underwater vehicles to perform terrain-following grids of features on the seafloor. Results from this study may have important implications for better understanding magma chamber filling and eruption associated with volcanoes on land where the continental crust, many times, adds complexity to fundamental magma generation and magma chamber filling processes.Axial Seamount is on the Juan de Fuca Ridge off the coast of the northwestern United States. It erupted in 1998, 2011, and most recently again in April 2015. It has been instrumented for this period of time with sensors that can detect ground motion and changes in elevation over time. It is now hooked to the undersea data cable and junction box of the National Science Foundation's Ocean Observing Initiative's cabled array. Thus, Axial Seamount is an ideal natural laboratory for the long-term study of active processes of submarine volcanos in a mid-ocean ridge setting. Long-term research and monitoring of Axial has created a remarkable time-series dataset of bottom pressure observations that have revealed repeated cycles of inflation and deflation that have been used to forecast eruptions with increasing accuracy. The 2015 eruption was the first captured in real time by the network of sensors now installed inside the volcano's caldera and on its flanks. These installations have revealed the inner workings of the volcano in unprecedented detail. This research will follow up on recent work by using autonomous underwater vehicles that generate high-resolution bathymetric maps that show the Axial deformation field extends well beyond its summit caldera. These new data complement the continuous, but spatially limited, pressure sensor measurements and put them into a geologic, morphological framework. This research will continue the pressure measurements and further develop a new autonomous underwater vehicle navigation technique to improve seafloor survey reliability and reproducibility. Results of this will be used to advance modeling of the deformation of the Axial subsurface magmatic system. It will also explore new quantitative numerical methods for improving eruption forecasts.