SeisMic Observations of deep VolcAnic pRocesses

我们的目标是研究喷发前的过程中，在俯冲带火山的管道系统的深层部分的地震观测的基础上。火山是由地幔中产生的熔融物供给的，这些熔融物通过一个复杂而难以捉摸的管道系统上升到地表，该系统结合了无处不在的集中流动和多级水库。火山-岩浆系统中的过程可以根据其地震学表现来研究。由岩浆和气体输送引起的压力变化会产生特定的地震信号，以及周围岩石中的应力变化，从而导致其弹性特性的变化。最大和最危险的爆炸性火山爆发是从几公里深的岩浆储层中提供的。目前，大多数地震观测反映了浅火山爆发前的活动。与此同时，要充分了解火山系统的运作和发现火山重新活动的最早迹象，就需要观察火山深处的过程。为此，我们将研究堪察加半岛的克柳切夫斯基火山群（KVG），这是世界上最大和最活跃的俯冲火山群，其特征是深部地震火山活动的系统发生。拟议的研究将基于两个主要数据集的分析，这两个数据集完全互补。首先，我们将使用2015-2016年80多台宽带地震仪在KVG地区运行时的大型德法俄联合野外实验KISS的数据（Shapiro et al.，2017年a），并记录了2016年克柳切夫斯基火山爆发，包括前所未有的空间覆盖范围的准备阶段。我们将把它与我们的俄罗斯合作伙伴在KVG上运行的永久地震网络的长期记录（部分超过20年）结合起来，该网络目前由25个台站组成。该数据集包含三个主要KVG火山的30多个强烈喷发（VEI高达4）的记录：Klyuchevskoy，Bezymiammy和Tolbachik，其中大多数都是在深地震火山活动之前。我们将使用现代地震学方法分析可用数据，包括基于时间推移噪声和地震的监测，以及随时间变化的地震各向异性测量。这些调查的结果将反映管道系统的活动及其对地壳机械性质的影响。它们将被用来限制和量化的基础上的物理过程的地球物理流体动力学模型的粘性流在多孔介质中分析我们的合作者。作为主要的科学成果，我们预计将建立一个控制岩浆从岩浆系统深部向地表上升的过程的综合物理模型，并建立一套可用于监测这些深层喷发前过程的地震学方法。

We aim to study pre-eruptive processes in the deep parts of plumbing systems in subduction zone volcanoes based on seismological observations. Volcanoes are fed by melts that are generated in the mantle and ascend to the surface through a complex and elusive plumbing system that combines pervasive and focused flows and multi-level reservoirs. The processes in the volcano-magmatic systems can be studied based on their seismological manifestations. Pressure variations caused by magma and gas transport generate specific seismic signals as well as stress variations in the surrounding rock that result in variations of its elastic properties.Largest and most dangerous explosive volcanic eruptions are fed from a few kilometers deep magmatic reservoirs. Currently, most seismological observations reflect the shallow pre-eruptive activity. At the same time fully understanding the functioning of volcanic systems and detecting earliest signs of volcanic re-activation requires observations of the processes in the deep volcanic roots. For this purpose, we will study the Klyuchevskoy Volcanic Group (KVG) in Kamchatka that is the largest and the most active cluster of subduction volcanoes in the world and features the systematic occurrence of deep seismo-volcanic activity.The proposed research will be based on the analysis of two major datasets that perfectly complement each other. First, we will use the data of a large joint German-French-Russian field experiment KISS when more than 80 broadband seismographs operated in the KVG region in 2015-2016 (Shapiro et al., 2017a) and recorded the 2016 Klyuchevskoy eruption including the preparatory phase with unprecedented spatial coverage. We will combine this with the long-term records (partly > 20 years) of the permanent seismic network operated on KVG by our Russian partners, composed today of 25 stations. This dataset contains records of more than 30 strong eruptions (VEI up to 4) of the three major KVG volcanoes: Klyuchevskoy, Bezymiammy, and Tolbachik with most of them being preceded by the deep seismo-volcanic activity.We will analyze the available data with modern seismological methods including time-lapse noise- and earthquake-based monitoring, and measurements of time-variable seismic anisotropy. The results of these investigations will reflect the activity in the plumbing system and its influence on the mechanical properties of the crust. They will be used to constrain and quantify the underlying physical processes based on geophysical fluid dynamics models of viscous flow in porous media analysed by our collaborators. As main scientific results, we anticipate developing a comprehensive physical model of the processes controlling the magma ascent from the deep parts of magmatic systems towards the surface and a set of seismological methods that can be used to monitor these deep-seated pre-eruptive processes.