A magma plumbing system with dual magma chambers beneath active volcanoes is commonly observed through petrological and geophysical measurements. This paper developed a physical model for the dynamics of a dual-magma-chamber system during volcanic eruptions. The model consists of the plumbing system where two elastically deformable magma chambers are connected in series with non-deformable conduits. Based on this model, we obtained an analytical solution that describes temporal changes in pressures at the two chambers accompanied by the eruption. The analytical solution showed that the feature of the chamber pressure changes is mainly controlled by two non-dimensional numbers \(C'\) and \(\Omega '\). Here, \(C'\) is the ratio of the parameter controlling the magnitude of pressure change in the shallower chamber to that in the deeper chamber, and \(\Omega '\) is the ratio of conduit’s conductivity (inverse of resistivity to magma flow) between the shallower chamber and the surface to that between the chambers. For smaller \(C'\) and \(\Omega '\), the shallower chamber’s pressure is kept constant during the decrease in the pressure at the deeper chamber in the initial phase of the eruption. This corresponds to a deformation pattern commonly observed in some eruptions, in which the deflation of the deeper chamber was predominant. The estimation of \(C'\) and \(\Omega '\) based on the parameters related to magma properties and geometries of the chambers and the conduits revealed that the smaller \(C'\) and \(\Omega '\) conditions are satisfied under realistic magmatic and geological parameters. This indicates that the magma dynamics in the dual-chamber system generally cause the dominance of the deeper chamber’s deflation.

通常通过岩石学和地球物理测量可以观察到活火山下面具有双岩浆室的岩浆管道系统。本文为火山爆发期间双岩浆腔系统的动力学建立了物理模型。该模型由管道系统组成，其中两个可弹性变形的岩浆室与不可变形的管道串联连接。基于此模型，我们获得了一个解析解决方案，该解决方案描述了伴随喷发的两个腔室中压力的时间变化。解析解表明，腔室压力变化的特征主要受两个无量纲数\（C'\）和\（\ Omega'\）的控制。在这里，\（C'\）是控制较浅腔室与较深腔室中压力变化幅度的参数之比，\（\ Omega'\）是较浅腔室与较深腔室之间的导管电导率（电阻率与岩浆流动量的倒数）之比。腔室之间的表面。对于较小的\（C'\）和\（\ Omega'\），在喷发初始阶段，较深腔室的压力下降期间，较浅腔室的压力保持恒定。这对应于在某些喷发中通常观察到的变形模式，其中较深腔室的放气是主要的。\（C'\）和\（\ Omega'\）的估计基于与岩浆特性和腔室和导管的几何形状有关的参数，揭示了在实际的岩浆和地质参数下满足较小的\（C'\）和\（\ Omega'\）条件。这表明，双室系统中的岩浆动力学通常会引起深室放气的主导。