Marapi in Sumatra is characterized by frequent short‐lived explosions and small eruptions (Volcanic Explosivity Index 1–2) and in the past 250 years, the volcano has erupted >60 times. Recent volcanic bombs and the presence of broadband seismic stations lead us to reconstruct the plumbing system of the volcano through an interdisciplinary study. A petrologic study of the summit bombs uses pyroxene, plagioclase and glass compositions to obtain pressures and temperatures of magma storage as well as identify pre‐eruptive processes. Two‐pyroxene geothermobarometry provides pre‐eruptive crystallization pressure estimates of 4–7 kbar (∼15–26 km). Compositional and textural analyses of plagioclase and pyroxene crystals indicate that mafic magma recharge was followed by mixing with the resident magma and renewed crystallization prior to eruption. In order to further image the magma reservoir, we performed a joint inversion of teleseismic receiver functions and surface waves (H/V ratio). The inversion reveals a low velocity zone (LVZ) at depths of 15–21 km that has 7 ± 3% shear velocity reduction, corresponding to an estimated melt fraction of 5 ± 2%. The depth of this LVZ overlaps with the depth of magma storage estimated from petrology, constraining it with high confidence. Such a combined interdisciplinary study provides valuable information for evaluating future periods of unrest, laying out a framework for the interpretation of incoming monitoring data and signals to look out for in order to improve eruption forecasts.

中文翻译：

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结合岩石学和地震学来揭示典型弧形火山的管道系统：以印度尼西亚西苏门答腊省的马拉皮为例

苏门答腊岛的玛拉皮岛（Marapi）的特点是频繁发生的短暂爆炸和小喷发（火山爆发指数1-2），并且在过去250年中，该火山喷发了60多次。最近的火山炸弹和宽带地震台的存在使我们通过跨学科研究来重建火山的管道系统。对山顶炸弹的岩石学研究使用辉石，斜长石和玻璃成分来获得岩浆储存的压力和温度，并确定喷发前的过程。两吡geo地热气压法提供的术前结晶压力估计为4-7 kbar（约15-26 km）。斜长石和辉石晶体的组成和结构分析表明，镁铁质岩浆充注后与常驻岩浆混合，并在喷发前重新结晶。为了进一步对岩浆储层进行成像，我们对远震接收器函数和表面波（高/垂直比）进行了联合反演。反演结果表明，在15–21 km的深度处有一个低速带（LVZ），其剪切速度降​​低了7±3％，相当于估计的熔体分数为5±2％。LVZ的深度与岩石学估计的岩浆储藏深度重叠，从而高置信度对其进行了约束。这样的跨学科研究为评估未来动乱提供了有价值的信息，为解释即将到来的监测数据和信号提供了解释框架，以改善喷发预报。反演结果表明，在15–21 km的深度处有一个低速带（LVZ），其剪切速度降​​低了7±3％，相当于估计的熔体分数为5±2％。LVZ的深度与岩石学估计的岩浆储藏深度重叠，从而高置信度对其进行了约束。这样的跨学科研究为评估未来动乱提供了有价值的信息，为解释即将到来的监测数据和信号提供了解释框架，以改善喷发预报。反演结果表明，在15–21 km的深度处有一个低速带（LVZ），其剪切速度降​​低了7±3％，相当于估计的熔体分数为5±2％。LVZ的深度与岩石学估计的岩浆储藏深度重叠，从而高置信度对其进行了约束。这样的跨学科研究为评估未来动乱提供了有价值的信息，为解释即将到来的监测数据和信号提供了解释框架，以改善喷发预报。