Previous studies of the major eruption at Shinmoe-dake volcano, Japan, in January 2011 suggested that gradual injection of magma from a deep source into a shallow reservoir began in December 2009 and led to the major eruption. To investigate the initial phase of this injection event, we examined extensometer data from the Isa Observatory, ~ 18.5 km from the summit of Shinmoe-dake, and discovered a strain change event that spanned about 3 days in December 2009. The size of the strain change is comparable to those observed during each sub-Plinian eruption in 2011. The source of the rapid strain change appears to be deeper than the estimated location of the magma reservoir that directly supplied magma to the 2011 eruption sequence. These observations suggest that rapid injection of magma from the deep magmatic plumbing system in December 2009 triggered the continuous ascent of additional magma from depth, which in turn drove the climactic eruptions in January 2011. Extensometers also recorded two rapid strain change events of the same order of magnitude and with similar characteristics in December 2006 and August 2008; however, noticeable inflation of the edifice was not detected immediately following either event. This suggests that transient injection of magma into a shallow reservoir is not always followed immediately by a gradual recharge process.

中文翻译：

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在与 2011 年日本 Shinmoe-dake 喷发相关的前兆岩浆储层膨胀之前，安装在拱顶上的引伸计记录了一个快速的初始脉冲

先前对 2011 年 1 月日本新萌岳火山大喷发的研究表明，2009 年 12 月，岩浆从深源逐渐注入浅水库，导致了大喷发。为了研究这次注入事件的初始阶段，我们检查了距离 Shinmoe-dake 山顶约 18.5 公里的 Isa 天文台的引伸计数据，并发现了 2009 年 12 月持续约 3 天的应变变化事件。应变的大小变化与 2011 年每次亚普林尼亚喷发期间观察到的变化相当。快速应变变化的来源似乎比估计的岩浆库位置更深，该岩浆库直接为 2011 年喷发序列提供岩浆。这些观察结果表明，2009 年 12 月深部岩浆管道系统的岩浆快速注入引发了额外岩浆从深处不断上升，进而推动了 2011 年 1 月的高潮喷发。引伸计还记录了两次相同数量级的快速应变变化事件2006 年 12 月和 2008 年 8 月的规模和特征相似；然而，在任何一个事件发生后，都没有立即检测到建筑物的明显膨胀。这表明岩浆瞬时注入浅层储层并不总是紧随其后的是逐渐补给过程。引伸计还在 2006 年 12 月和 2008 年 8 月记录了两个具有相同数量级和相似特征的快速应变变化事件；然而，在任何一个事件发生后，都没有立即检测到建筑物的明显膨胀。这表明岩浆瞬时注入浅层储层并不总是紧随其后的是逐渐补给过程。引伸计还在 2006 年 12 月和 2008 年 8 月记录了两个具有相同数量级和相似特征的快速应变变化事件；然而，在任何一个事件发生后，都没有立即检测到建筑物的明显膨胀。这表明岩浆瞬时注入浅层储层并不总是紧随其后的是逐渐补给过程。