Volcanic inflation measured in the caldera of Axial Seamount: Implications for magma supply and future eruptions
Volcanic inflation measured in the caldera of Axial Seamount: Implications for magma supply and future eruptions
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在轴海山火山口测量的火山膨胀：对岩浆供应和未来喷发的影响
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
W. Chadwick
中科院分区：
文献类型：
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作者：
S. Nooner;W. Chadwick
自2000年以来，在Axial Semount的顶峰破火山口内的五个海底基准上精确测量了周围的海水压力，以监测火山通货膨胀，在运动式调查中使用遥控工具部署了移动压力记录器。此外，已经在火山口中心测量了海水压力，并部署了多年的连续记录海底压力记录器(BPR)。这些压力数据(转换为深度)是目前唯一测量海底火山火山膨胀的数据。我们展示了从2004年到2007年的新数据，记录了火山口中心12.7±0.4厘米/年的稳定通货膨胀。上升的空间模式与∼3.5kM深的破火山口下浅层储集层中的岩浆储存相一致，目前的上升速率意味着岩浆正以∼7.5×106m~3/a的速度供应给火山。然而，1998年最后一次喷发后的供应速率明显更高，轴向破火山口的上升的时间模式似乎至少受两个不同时间尺度上发生的过程控制。我们将1998年喷发后的高隆升速率解释为要么是一个或多个小型卫星岩浆体涌入的结果，要么是浅层岩浆室周围地壳的粘弹性松弛和/或孔弹行为的结果，我们给出了一个支持后一种解释的数值模型。相反，我们将目前较低的抬升速率解释为地幔长期稳定的岩浆供应。在陆地火山上没有观察到这种双分量隆升模式，这表明该脊轴火山之下的岩浆供应/储存过程不同于陆地火山(包括冰岛)。为了重建Axial的隆升历史，我们将MPR和BPR的组合数据与两种可能的隆升情景进行了拟合，我们预测Axial的下一次火山喷发可能在2020年左右发生，届时1998年喷发期间发生的∼3m的大部分通货紧缩将被恢复。
Since 2000, ambient seawater pressure has been precisely measured at five seafloor benchmarks inside the summit caldera at Axial Seamount to monitor volcanic inflation, using a remotely operated vehicle to deploy a mobile pressure recorder (MPR) in campaign‐style surveys. Additionally, seawater pressure has been measured at the caldera center with multiyear deployments of continuously recording bottom pressure recorders (BPRs). These pressure data (converted to depth) are currently the only measurements of volcanic inflation at a submarine volcano. We show new data spanning 2004 to 2007 documenting steady inflation of 12.7 ± 0.4 cm/a at the caldera center. The spatial pattern of uplift is consistent with magma storage in a shallow reservoir underlying the caldera at a depth of ∼3.5 km, and the current uplift rate implies that magma is being supplied to the volcano at a rate of ∼7.5 × 106 m3/a. However, the supply rate immediately after the last eruption in 1998 was significantly higher, and the temporal pattern of uplift at Axial caldera appears to be governed by at least two processes occurring at very different time scales. We interpret the high uplift rates immediately following the 1998 eruption as either due to influx from one or more small satellite magma bodies or as the result of viscoelastic relaxation and/or poroelastic behavior of the crust surrounding the shallow magma chamber, and we present a numerical model which supports the latter interpretation. In contrast, we interpret the current lower uplift rate as due to a steady longterm magma supply from the mantle. This two component uplift pattern has not been observed on land volcanoes, suggesting that magma supply/storage processes beneath this ridge axis volcano differ from volcanoes on land (including Iceland). To reconstruct the uplift history at Axial, we fit the combined MPR and BPR data to two possible uplift scenarios, with which we forecast that the next eruption at Axial is likely to occur by about 2020, when most of the ∼3 m of deflation that occurred during the 1998 eruption will have been recovered.
影响因子：
2.8
作者：
Ebinger, C. J.;Keir, D.;Buck, W. R.
通讯作者：
Buck, W. R.