Wavelet-Based Characterization of Very-Long-Period Seismicity Reveals Temporal Evolution of Shallow Magma System Over the 2008-2018 Eruption of Kilauea Volcano
Wavelet-Based Characterization of Very-Long-Period Seismicity Reveals Temporal Evolution of Shallow Magma System Over the 2008-2018 Eruption of Kilauea Volcano
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DOI：
10.1029/2020jb020837
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发表时间：
2021-06-01
影响因子：
3.9
通讯作者：
Karlstrom, Leif
中科院分区：
文献类型：
--
作者：
Crozier, Josh;Karlstrom, Leif
甚长周期(VLP)火山地震活动往往编码了地下岩浆运动，从而提供了对地下岩浆运输过程的洞察。我们开发了一种使用小波变换的全自动信号处理流程来检测和评估共振VLP信号的周期、衰减率和地面运动。然后，我们生成一份关于2008-2018年基拉韦厄火山开放喷口峰会喷发的VLP目录，其中包含数千项事件。我们的目录中主要有两种类型的岩浆共振：浅层岩浆储集层内外开放岩浆柱的垂直晃动和熔岩湖中岩浆的横向晃动。这些事件主要是从表层触发的，较少从深处触发。然后，将VLP目录与其他地球物理数据集结合起来，以表征浅层岩浆系统的演化。VLP地面运动模式显示了浅层岩浆储集层几何形状的突变和渐变。两种共振类型的共振周期和衰减率的变化在从几个小时到几年的时间尺度上发生，表明岩浆密度和粘度的变化可能反映了不稳定的浅层放气和对流。两个主要共振模式的衰减率之间缺乏相关性，这表明导管和熔岩湖中的岩浆之间存在解耦。已知的侵入和裂谷带喷发往往代表着共振特征及其与其他数据集的关系的变化点。基拉韦厄火山10年喷发事件的数据综合表明，VLP地震活动可以加深对岩浆系统演化的洞察，用于监测和了解喷发过程。
Very-long-period (VLP) volcano seismicity often encodes subsurface magma movement, and thus provides insight into subsurface magma transport processes. We develop a fully automated signal processing workflow using wavelet transforms to detect and assess period, decay rate, and ground motions of resonant VLP signals. We then generate a VLP catalog over the 2008-2018 open-vent summit eruption of Kilauea Volcano containing thousands of events. Two types of magma resonance dominate our catalog: vertical sloshing of the open magma column in and out of the shallow magma reservoir, and lateral sloshing of magma in the lava lake. These events were triggered mainly from the surface and less commonly from depth. The VLP catalog is then combined with other geophysical datasets to characterize evolution of the shallow magma system. VLP ground motion patterns show both abrupt and gradual changes in shallow magma reservoir geometry. Variation in resonant periods and decay rates of both resonance types occurred on timescales from hours to years, indicating variation in magma density and viscosity that likely reflect unsteady shallow outgassing and convection. A lack of correlation between decay rates of the two dominant resonant modes suggests a decoupling between magma in the conduit and lava lake. Known intrusions and rift zone eruptions often represented change points for resonance characteristics and their relations with other datasets. This data synthesis over a 10-year eruptive episode at Kilauea Volcano demonstrates how VLP seismicity can sharpen insights into magma system evolution for use in monitoring and understanding eruptive processes.