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首页> 外文期刊>Geochemistry, geophysics, geosystems >Imaging the magmatic system of Newberry Volcano using Joint active source and teleseismic tomography
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Imaging the magmatic system of Newberry Volcano using Joint active source and teleseismic tomography

机译：使用联合有源源和远震层析成像技术对纽伯里火山的岩浆系统进行成像

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摘要

In this paper, we combine active and passive source P wave seismic data to tomographically image the magmatic system beneath Newberry Volcano, located east of the Cascade arc. By using both travel times from local active sources and delay times from teleseismic earthquakes recorded on closely spaced seismometers (300-800 m), we significantly improve recovery of upper crustal velocity structure (<10 km depth). The tomographic model reveals a low-velocity feature between 3 and 5 km depth that lies beneath the caldera, consistent with a magma body. In contrast to earlier tomographic studies, where elevated temperatures were sufficient to explain the recovered low velocities, the larger amplitude low-velocity anomalies in our joint tomography model require low degrees of partial melt (approximate to 10%), and a minimum melt volume of approximate to 2.5 km(3). Furthermore, synthetic tests suggest that even greater magnitude low-velocity anomalies, and by inference larger volumes of magma (up to 8 km(3)), are needed to explain the observed waveform variability. The lateral extent and shape of the inferred magma body indicates that the extensional tectonic regime at Newberry influences the emplacement of magmatic intrusions. Our study shows that jointly inverting active source and passive source seismic data improves tomographic imaging of the shallow crustal seismic structure of volcanic systems and that active source experiments would benefit from longer deployment times to also record teleseismic sources.
机译：在本文中，我们结合了主动和被动源P波地震数据，以断层成像方式对位于Cascade弧以东的Newberry火山下面的岩浆系统成像。通过同时使用本地活动源的传播时间和近距离地震仪（300-800 m）记录的远震地震的延迟时间，我们显着提高了上地壳速度结构（<10 km深度）的恢复。层析成像模型揭示了位于火山口下方3至5公里深度之间的低速特征，与岩浆体一致。与早期的层析成像研究相反，在高温下的层析成像研究足以说明已恢复的低速度，而在我们的联合层析成像模型中，较大幅度的低速度异常需要较低程度的部分熔融（约10％），并且最小熔融量为约2.5公里（3）。此外，综合测试表明，需要更大的低速异常，并通过推断更大的岩浆量（最大8 km（3））来解释观测到的波形变化。推断岩浆体的横向范围和形状表明，纽伯利的伸展构造机制影响着岩浆侵入的位置。我们的研究表明，将主动震源和被动震源数据联合反演可以改善火山系统浅层地壳地震结构的层析成像，而主动震源实验将受益于更长的部署时间来记录远震震源。

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