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Stress fields around magma chambers influenced by elastic thermo-mechanical deformation: implications for forecasting chamber failure
Bulletin of Volcanology ( IF 3.6 ) Pub Date : 2021-07-01 , DOI: 10.1007/s00445-021-01471-2
J. Browning , Ö. Karaoğlu , Ö. Bayer , M. B. Turgay , V. Acocella

Defining the conditions that lead to the rupture of a magma chamber is essential to forecast eruptions. So far, models simulating magma chamber dynamics have neglected the effects of elastic thermal expansion in the host rocks surrounding a new injection of magma, focusing instead primarily on elastic-plastic deformation and more recently, on visco-elastic deformation. Here we fill this gap by building a suite of elastic thermo-mechanical models to determine the stress field around a variably heated crustal magma chamber. We first consider linear elastic mechanical models with only the effect of magma pressure. We then present purely thermal models simulating heat distribution around a heated chamber. Finally, we present coupled linear elastic thermo-mechanical models that highlight the influence of temperature on the distribution of crustal stresses. Results show that thermal expansion–induced stresses generate two competing consequences: (1) they increase the level of shear stress around the magma chamber and (2) they partially suppress the level of tensile stress generated by the magmatic pressure. These competing effects influence the short-timescale conditions required for the failure of immature magmatic systems and hence the nucleation of dikes which may ultimately feed eruptions during unrest. Therefore, soon after a new magmatic recharge event, the contribution of temperature increase in the host rocks, following the new influx of magma into a crustal magma chamber, should be considered.



中文翻译:

受弹性热机械变形影响的岩浆室周围的应力场:对预测室失效的影响

确定导致岩浆房破裂的条件对于预测喷发至关重要。到目前为止,模拟岩浆房动力学的模型忽略了围绕新注入岩浆的主岩中弹性热膨胀的影响,而主要关注弹塑性变形,最近则关注粘弹性变形。在这里,我们通过建立一套弹性热机械模型来确定可变加热地壳岩浆房周围的应力场来填补这一空白。我们首先考虑仅具有岩浆压力影响的线弹性力学模型。然后,我们展示了模拟加热室周围热量分布的纯热模型。最后,我们提出了耦合线弹性热机械模型,强调了温度对地应力分布的影响。结果表明,热膨胀引起的应力会产生两种相互竞争的结果:(1)它们增加了岩浆房周围的剪切应力水平;(2)它们部分抑制了岩浆压力产生的拉伸应力水平。这些相互竞争的影响会影响未成熟岩浆系统失效所需的短时间尺度条件,从而影响岩脉的成核,最终可能会在动乱期间引发火山喷发。因此,在新的岩浆补给事件发生后不久,应考虑随着新的岩浆流入地壳岩浆房,主岩温度升高的贡献。结果表明,热膨胀引起的应力会产生两种相互竞争的结果:(1)它们增加了岩浆房周围的剪切应力水平;(2)它们部分抑制了岩浆压力产生的拉伸应力水平。这些相互竞争的效应会影响未成熟岩浆系统失效所需的短时间尺度条件,从而影响岩脉的成核,最终可能在动乱期间引发火山喷发。因此,在新的岩浆补给事件发生后不久,应考虑随着新的岩浆流入地壳岩浆房,主岩温度升高的贡献。结果表明,热膨胀引起的应力会产生两种相互竞争的结果:(1)它们增加了岩浆房周围的剪切应力水平;(2)它们部分抑制了岩浆压力产生的拉伸应力水平。这些相互竞争的效应会影响未成熟岩浆系统失效所需的短时间尺度条件,从而影响岩脉的成核,最终可能在动乱期间引发火山喷发。因此,在新的岩浆补给事件发生后不久,应考虑随着新的岩浆流入地壳岩浆房,主岩温度升高的贡献。这些相互竞争的影响会影响未成熟岩浆系统失效所需的短时间尺度条件,从而影响岩脉的成核,最终可能会在动乱期间引发火山喷发。因此,在新的岩浆补给事件发生后不久,应考虑随着新的岩浆流入地壳岩浆房,主岩温度升高的贡献。这些相互竞争的影响会影响未成熟岩浆系统失效所需的短时间尺度条件,从而影响岩脉的成核,最终可能会在动乱期间引发火山喷发。因此,在新的岩浆补给事件发生后不久,应考虑随着新的岩浆流入地壳岩浆房,主岩温度升高的贡献。

更新日期:2021-07-02
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