Rhodes Emma, Burchardt Steffi, Greiner Sonja H M, Mattsson Tobias, Sigmundsson Freysteinn, Schmiedel Tobias, Barker Abigail K, Witcher Taylor
Department of Earth Sciences, Uppsala University, 754 36, Uppsala, Sweden.
Center for Natural Hazards and Disaster Science, Uppsala University, 754 36, Uppsala, Sweden.
Sci Rep. 2024 Jan 10;14(1):962. doi: 10.1038/s41598-023-50880-0.
How the Earth's crust accommodates magma emplacement influences the signals that can be detected by monitoring volcano seismicity and surface deformation, which are routinely used to forecast volcanic eruptions. However, we lack direct observational links between deformation caused by magma emplacement and monitoring signals. Here we use field mapping and photogrammetry to quantify deformation caused by the emplacement of at least 2.5 km of silicic magma in the Reyðarártindur pluton, Southeast Iceland. Our results show that magma emplacement triggered minor and local roof uplift, and that magma reservoir growth was largely aseismic by piecemeal floor subsidence. The occurrence and arrangement of fractures and faults in the reservoir roof can be explained by magmatic overpressure, suggesting that magma influx was not fully accommodated by floor subsidence. The tensile and shear fracturing would have caused detectable seismicity. Overpressure eventually culminated in eruption, as evidenced by exposed conduits that are associated with pronounced local subsidence of the roof rocks, corresponding to the formation of an asymmetric graben at the volcano surface. Hence, the field observations highlight processes that may take place within silicic volcanoes, not accounted for in widely used models to interpret volcanic unrest.
地壳如何容纳岩浆侵入会影响通过监测火山地震活动和地表变形所能检测到的信号，而这些信号通常用于预测火山喷发。然而，我们缺乏岩浆侵入引起的变形与监测信号之间的直接观测联系。在此，我们利用野外测绘和摄影测量来量化冰岛东南部雷扎拉廷杜尔岩体中至少2.5千米厚的硅质岩浆侵入所引起的变形。我们的结果表明，岩浆侵入引发了轻微的局部顶板隆起，并且岩浆储层的增长在很大程度上是通过零星的底板沉降而无震的。储层顶板中裂缝和断层的出现与分布可以用岩浆超压来解释，这表明岩浆注入并未完全通过底板沉降得到容纳。拉伸和剪切破裂本应会引发可检测到的地震活动。超压最终导致了火山喷发，这一点由暴露的管道所证明，这些管道与顶板岩石明显的局部沉降相关，对应于火山表面不对称地堑的形成。因此，野外观测突出了硅质火山内部可能发生的过程，而这些过程在广泛用于解释火山活动的模型中并未得到考虑。
