Dipartimento di Scienze della Terra, Università di Firenze, 50121, Firenze, Italy.
Dipartimento di Scienze Mineralogiche e Petrologiche, Università di Torino, 10124, Torino, Italy.
Sci Rep. 2017 Jun 20;7(1):3885. doi: 10.1038/s41598-017-03833-3.
Effusive eruptions at open-conduit volcanoes are interpreted as reactions to a disequilibrium induced by the increase in magma supply. By comparing four of the most recent effusive eruptions at Stromboli volcano (Italy), we show how the volumes of lava discharged during each eruption are linearly correlated to the topographic positions of the effusive vents. This correlation cannot be explained by an excess of pressure within a deep magma chamber and raises questions about the actual contributions of deep magma dynamics. We derive a general model based on the discharge of a shallow reservoir and the magmastatic crustal load above the vent, to explain the linear link. In addition, we show how the drastic transition from effusive to violent explosions can be related to different decompression rates. We suggest that a gravity-driven model can shed light on similar cases of lateral effusive eruptions in other volcanic systems and can provide evidence of the roles of slow decompression rates in triggering violent paroxysmal explosive eruptions, which occasionally punctuate the effusive phases at basaltic volcanoes.
喷涌式火山喷发被解释为对岩浆供应量增加引起的不平衡的反应。通过比较斯特龙博利火山（意大利）最近的四次喷发，我们展示了每次喷发排出的熔岩体积如何与喷发口的地形位置呈线性相关。这种相关性不能用深部岩浆室中的压力过剩来解释，这引发了对深部岩浆动力学实际贡献的质疑。我们基于浅部储层的排放和喷口上方的岩浆地壳负荷，得出了一个通用模型，以解释这种线性关系。此外，我们还展示了从喷涌到剧烈爆炸的剧烈转变如何与不同的减压速率相关。我们认为，一个重力驱动的模型可以为其他火山系统中类似的侧向喷涌式喷发提供启示，并为缓慢减压速率在触发剧烈阵发性爆炸喷发中的作用提供证据，这些喷发偶尔会打断玄武岩火山的喷涌阶段。
