当前位置: X-MOL 学术J. South Am. Earth Sci. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Rhyolitic volcano dynamics in the Southern Andes: Contributions from 17 years of InSAR observations at Cordón Caulle from 2003 to 2020
Journal of South American Earth Sciences ( IF 1.8 ) Pub Date : 2021-03-01 , DOI: 10.1016/j.jsames.2020.102841
Francisco Delgado

Abstract In this article I present a review of InSAR observations of ground deformation at Cordon Caulle volcano, whose 2011–2012 VEI 4-5 eruption is the best scientifically observed and instrumentally recorded rhyolitic eruption to date. I document a complete cycle of pre-eruptive uplift, co-eruptive subsidence and post-eruptive uplift with InSAR data between March 2003 and May 2020, and produced by a complex interplay of magmatic processes. Pre-eruptive data show ~ 0.5 m of ground uplift in three distinct episodes between 2003 and 2011, with uplift rates between ~ 3 and ~ 30 cm/yr. The uplift was likely caused by magma injection resulting in pressurization of the magmatic system at depths of 4–9 km. Data spanning the first 3 days of the eruption show ~ 1.5 m of deflation produced by two distinct sources at 4–6 km depth located 18 km from each other and up to 10 km from the eruptive vent -- suggesting hydraulic connectivity of a large magma mush zone. A third source of deformation was recorded during the rest of the eruption at a depth of ~ 5 km, resulting in a total subsidence of ~ 4.2 m during the whole eruption. On a much smaller spatial scale ( ~ 25 km2), InSAR-derived digital elevation models recorded ~ 250 m of uplift in the area of the eruptive vent interpreted as the intrusion of a shallow laccolith during the first 2.5 months of the eruption and time averaged lava discharge rates up to ~ 150 m3/s. The co-eruptive time series of reservoir pressure drop and extruded volume follow exponential trends that can be explained by a model of magma reservoir depressurization and conduit flow. Since the end of the eruption, the surface of the volcano was uplifted ~ 1 m in a sequence of three transient episodes of unrest during 2012 and 2019, with uplift rates between 6 and 45 cm/yr and lasting between 0.5 and 3.2 years. These pulses can be modeled by the same source, a sub-horizontal sill at a depth of ~ 6 km. Viscoelastic relaxation is not significant on these time scales, hence I interpret these uplift signals as being produced by episodic pulses of magma injection in the crystal mush that likely underlies the volcano. The episodic and abrupt changes of the ground deformation suggest a restless trans-lateral magmatic system at depths of 4–9 km, and active across multiple spatial and temporal scales. Finally, I also discuss challenges of the InSAR technology that should be addressed to detect ground deformation on short time scales, particularly under the low coherence conditions of Cordon Caulle.

中文翻译:

安第斯山脉南部流纹岩火山动力学:2003 年至 2020 年 Cordón Caulle 17 年 InSAR 观测的贡献

摘要 在这篇文章中,我回顾了对 Cordon Caulle 火山地面变形的 InSAR 观测,该火山 2011-2012 年的 VEI 4-5 喷发是迄今为止科学观测和仪器记录最好的流纹岩喷发。我用 2003 年 3 月至 2020 年 5 月的 InSAR 数据记录了喷发前隆起、协同喷发下沉和喷发后隆起的完整循环,并由岩浆过程的复杂相互作用产生。喷发前数据显示,在 2003 年至 2011 年之间的三个不同事件中,地面抬升约 0.5 米,抬升速率在约 3 至约 30 厘米/年之间。隆起很可能是由岩浆注入导致岩浆系统在 4-9 公里深处加压引起的。喷发前 3 天的数据显示 ~ 1。由两个不同来源在 4-6 公里深度产生的 5 米紧缩,彼此相距 18 公里,距离喷发口长达 10 公里——表明大型岩浆糊带的水力连通性。在余下的喷发过程中记录了第三个变形源,深度约 5 公里,导致整个喷发期间总沉降约 4.2 m。在更小的空间尺度(~25 平方公里)上,InSAR 衍生的数字高程模型记录了喷发口区域约 250 米的隆起,解释为在喷发的前 2.5 个月内有浅层石板侵入,平均时间熔岩排放率高达 ~ 150 m3/s。储层压降和挤压体积的协同喷发时间序列遵循指数趋势,可以通过岩浆储层降压和管道流动模型来解释。自喷发结束以来,火山表面在 2012 年和 2019 年期间连续发生了 3 次短暂的动荡,隆起约 1 m,隆升速率在 6 至 45 厘米/年之间,持续时间在 0.5 至 3.2 年之间。这些脉冲可以由同一个源模拟,即深度约 6 公里的亚水平地基。粘弹性松弛在这些时间尺度上并不显着,因此我将这些隆起信号解释为由可能位于火山下方的晶体糊状物中的岩浆注入的偶发脉冲产生。地面变形的偶发性和突变性表明在4-9公里深度存在一个不安定的横向岩浆系统,并在多个时空尺度上活跃。最后,我还讨论了 InSAR 技术在短时间尺度上检测地面变形应解决的挑战,
更新日期:2021-03-01
down
wechat
bug