Event classification, seismicity, and eruption forecasting at Great Sitkin Volcano, Alaska: 1999–2023

IF 2.4 3区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY
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引用次数: 0

Abstract

The frequency content of volcanogenic seismicity is often used to classify events and their spatial and temporal progression is then used to map subsurface volcanic processes. The progression of volcano-seismic events and associated source processes also plays a critical role in eruption forecasting. Here we develop and evaluate a computerized methodology for characterizing volcano-seismic event types using Frequency Index and Average Peak Frequency. We apply and test this technique at Great Sitkin Volcano, Alaska, classifying over 9000 hypocenters between 1999 and 2023. This 24-year time span covers periods of seismic quiescence, earthquake activity on nearby tectonic (bookshelf) faults, precursory unrest from 2016 to 2021, and the explosive onset in May 2021 of the ongoing effusive eruption. We use the spatial and temporal evolution of classified event types to map the active volcanic and tectonic processes, develop a conceptual model of the subsurface magmatic system, and perform a retrospective analysis of eruption forecasts at Great Sitkin Volcano between 2016 and the present. The classification and progression of hypocenters suggests the subsurface Great Sitkin Volcano magmatic system consists of a mid- to lower- crustal source zone between 10 and 40 km depth and an upper crustal magma storage area between −1 and 10 km depth (hypocenter depth is referenced to sea level and negative depths reflect height above sea level). The earliest precursors occurred in July 2016 and consisted of deep long-period and volcano-tectonic earthquakes at mid-crustal depths suggesting the subsequent unrest and eruption were triggered by a deeper intrusion of magma. This mid-crustal seismic activity was immediately followed by the onset upper-crustal long-period events and volcano-tectonic earthquakes VTs suggesting a strong linkage between the shallow and deeper portions of the magmatic system. The upper crustal area was likely capped by the 1974 lava dome until the magmatic explosion on May 26, 2021.

阿拉斯加大锡特金火山的事件分类、地震和喷发预报:1999-2023 年
火山地震的频率含量通常用于对事件进行分类,然后利用其空间和时间进展来绘制地下火山过程图。火山地震事件的进展和相关的震源过程在火山爆发预报中也起着至关重要的作用。在这里,我们开发并评估了一种计算机化方法,利用频率指数和平均峰值频率来描述火山地震事件类型。我们在阿拉斯加大锡特金火山应用并测试了这一技术,在 1999 年至 2023 年期间对 9000 多个次中心进行了分类。这 24 年的时间跨度涵盖了地震静止期、附近构造(书架)断层的地震活动期、2016 年至 2021 年的前兆动乱期,以及 2021 年 5 月正在进行的喷发爆发期。我们利用分类事件类型的空间和时间演变来绘制活火山和构造过程图,建立地下岩浆系统的概念模型,并对 2016 年至今大锡金火山的喷发预报进行回顾性分析。低中心的分类和发展表明,大锡特金火山地下岩浆系统由深度在10至40千米之间的中下地壳源区和深度在-1至10千米之间的上地壳岩浆储存区组成(低中心深度参考海平面,负深度反映海平面以上的高度)。最早的前兆发生在 2016 年 7 月,由地壳中层深度的深长周期和火山构造地震组成,表明随后的动荡和喷发是由更深的岩浆侵入引发的。在地壳中层地震活动之后,紧接着又发生了地壳上层长周期地震和火山构造地震,这表明岩浆系统的浅层和深层部分之间存在紧密联系。在 2021 年 5 月 26 日岩浆爆炸之前,地壳上部区域很可能被 1974 年的熔岩穹丘所覆盖。
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来源期刊
CiteScore
5.90
自引率
13.80%
发文量
183
审稿时长
19.7 weeks
期刊介绍: An international research journal with focus on volcanic and geothermal processes and their impact on the environment and society. Submission of papers covering the following aspects of volcanology and geothermal research are encouraged: (1) Geological aspects of volcanic systems: volcano stratigraphy, structure and tectonic influence; eruptive history; evolution of volcanic landforms; eruption style and progress; dispersal patterns of lava and ash; analysis of real-time eruption observations. (2) Geochemical and petrological aspects of volcanic rocks: magma genesis and evolution; crystallization; volatile compositions, solubility, and degassing; volcanic petrography and textural analysis. (3) Hydrology, geochemistry and measurement of volcanic and hydrothermal fluids: volcanic gas emissions; fumaroles and springs; crater lakes; hydrothermal mineralization. (4) Geophysical aspects of volcanic systems: physical properties of volcanic rocks and magmas; heat flow studies; volcano seismology, geodesy and remote sensing. (5) Computational modeling and experimental simulation of magmatic and hydrothermal processes: eruption dynamics; magma transport and storage; plume dynamics and ash dispersal; lava flow dynamics; hydrothermal fluid flow; thermodynamics of aqueous fluids and melts. (6) Volcano hazard and risk research: hazard zonation methodology, development of forecasting tools; assessment techniques for vulnerability and impact.
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