Investigating long-period and ultra-long-period oscillations in magma density of the current Cumbre Vieja eruption on La Palma (Canary Islands, Spain)

研究拉帕尔马岛（西班牙加那利群岛）当前 Cumbre Vieja 喷发的岩浆密度的长周期和超长周期振荡

• 批准号: NE/W009455/1
• 负责人: Joachim Gottsmann
• 金额: $ 5.4万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FW009455%2F1
• 关键词: Investigating; long; period; ultra; oscillations

Volcanic eruptions in the Canary Islands are rare events. They occur on average every few couple of decades to centuries. In mid-September 20 21 and eruption started on La Palma after a 50 year hiatus in eruptive activity on the island. It has now become clear that this eruption is the largest eruption on La Palma in several thousands of years and probably among the largest eruptions in the archipelago in several thousands of years.The eruption started out as a fissure eruption feeding magma to form several lava flows. At the end of October the eruption style changed drastically turning increasingly explosive with the advent of giant lava fountains reaching heights in excess of 600 m above the event.This change in activity requires drastic changes in magma density as magma rises from depth to erupt at the surface. We suspect a reduction in density by a factor of 2 to 3. However, there is currently no instrumentation on La Palma which can shed light on these density changes. This project aims at quantifying magma density changes by installing a network of three gravimeters: geophysical instruments that are sensitive to density changes at depth. The gravimeters will be strategically installed atop of magma reservoirs that we now know are connected between 35 km and around 5 km depth to feed the current eruption. Based on preliminary findings from project partners, the plumbing system of the eruption is geometrically complex and requires substantial lateral flow of magma from an intermediate-level magma storage at around 10 km depth to the most shallow storage at around 5 km depth. There is now the opportunity to study the drastic variations in density along the path of magma in unprecedented detail. Theoretical models of magma replenishment indicate variations in physical properties of magma such as density over periods of hours to weeks. The eruption on La Palma provides us with hence an unprecedented and unique opportunity to test these theories. We will be able to quantify not only the variations in magma density but also its evolution in time and space using advanced numerical models and data interrogation tools. Furthermore we can link our findings with the dynamics of the eruption that is captured by publicly available video footage to study the relationship between magma density changes and eruptive activity. This will afford us with new insights into processes within the plumbing system of the current eruption in La Palma and also more broadly for similar eruptions elsewhere in the archipelago and other volcanic ocean islands. Ultimately, there is scope in project to evaluate the benefit of gravimetric networks to aid eruption forecasting and hazard assessment.

加那利群岛的火山喷发是罕见的事件。它们平均每几十年到几个世纪发生一次。在岛上的喷发活动中断了50年后，于20、21、21和9月中旬，拉帕尔马开始喷发。现在已经清楚的是，这次喷发是拉帕尔马几千年来最大的一次喷发，也可能是几千年来该群岛最大的喷发之一。喷发最初是一次裂缝喷发，为岩浆提供了几个熔岩流。10月底，随着巨型熔岩喷泉的出现，喷发方式发生了巨大的变化，喷发变得越来越爆炸性。这种活动的变化要求岩浆从深处上升到地表喷发时，岩浆密度发生剧烈变化。我们怀疑密度减少了2到3倍。然而，目前在拉帕尔马上还没有仪器可以揭示这些密度变化。该项目旨在通过安装一个由三个重力仪组成的网络来量化岩浆密度的变化，这三个重力仪是对深部密度变化敏感的地球物理仪器。重力仪将战略性地安装在岩浆储集层的顶部，我们现在知道这些储集层连接在35公里到大约5公里深之间，以满足当前的喷发。根据项目伙伴的初步发现，火山喷发的管道系统在几何上很复杂，需要大量的岩浆横向流动，从大约10公里深的中层岩浆储存到大约5公里深度的最浅储存。现在有机会以前所未有的细节研究岩浆路径上密度的剧烈变化。岩浆补充的理论模型表明，岩浆物理性质的变化，如密度在几小时到几周的时间内的变化。因此，拉帕尔马火山喷发为我们提供了一个前所未有的、独特的机会来检验这些理论。我们将使用先进的数值模型和数据查询工具，不仅能够量化岩浆密度的变化，而且能够量化其在时间和空间上的演变。此外，我们可以将我们的发现与公开提供的视频片段捕捉到的喷发动态联系起来，以研究岩浆密度变化和喷发活动之间的关系。这将使我们对目前拉帕尔马火山喷发的管道系统内的过程有新的见解，也将更广泛地为群岛和其他火山海岛屿的其他类似喷发提供新的见解。归根结底，项目中还有评估重力网络的益处以帮助火山喷发预报和危险评估的余地。