The seismic crisis unfolding in the Azores: earthquakes accompanying a rarely observed submarine eruption?

亚速尔群岛正在发生的地震危机：地震伴随着罕见的海底喷发？

• 批准号: NE/T014814/1
• 负责人: Neil Mitchell
• 金额: $ 1.68万
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FT014814%2F1
• 关键词: seismic; crisis; unfolding; Azores; earthquakes

A swarm of earthquakes on the seabed west of a volcanic island in the Azores (Faial) presents an exciting opportunity to find out potentially how submarine volcanic cones form and this in turn helps us to understand the risks from submarine eruptions. The swam lies at one end of an elongated volcano (Condor Seamount) where there are small volcanic cones and ridges. We will install 4 seismometers on the seabed around the site to record further earthquakes over two months. By accurately locating those earthquakes, we will be able to determine the geometries of faults and cracks filled with lava (dykes). If there has been an eruption, the seabed will have changed shape - this will be worked out from multibeam echo-sounder data collected in a new sonar survey in the summer of 2020. The combined results will show us whether there has been an eruption and if so how that eruption related to the molten lava supplied deeper in the Earth. In addition, we will be able to reassess seismic waves that have travelled through the adjacent submarine volcano to see if those waves have unusually low velocities expected for a magma chamber. The new results from the seismometers will be used to update software used by government scientists in the Azores to work out where earthquakes occur and their magnitudes, hence their monitoring service for the local population. This will further help us work out the nature of the earthquake swarm (whether associated with subterranean movement of lava or movements on faults). Submarine volcanic eruptions are less frequent in the Atlantic compared with the Pacific Ocean, but are a risk to ships, seabed cables and to local populations where associated earthquakes and landslides cause tsunamis. Understanding this Azorean event will help characterize this broader threat, of importance to the UK given its large sea areas, including those around volcanically active Ascension and Tristan da Cunha islands.

在亚速尔群岛火山岛(Faial)以西的海床上发生的一系列地震为我们提供了一个令人兴奋的机会，可以潜在地发现海底火山锥是如何形成的，这反过来又有助于我们了解海底喷发的风险。游泳者位于一座细长的火山(秃鹰海山)的一端，那里有小的火山锥体和山脊。我们将在现场周围的海床上安装4台地震仪，以记录两个月内的进一步地震。通过准确定位这些地震，我们将能够确定断层和充满熔岩(岩墙)的裂缝的几何形状。如果发生了喷发，海床的形状就会改变--这将通过2020年夏天一项新的声纳调查中收集的多波束回声测深仪数据得出。综合的结果将向我们显示是否发生了喷发，如果是的话，那次喷发与地球深处供应的熔岩有何关系。此外，我们将能够重新评估穿过邻近海底火山的地震波，看看这些波是否具有预期的岩浆室异常低的速度。地震仪的新结果将用于更新亚速尔群岛政府科学家使用的软件，以计算出地震发生的地点和震级，从而为当地人口提供监测服务。这将进一步帮助我们弄清震群的性质(无论是与熔岩的地下运动还是与断层上的运动有关)。与太平洋相比，大西洋海底火山喷发的频率较低，但对船只、海底电缆和当地居民构成风险，因为相关的地震和山体滑坡会导致海啸。了解这一Azorean事件将有助于描述这一更广泛的威胁，鉴于英国的大片海域，包括火山活跃的阿森松岛和特里斯坦-达库尼亚群岛周围的海域，这一威胁对英国非常重要。

项目成果

Emplacement history of volcaniclastic turbidites around the central Azores volcanic islands: Frequencies of slope landslides and eruptions

• DOI: 10.1130/ges02570.1
• 发表时间: 2023-03
• 期刊: Geosphere
• 影响因子: 2.5
• 作者: Yu-Chun Chang;N. Mitchell;J. Schindlbeck‐Belo;T. Hansteen;A. Freundt;Christian Hübscher;R. Quartau