Deep long period seismicity preceding and during the 2021 Fagradalsfjall eruption, Iceland
Deep long period seismicity preceding and during the 2021 Fagradalsfjall eruption, Iceland
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2021 年冰岛 Fagradalsfjall 喷发之前和期间的深层长周期地震活动
DOI：
10.1007/s00445-022-01603-2
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发表时间：
2022
影响因子：
3.5
通讯作者：
Greenfield T
中科院分区：
文献类型：
--
作者：
Greenfield T
我们使用冰岛雷克雅未克半岛上的密集地震网络，对2021年Fagradalsfjall火山喷发点东北2公里处10-12公里深度的一组地震进行成像。与位于上部脆性地壳的地震相比，这些深源地震的频率较低，与冰岛和世界各地其他火山观测到的深源长周期（DLP）地震活动相似。我们在研究期开始（2020年6月）和2021年3月爆发前长达3周的堤坝入侵开始之间观察到了几次DLP地震群。在喷发过程中，DLP地震群返回1公里的西南原来的位置期间，当放电率或喷泉式的喷发发生变化。因此，DLP地震活动可能与Fagradalsfjall下方的岩浆管道系统有关。然而，DLP地震活动发生浅约5公里，比岩石学模型放置近莫霍岩浆储存区，其中Fagradalsfjall熔岩存储。我们认为，DLP地震活动是由富CO2流体的出溶或岩浆运动在下地壳中的熔体输送障碍触发的。通过岩浆管道系统在喷发过程中增加的流量可能会增加熔体迁移过程的复杂性，从而导致进一步的DLP地震活动，尽管同期岩浆通道的表面。
We use a dense seismic network on the Reykjanes Peninsula, Iceland, to image a group of earthquakes at 10–12 km depth, 2 km north-east of 2021 Fagradalsfjall eruption site. These deep earthquakes have a lower frequency content compared to earthquakes located in the upper, brittle crust and are similar to deep long period (DLP) seismicity observed at other volcanoes in Iceland and around the world. We observed several swarms of DLP earthquakes between the start of the study period (June 2020) and the initiation of the 3-week-long dyke intrusion that preceded the eruption in March 2021. During the eruption, DLP earthquake swarms returned 1 km SW of their original location during periods when the discharge rate or fountaining style of the eruption changed. The DLP seismicity is therefore likely to be linked to the magma plumbing system beneath Fagradalsfjall. However, the DLP seismicity occurred ~ 5 km shallower than where petrological modelling places the near-Moho magma storage region in which the Fagradalsfjall lava was stored. We suggest that the DLP seismicity was triggered by the exsolution of CO2-rich fluids or the movement of magma at a barrier to the transport of melt in the lower crust. Increased flux through the magma plumbing system during the eruption likely adds to the complexity of the melt migration process, thus causing further DLP seismicity, despite a contemporaneous magma channel to the surface.
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发表时间：
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期刊：
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影响因子：
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