Seismic Amplitude Ratio Analysis of the 2014-2015 Bárarbunga-Holuhraun Dike Propagation and Eruption
Seismic Amplitude Ratio Analysis of the 2014-2015 Bárarbunga-Holuhraun Dike Propagation and Eruption
复制标题
2014-2015年Bárarbunga-Holuhraun堤坝扩展和喷发地震振幅比分析
DOI：
10.1002/2017jb014660
复制
发表时间：
2018
期刊：
影响因子：
3.4
通讯作者：
Caudron C
中科院分区：
文献类型：
--
作者：
Caudron C
岩浆在脆性岩石中通过岩脉和岩床运移。这种运动可能伴随着地震能量的释放，可以从地球表面跟踪。因此，确定岩脉的位置并破译其动态对于理解和预测火山爆发至关重要。地震振幅比分析（SARA）方法的目的是使用地震台网记录的振幅来跟踪熔体的传播，而不需要拾取单个地震相位的到达时间。这项研究通过比较SARA位置（在2和16 Hz之间过滤）与2014-2015年冰岛Bár arbunga‐Holuhraun堤坝入侵和喷发期间记录的地震位置（相同频带）来验证这种方法。整合这两种方法也提供了机会，调查岩浆迁移的时空特征，在岩脉侵入和随后的喷发。在侵入期间，SARA位置与地震位置非常一致。但也有几个例外。(1)低频信号可能与8月23日的冰下喷发有关。(2)一个系统的撤退的地震活动也被观察到后面的每个活动段在停滞阶段，并与一个更大的空间范围内的地震能量源。这种行为可以通过堤的形状和/或通过堤膨胀来控制。(3)在喷发期间，SARA的位置始终集中在喷发地点。(4)9月3日，冰釜附近出现了丰富的震颤信号。这项研究证明了SARA方法的力量，提供了强大的网站放大;质量因子和地震速度可用。
Magma is transported in brittle rock through dikes and sills. This movement may be accompanied by the release of seismic energy that can be tracked from the Earth's surface. Locating dikes and deciphering their dynamics is therefore of prime importance in understanding and potentially forecasting volcanic eruptions. The Seismic Amplitude Ratio Analysis (SARA) method aims to track melt propagation using the amplitudes recorded across a seismic network without picking the arrival times of individual earthquake phases. This study validates this methodology by comparing SARA locations (filtered between 2 and 16 Hz) with the earthquake locations (same frequency band) recorded during the 2014–2015 Bár arbunga‐Holuhraun dike intrusion and eruption in Iceland. Integrating both approaches also provides the opportunity to investigate the spatiotemporal characteristics of magma migration during the dike intrusion and ensuing eruption. During the intrusion SARA locations correspond remarkably well to the locations of earthquakes. Several exceptions are, however, observed. (1) A low‐frequency signal was possibly associated with a subglacial eruption on 23 August. (2) A systematic retreat of the seismicity was also observed to the back of each active segment during stalled phases and was associated with a larger spatial extent of the seismic energy source. This behavior may be controlled by the dike's shape and/or by dike inflation. (3) During the eruption SARA locations consistently focused at the eruptive site. (4) Tremor‐rich signal close to ice cauldrons occurred on 3 September. This study demonstrates the power of the SARA methodology, provided robust site amplification; Quality Factors and seismic velocities are available.