Mordret A, Brenguier F, Causse M, Boué P, Voisin C, Dumont I, Vernon F L, Ampuero J P
Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre Grenoble France.
TOTAL CSTJF Pau France.
Geophys Res Lett. 2020 Sep 16;47(17):e2020GL088563. doi: 10.1029/2020GL088563. Epub 2020 Sep 2.
Although moderate-size earthquakes are poorly studied by lack of near-fault observations, they can provide key information about larger damaging earthquakes. Here we propose a new approach, inspired by double-difference relocation, that uses high-coherency waveforms recorded at neighboring sensors, to study the preparation phase and dynamics of moderate-size earthquakes. We validate this technique by analyzing the 2016, 5.2 Borrego Springs earthquake in Southern California and find consistent rupture velocities of 2 km/s highlighting two main rupture asperities. The analysis of the 2019, l5.2 Le Teil earthquake in France reveals slow nucleation at depth that migrates to the surface and propagates northward with a velocity of ∼2.8 km/s, highlighting two main rupture events also imaged by InSAR. By providing unprecedented resolution in our observation of the rupture dynamics, this approach will be useful in better understanding the preparation phase and rupture of both tectonic and induced earthquakes.
尽管由于缺乏近断层观测,中等规模地震的研究较少,但它们可以提供有关更大破坏性地震的关键信息。在此,我们受双差定位启发提出一种新方法,该方法利用相邻传感器记录的高相干波形,来研究中等规模地震的孕震阶段和动力学。我们通过分析2016年发生在南加州的5.2级博雷戈斯普林斯地震来验证这项技术,发现其破裂速度一致为2千米/秒,突出了两个主要破裂asperities。对2019年发生在法国的5.2级勒泰伊地震的分析显示,震源在深度处缓慢成核,然后迁移到地表并以约2.8千米/秒的速度向北传播,突出了两个主要破裂事件,干涉合成孔径雷达(InSAR)也对其进行了成像。通过在我们对破裂动力学的观测中提供前所未有的分辨率,这种方法将有助于更好地理解构造地震和诱发地震的孕震阶段及破裂过程。