Energetic Onset of Earthquakes
Energetic Onset of Earthquakes
复制标题
DOI：
10.1029/2018gl080687
复制
发表时间：
2019-03-16
影响因子：
5.2
通讯作者：
Denolle, Marine A.
中科院分区：
文献类型：
--
作者：
Denolle, Marine A.
地震辐射是宽带的，其时间演化带有破裂过程的地震特征。我使用已建立和开发的新的观测指标来量化辐射能量（地震功率）和随时间变化的尺度辐射能量的时间变化。矩率、地震功率和标度能量的通用函数形式来自于全球源时间函数数据库。地震在破裂发展的早期阶段，即整个破裂持续时间的前10-30%，辐射最多，效率最高。这一结果与地震震级、深度和震源机制无关。除了解释震源持续时间和辐射能量变化的弹性特性与深度的深度相关性外，浅震和深震之间在功能形式上也存在细微差异。深层地震的发展速度比浅层地震慢，但它们的地震功率峰值更高。当地震发生时，它们释放滑动并激发地面运动。大滑移控制低频地震动，但产生破坏性地震动的是滑移率的非均匀性。该研究为系统地探索震源处高频地震动的时间演化和推导激发高频地震波的震源生产力提供了新的途径。我使用了一个全球震源时间函数数据库来显示，在破裂持续时间的前10-30%发生的早期生长阶段，在产生地震波方面非常有效。深层地震的发展速度较慢，但总体上发射出更多的地面运动。
Earthquake radiation is broadband, and its temporal evolution carries the seismic signature of the rupture process. I use established and develop new observational metrics to quantify the temporal variation in radiated energy (seismic power) and in a time-dependent scaled radiated energy. Universal functional forms of moment rate, seismic power, and scaled energy arise from a global database of source time functions. Earthquakes radiate mostly and most efficiently in the early stage of development of the rupture that is in the first 10-30% of the overall rupture duration. This result is independent of earthquake magnitude, depth, and focal mechanism. Beyond depth dependence in elastic properties with depth that explain variations in source duration and radiated energy, subtle differences in functional forms exist between shallow and deep earthquakes. Deep events have a slower development than shallow earthquakes, but they carry a higher peak in seismic power.Plain Language Summary When earthquakes occur, they release slip and excite ground motions. A large slip controls the low-frequency ground motions, but it is heterogeneity of rate of slip that generates the damaging ground motions. This study provides new approaches to systematically explore the temporal evolution of the high-frequency ground motions at the source and deduce a source productivity to excite the high-frequency seismic waves. I use a global database of earthquake source time functions to show that an early growth phase, which occurs in the first 10-30% of the rupture duration, is highly effective at generating seismic waves. Deep earthquakes are slower at developing but emit more ground motions overall.