Propagation of distinct Love-wave pulses from regional to teleseismic distances in continental and oceanic environments
Propagation of distinct Love-wave pulses from regional to teleseismic distances in continental and oceanic environments
复制标题
在大陆和海洋环境中，不同的洛夫波脉冲从区域到远震距离的传播
DOI：
10.1093/gji/ggaa028
复制
发表时间：
2020
影响因子：
2.8
通讯作者：
T. and BLN Kennett
中科院分区：
文献类型：
--
作者：
Furumura;T. and BLN Kennett
面波通常是长波列色散的，振幅随距离稳定衰减。然而，如果群速度在一段时间内几乎是恒定的，那么就会产生一个强脉冲，在很长的距离内保持其振幅。这种情况出现在40-500 s周期带的Love波基模中，地壳和地幔结构的上地幔S波速度具有正梯度。这种在离地球1000米处观测到的具有有限色散的独特洛夫波脉冲被称为G波，以纪念古滕贝格。由大地震引起的长周期G波脉冲将大量能量携带到相当远的距离，在整个地球仪上产生重大影响，例如事件触发。对于没有厚沉积物的地壳结构，产生了类似的G型Love波脉冲，其周期短得多，为10-20 s。这样的脉冲在近区域距离处产生极大的地面位移，例如高估表面波幅度。通过对2016年鸟取中部Mw 6. 2地震和2011年东北近海Mw 9. 0地震的强震观测记录分析，结合地震波传播的三维有限差分模拟和频散曲线分析，研究了G型Love波脉冲在地壳和上地幔中的产生和传播机制。
Surface waves are usually dispersive with long wave trains and steady decay of amplitude with distance. However, if the group velocity is nearly constant for a span of periods a strong pulse is produced that retains its amplitude for large distances. This situation arises for the fundamental mode of Love waves in the period band 40–500 s for crust and mantle structures with a positive gradient ofSwave speed in the uppermost mantle. Such a distinct Love-wave pulse with limited dispersion observed at teleseismic distance is termed theGwave in honour of Gutenberg. The long-periodG-wave pulse caused by large earthquakes carries a large amount of energy to substantial distances, with significant effects across the globe, for example event triggering. A similar G-type Love-wave pulse with a much shorter-period of 10–20 s is generated for crustal structures without thick sediment. Such pulses produce anomalously large ground displacement at near-regional distances with, for example an overestimate of surface wave magnitude. We investigate the generation and propagation mechanism of the G-type Love-wave pulses in the crust and upper-mantle with the analysis of observed strong motion records from theMw6.2 2016 Central Tottori earthquake and theMw9.0 2011 Off Tohoku earthquake in Japan, in conjunction with 3-D finite-difference simulation of seismic wave propagation and analysis of dispersion curves.