Historical tsunami earthquakes in the Southwest Pacific: An extension to Δ > 80° of the energy-to-moment parameter Θ
Historical tsunami earthquakes in the Southwest Pacific: An extension to Δ > 80° of the energy-to-moment parameter Θ
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西南太平洋历史海啸地震：能量矩参数 θ 延伸至 Δ > 80°
DOI：
10.1093/gji/ggx197
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发表时间：
2017
影响因子：
2.8
通讯作者：
N. Saloor
中科院分区：
文献类型：
--
作者：
E. Okal;N. Saloor
总结 我们将 Newman 和 Okal 引入的能量-时刻慢度参数的计算扩展到 80° 以上的距离，通过定义基于遥远站点记录的区域经验校正，以进行常规研究。反过来，该过程允许在类似的源站几何结构中研究地震，但唯一可用的数据位于原始距离阈值之外，特别是在短周期地震仪密集网络发展之前的历史地震的情况下。该方法适用于 1947 年新西兰 Hikurangi 海岸发生的两次地震，我们确认了海啸地震的慢度参数特征。此外，我们还确定了 1934 年 7 月 21 日在圣克鲁斯群岛发生的大余震，该余震发生在最近的 2013 年地震附近，这也被视为海啸地震。在该俯冲带，对近期和前数字化事件的系统汇编显示了与受化石结构俯冲控制的当地构造体系相关的缓慢性的多样性。我们的方法也很好地适应了大地震的模拟记录的情况，对于这种情况，常规距离的短周期地震图常常超出比例。
S U M M A R Y We extend to distances beyond 80◦ the computation of the energy-to-moment slowness parameter introduced by Newman and Okal, by defining a regional empirical correction based on recordings at distant stations for events otherwise routinely studied. In turn, this procedure allows the study of earthquakes in a similar source-station geometry, but for which the only available data are located beyond the original distance threshold, notably in the case of historical earthquakes predating the development of dense networks of short-period seismometers. This methodology is applied to the twin 1947 earthquakes off the Hikurangi coast of New Zealand for which we confirm slowness parameters characteristic of tsunami earthquakes. In addition, we identify as such the large aftershock of 1934 July 21 in the Santa Cruz Islands, which took place in the immediate vicinity of the more recent 2013 shock, which also qualifies as a tsunami earthquake. In that subduction zone, the systematic compilation of for both recent and pre-digital events shows a diversity in slowness correlating with local tectonic regimes controlled by the subduction of fossil structures. Our methodology is also well adapted to the case of analogue records of large earthquakes for which short-period seismograms at conventional distances are often off-scale.