Investigating the March 28th 1875 and the September 20th 1920 earthquakes/tsunamis of the Southern Vanuatu arc, offshore Loyalty Islands, New Caledonia
Investigating the March 28th 1875 and the September 20th 1920 earthquakes/tsunamis of the Southern Vanuatu arc, offshore Loyalty Islands, New Caledonia
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DOI：
10.1016/j.tecto.2017.05.006
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发表时间：
2017-07
期刊：
影响因子：
2.9
通讯作者：
M. Ioualalen;B. Pelletier;G. S. Gordillo
中科院分区：
文献类型：
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作者：
M. Ioualalen;B. Pelletier;G. S. Gordillo
新喀里多尼亚的洛亚尔蒂群岛位于太平洋西南部地区，位于瓦努阿图南部高地震俯冲带，因此可能会遭受毁灭性的当地海啸。在过去的 150 年里，1875 年 3 月 28 日和 1920 年 9 月 20 日的大地震引发了两次大海啸。在这项研究中，我们利用对这些海啸的历史观测（主要以证言的形式）、地震情景和海啸模型来推导这些地震的震级，以及海啸上升和淹没图。假设这些地震位于板间巨型逆冲带，则1875年地震震级为Mw8.1~8.2，1920年地震震级为Mw7.5~7.8。海啸对利富岛和马雷岛造成的损失与这些震级大致成正比，其中马雷岛由于有利的波浪方向性而受到的影响较小。由于共振的影响，乌韦阿岛的损坏程度可能不规则变化。这项研究表明，历史海啸地震的定量特征可以从海啸爆发的定性估计中得出。
New Caledonia's Loyalty Islands are located in the southwest region of the Pacific ocean in the highly seismogenic southern Vanuatu subduction zone and therefore may be subject to devastating local tsunamis. Over the past 150 years, two large tsunamis were triggered by major earthquakes on March 28th 1875 and September 20th 1920. In this study, we use historical observations of these tsunamis (mostly in the form of testimonials), earthquake scenarios, and tsunami modeling to derive the magnitudes of these earthquakes, as well as tsunami runup and inundation maps. Assuming that these earthquakes were located on the interplate megathrust zone, the 1875 earthquake's magnitude wasMw8.1–8.2 and the 1920 event's magnitude wasMw7.5–7.8. The tsunami damage inflicted on the Lifou and Maré islands was approximately proportional to these magnitudes, with Maré being less impacted due to favorable wave directivity. Damage at Ouvéa island may have varied irregularly with the magnitude due to the effects of resonance. This study demonstrates that the quantitative characteristics of historical tsunamigenic earthquakes may be derived from qualitative estimates of tsunami runup.