Tsunamis and submarine landslides in Suruga Bay, central Japan, caused by Nankai?Suruga Trough megathrust earthquakes during the last 5000 years
Tsunamis and submarine landslides in Suruga Bay, central Japan, caused by Nankai?Suruga Trough megathrust earthquakes during the last 5000 years
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近5000年来南海骏河海槽巨型逆冲地震引发日本中部骏河湾海啸和海底山体滑坡
DOI：
10.1016/j.quascirev.2020.106527
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发表时间：
2020
影响因子：
4
通讯作者：
Yoda Yuki
中科院分区：
文献类型：
--
作者：
Kitamura Akihisa;Yamada Kazuyoshi;Sugawara Daisuke;Yokoyama Yusuke;Miyairi Yosuke;Hirakawa Miki;Iwatsuki Daichi;Katagiri Satoru;Maeda Masaya;Mori Hideki;Nakai Yuki;Okazaki Sota;Sakamoto Yui;Sasada Masaki;Seki Yusuke;Takikawa Youki;Yamamoto Yuka;Yoda Yuki
在日本西南部沿海地区，每隔100 - 150年就会发生一次8级大规模逆冲地震，造成波高大于5米的大海啸，发生在标志着欧亚板块和菲律宾海板块会聚边界的南海-骏贺海槽沿线。利用沉积学、地球化学和古生物学分析，以及14 C测年，我们研究了从面向骏河海槽的静冈烧津平原的滨留低地收集的12个沉积岩芯中的海啸沉积物。在过去5000年沉积的沉积物中识别出四个桑迪海啸沉积物（砂1 - 4）。砂1沉积于公元前805年至公元前405年之间，这表明在公元前3090年至公元前2913年的4000年期间，只有一次海啸在滨留低地泻湖留下了沉积学印记，以及公元1096年的Eicho-Tokai地震。这种非常低的海啸淹没频率可能表明，这次海啸比那些通常与大型逆冲断层地震有关的海啸更大。砂2 - 4分别与Eicho-Tokai，AD 1361 Shohei-Koan和AD 1498 Meio-Tokai地震相关的海啸相关。我们的数据表明，一个沙嘴，以前保护泻湖从海浪，突然被摧毁后，公元1096年Eicho-Tokai地震，并没有重新形成在同一位置。沙嘴的消失被推断为地震引起的海底滑坡。本文中提出的数据，以及从历史文献中获得的信息，表明在公元1096年和公元1498年的M8巨型逆冲断层地震造成的海底滑坡在研究区，导致海岸沉降和沿海地区的破坏所造成的海啸。
Magnitude 8 megathrust earthquakes that have generated large tsunamis with wave heights of >5 m in coastal areas of southwestern Japan have occurred every 100–150 years along the Nankai–Suruga Trough, which marks the convergent boundary between the Eurasian and Philippine Sea plates. Using sedimentological, geochemical, and paleontological analyses, as well as14C dating, we examined tsunami deposits in 12 sediment cores collected from the Hamatome lowland, Yaizu Plain, Shizuoka, which faces the Suruga Trough. Four sandy tsunami deposits (Sands 1–4) are identified in sediments deposited during the last 5000 years. Sand 1 was deposited between 805 and 405 BC, suggesting that only one tsunami left a sedimentological imprint in the Hamatome lowland lagoon during the period of ∼4000 years between 3090 and 2913 BC and the AD 1096 Eicho-Tokai earthquake. This very low frequency of tsunami inundation may suggest that this tsunami was larger than those typically associated with megathrust earthquakes. Sands 2–4 are correlated with tsunamis associated with the Eicho-Tokai, AD 1361 Shohei-Koan, and AD 1498 Meio-Tokai earthquakes, respectively. Our data indicate that a sand spit, which had previously protected the lagoon from oceanic waves, was abruptly destroyed following the AD 1096 Eicho-Tokai earthquake and did not re-form at the same location. This disappearance of the sand spit is inferred to have involved an earthquake-induced submarine landslide. The data presented in this paper, together with information obtained from historical documents, indicates that M8 megathrust earthquakes in AD 1096 and AD 1498 caused submarine landslides in the study area, resulting in coastal subsidence and damage to coastal areas additional to that caused by the tsunamis.