Geological and Sedimentological Evidence of a Large Tsunami Occurring ~1100 Year BP from a Small Coastal Lake along the Bay of La Paz in Baja California Sur, Mexico
Geological and Sedimentological Evidence of a Large Tsunami Occurring ~1100 Year BP from a Small Coastal Lake along the Bay of La Paz in Baja California Sur, Mexico
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墨西哥南下加利福尼亚州拉巴斯湾沿岸小湖发生距今约 1100 年的大型海啸的地质和沉积学证据
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
Kam‐biu Liu
中科院分区：
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作者：
T. McCloskey;T. Bianchette;Kam‐biu Liu
封闭水体中的小规模地震事件的重要性通常被忽视，因为它可能导致能够对地理上受限的小区域造成全面破坏的大海啸波，尽管认识到此类事件的发生是充分评估特定地点自然灾害风险的一个必要因素。在这里，我们提出了一个可能的大型局部性海啸的证据，该海啸发生在距今约1100年(BP)以前的南下加利福尼亚州拉巴斯海湾内，导致在平均高水位(MHW)以上约2m处形成了一个雪莱海脊。这个海脊由一个连续的楔形海沙和贝壳组成，这些沙子和贝壳约50厘米深，沿着整个湖面朝海的边缘沉积。从湖泊周围的陆地环境中收集的海洋贝壳包括来自各种环境的物种，包括最低首选深度为13米的近海物种。有证据表明，这些贝壳很可能是由一场海啸沉积的，海啸的高度在MHW以上2-3.6米，可能与墨西哥湾构造活跃的东部边缘的一个岛屿的坍塌有关。
The importance of small-scale seismic events in enclosed water bodies, which can result in large tsunami waves capable of affecting comprehensive damage over small, geographically-confined areas are generally overlooked, although recognizing the occurrence of such events is a necessary element in adequately assessing the risk of natural hazards at specific locations. Here we present evidence for a probable large localized tsunami that occurred within the Bay of La Paz, Baja California Sur, ~1100 year before present (BP), which resulted in the creation of a shelly ridge at an elevation of ~2 m above mean high water (MHW). This ridge consists of a continuous wedge of poorly mixed marine sands and shells ~50 cm in depth deposited along the entire seaward edge of the lake. The marine shells collected from terrestrial environments around the lake include species from a variety of environments, including offshore species with minimum preferred depths of >13 m. The evidence suggests that this material was likely deposited by a tsunami with a runup of 2–3.6 m above MHW, probably associated with the slumping of an island along the tectonically active eastern edge of the bay.