New Zealand's most easterly palaeotsunami deposit confirms evidence for major trans-Pacific event
New Zealand's most easterly palaeotsunami deposit confirms evidence for major trans-Pacific event
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新西兰最东端的古海啸沉积物证实了重大跨太平洋事件的证据
DOI：
10.1016/j.margeo.2018.08.001
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发表时间：
2018
期刊：
影响因子：
2.9
通讯作者：
King D.N.
中科院分区：
文献类型：
--
作者：
Goff J.;Goto K.;Chague C.;Watanabe M.;Gadd P.S.;King D.N.
使用沉积、地球化学、地貌、放射性碳和数值模拟数据来检查新西兰查塔姆岛大川角巨石散落的性质、范围和年龄。在内陆 800m 处发现了重达 98 吨的巨石，这些巨石包括位于全新世中期高位风暴脊两侧的向陆和向海群，其年代可追溯至 4840-4810calBP 左右。向陆的巨石散布与神秘的粗砂/砾石层有关，该层向内陆延伸至 1100m，其年代可追溯到约 3500-4500calBP。数值模拟表明，虽然主要位于查塔姆岛片岩海岸平台上的向海巨石可能是被风暴或海啸波所取代，但那些位于全新世中期风暴脊向陆的巨石最有可能被迁移。 因海啸。据报道，新西兰大陆、澳大利亚、西南太平洋和更广泛的太平洋地区发现了几处近乎同期的古海啸沉积物。如果其中一些或全部与同一个盆地范围的古海啸有关，那么它似乎可能是全新世最大的太平洋古海啸之一。对历史和数值模型数据的分析表明，最有可能的候选者来自智利北部地震间隙内，早期证据表明大型古地震和古海啸事件可能发生在距今 4000 年左右。如果正确的话，这对于评估智利北部地震间隙的最大可能震级地震及其产生的海啸规模具有重要意义。
Sedimentary, geochemical, geomorphological, radiocarbon and numerical modelling data were used to examine the nature, extent and age of a boulder scatter at Okawa Point, Chatham Island, New Zealand. Boulders up to 98 t were traced around 800 m inland and comprised both a landward and seaward grouping on either side of a mid-Holocene high-stand storm ridge dated to around 4840–4810 cal BP. The landward boulder scatter was linked with an enigmatic coarse sand/gravel layer that extends up to 1100 m inland and has been dated to around 3500–4500 cal BP.Numerical modelling indicated that while the seaward boulders that mainly rest upon the Chatham Island Schist shore platform could have been emplaced by either storm or tsunami waves, those landward of the mid-Holocene storm ridge were most probably transported by a tsunami. There are several near-contemporaneous palaeotsunami deposits reported from mainland New Zealand, Australia, SW Pacific and the wider Pacific region. If some or all of these are associated with the same basin-wide palaeotsunami then it appears likely to have been one of the largest Holocene Pacific palaeotsunamis. An analysis of historical and numerically modelled data suggests that the most likely candidate is from within the northern Chile seismic gap, with early evidence suggesting that a large palaeoseismic and palaeotsunami event may have occurred around 4000 yr BP. If correct, this has important implications for assessing the largest possible magnitude earthquakes in the northern Chile seismic gap and the size of the tsunamis they generate.