{"title":"用XRF岩心扫描仪估算混合层海啸沉积物的层界","authors":"Kengo NAKAMURA, Tatsu KUWATANI, Takeshi KOMAI","doi":"10.5026/jgeography.132.403","DOIUrl":null,"url":null,"abstract":"From the perspective of disaster prevention, it is necessary to clarify the distribution and historical frequency of tsunami deposits. However, tsunami deposits are disturbed by earthquakes and tsunamis. Therefore, it is difficult to identify the layers of deposits. Layers deposited during disturbances are dated and grain-size distribution is measured. Using the results of geochemical data and principal component analyses with detailed elemental distributions, stratigraphic boundaries of past tsunami deposit layers and other layers left in the disturbed deposits are estimated. Samples collected with a geo-slicer consist of a 50-60 cm deep disturbed layer deposited by the Great East Japan Earthquake and underlying sand, peat, and marine deposits. 24 elemental distributions in a core measured using Itrax indicate that the disturbed layer is dominated by heavy metals. Changes in principal component analysis scores infer traces of a layer that could not be visually identified in the disturbed layer. Traces of this layer are consistent with traces that are deposits indicated from the isotopic analysis and the grain size distribution. Therefore, even if it is difficult to identify deposits due to disturbances caused by the tsunami, it may be possible to identify unidentified layers and estimate their thicknesses by compressing their dimensions and clarifying elemental relationships.","PeriodicalId":51539,"journal":{"name":"Journal of Geography","volume":"4 1","pages":"0"},"PeriodicalIF":2.6000,"publicationDate":"2023-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"3","resultStr":"{\"title\":\"Estimating Layer Boundaries of Mixed-layer Tsunami Deposits with a XRF Core Scanner\",\"authors\":\"Kengo NAKAMURA, Tatsu KUWATANI, Takeshi KOMAI\",\"doi\":\"10.5026/jgeography.132.403\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"From the perspective of disaster prevention, it is necessary to clarify the distribution and historical frequency of tsunami deposits. However, tsunami deposits are disturbed by earthquakes and tsunamis. Therefore, it is difficult to identify the layers of deposits. Layers deposited during disturbances are dated and grain-size distribution is measured. Using the results of geochemical data and principal component analyses with detailed elemental distributions, stratigraphic boundaries of past tsunami deposit layers and other layers left in the disturbed deposits are estimated. Samples collected with a geo-slicer consist of a 50-60 cm deep disturbed layer deposited by the Great East Japan Earthquake and underlying sand, peat, and marine deposits. 24 elemental distributions in a core measured using Itrax indicate that the disturbed layer is dominated by heavy metals. Changes in principal component analysis scores infer traces of a layer that could not be visually identified in the disturbed layer. Traces of this layer are consistent with traces that are deposits indicated from the isotopic analysis and the grain size distribution. Therefore, even if it is difficult to identify deposits due to disturbances caused by the tsunami, it may be possible to identify unidentified layers and estimate their thicknesses by compressing their dimensions and clarifying elemental relationships.\",\"PeriodicalId\":51539,\"journal\":{\"name\":\"Journal of Geography\",\"volume\":\"4 1\",\"pages\":\"0\"},\"PeriodicalIF\":2.6000,\"publicationDate\":\"2023-10-25\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"3\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Geography\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.5026/jgeography.132.403\",\"RegionNum\":3,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"GEOGRAPHY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Geography","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.5026/jgeography.132.403","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOGRAPHY","Score":null,"Total":0}
Estimating Layer Boundaries of Mixed-layer Tsunami Deposits with a XRF Core Scanner
From the perspective of disaster prevention, it is necessary to clarify the distribution and historical frequency of tsunami deposits. However, tsunami deposits are disturbed by earthquakes and tsunamis. Therefore, it is difficult to identify the layers of deposits. Layers deposited during disturbances are dated and grain-size distribution is measured. Using the results of geochemical data and principal component analyses with detailed elemental distributions, stratigraphic boundaries of past tsunami deposit layers and other layers left in the disturbed deposits are estimated. Samples collected with a geo-slicer consist of a 50-60 cm deep disturbed layer deposited by the Great East Japan Earthquake and underlying sand, peat, and marine deposits. 24 elemental distributions in a core measured using Itrax indicate that the disturbed layer is dominated by heavy metals. Changes in principal component analysis scores infer traces of a layer that could not be visually identified in the disturbed layer. Traces of this layer are consistent with traces that are deposits indicated from the isotopic analysis and the grain size distribution. Therefore, even if it is difficult to identify deposits due to disturbances caused by the tsunami, it may be possible to identify unidentified layers and estimate their thicknesses by compressing their dimensions and clarifying elemental relationships.
期刊介绍:
Journal of Geography is the journal of the National Council for Geographic Education. The Journal of Geography provides a forum to present innovative approaches to geography research, teaching, and learning. The Journal publishes articles on the results of research, instructional approaches, and book reviews.