Search

Dissertation, RWTH Aachen University, 2021; Aachen : RWTH Aachen University 1 Online-Ressource : Illustrationen, Diagramme (2021). = Dissertation, RWTH Aachen University, 2021, Tsunamis as perilous natural hazards were not comprehended and underestimated by humanity for a long time. After several major events in recent decades, tsunami science has come into focus to understand the processes behind them, to mitigate their effects, and to build protective measures. Geological methods have proven to be a promising approach to identify tsunami deposits and expand the knowledge about tsunamis. The sedimentological, micropaleontological and geophysical applications, now considered as standard methods, have helped to advance the progress of science concerning tsunamis. However, the standard proxies encounter some limitations in terms of differentiation of tsunami and storm deposits, reliability for determining total inundation area, and underestimation of impacts. For several years, the aim of tsunami science has been to retrieve new promising proxies and apply them on tsunami deposits. Inorganic geochemistry has made a major contribution to answering outstanding questions related to complete inundation and fine-grained tsunami deposits. The application, however, is problematic due to constraints on persistence and preservation, especially for paleo- and historic tsunami deposits. The emerging and novel application of organic geochemistry has the possibility to fill the knowledge gaps by its advantages, especially with its high preservation and persistence potential. The already frequently used method in the environmental studies refers to natural and anthropogenic substances, which can provide information about (I) the maximum inundation, even beyond the visible sand deposits; (II) the distribution of compounds and sediments by the tsunami; and (III) trace the destruction and pollution caused by modern tsunamis. The doctoral thesis follows the approach of applying organic geochemistry with a multi-proxy analysis to historical tsunamis in El Palmar de Vejer (AD 1755 Lisbon tsunami); evaluating appropriate normalization of the samples for quantitative interpretation; applying new indicator compounds beyond the usual ones already applied at the Aomori coast in Japan (2011 Tohoku-oki tsunami); assessing the distribution of the compounds, as well as locating its potential sources at Misawa Harbor in Northern Japan. Sedimentological, geophysical, inorganic, and organic geochemical methods were carried out to a multi-proxy approach on AD 1755 Lisbon tsunami deposits at El Palmar de Vejer (Spain) to corroborate the potential of organic geochemistry with other methods. In the good sedimentary archive of a floodplain, tsunami sediments were identified on sandy samples. Another potential tsunami layer, consisting of mud, was also detected. Based on the geochemistry, conclusions could be drawn about two successive tsunami waves. Natural organic materials have shown their potential to be suitable for application to historical tsunamis. Anthropogenic organic markers, however, did not show their potential because of low human activity in the vicinity and the subsequent low release of combustion pollutants. At three different locations along the Aomori coastline (Japan), samples from the 2011 Tohoku- oki tsunami and the surrounding strata were collected. The samples were to be used to test new potential organic indicator compounds for suitability and to distinguish tsunami deposits from the non-affected sediments. Firstly, the quantitative evaluation of the samples was questioned as to whether normalization to total organic carbon (TOC) or grain size was necessary. The robust data set confirmed that the TOC normalization already applied provided the better approximation. Indicator compounds used for tsunami discrimination were identified, especially old burden markers and sewage-derived marker were added to the toolbox of tsunami geochemistry. However, n-aldehydes were also evaluated as unsuitable indicators. A follow-up study, with the new indicator compounds already applied, was conducted at Misawa Harbor. Only the 2011 Tohoku-oki tsunami deposits with a larger quantity of samples were analyzed and examined for distribution patterns and emission sources. The results provided a topographically controlled deposition, as well as different emission sources of the pollutants. Some contaminants are point source specific (e.g., petrogenic markers) and others are from diffuse sources (e.g., linear alkylbenzene and old burdens), but all are deposited at the topographically controlled location.The doctoral thesis has shown that organic geochemistry has a high potential for tsunami research and can extend standard methods. In particular, the recognition of additional indicator compounds and the possible application to historical tsunamis is important for comprehension of tsunamis. Another important aspect is the knowledge of the distribution and the emission sources, which must be tested especially at further locations., Published by RWTH Aachen University, Aachen

Dissertation, RWTH Aachen University, 2020; Aachen : RWTH Aachen University 1 Online-Ressource (h, x, 196 Seiten) : Illustrationen, Diagramme, Karten (2021). = Dissertation, RWTH Aachen University, 2020, Foraminiferal assemblages and sediment characteristics on Crete island are examined by quantitative analysis multivariate techniques on drill core and beach sand samples along Crete´s coastal zones. This research aims to reconstruct the environment, bathymetry of recent foraminifera, and sediment composition and determine the relationship between foraminifera distribution and grain size. The methods applied include diversity statistics, cluster analysis (Q and R modes), and PCA (Principal Component Analysis). The species diversity or biodiversity is measured using species richness, the Fisher - α index, Simpson index, Shannon-Wiener index, and the percentage of species dominance. The P/R ratio (the portions of planktic foraminifera in the total foraminifera assemblages) is also used to calculate the bathymetry. In the western area, results of microfossil analysis show a total of 14 common species from a total of 66 species, which are divided into four clusters corresponding to four groups using R and Q modes, respectively: (Ia) Peneroplis pertusus; (Ib) Cibicides pseudolobatulus; (II) Ammonia beccarii; (III) Globigerina bulloides - Globigerinoides ruber. The P/R ratio and PCA result reveals the inner shelf species´ appearance in cluster I and II, the inner to middle shelf of species in cluster II; and outer shelf to upper bathyal species in cluster III.In the southern area, four clusters are defined from cluster analysis results: (IV) Amphistegina lobifera - Amphistegina lessonii; (V) Amphistegina lobifera; (III) Globigerinoides ruber; (VI) Elphidium crispum - Ammonia beccarii. The P/R ratio and PCA results of cluster III indicates species belong to the outer shelf to upper bathyal and semi-pelagic to eupelagic environment while in clusters IV, V and VI present species from the inner shelf environment. In the eastern area four clusters can be distinguished: (Ia) Peneroplis pertusus; (V) Amphistegina lobifera; (VII) Globigerinoides ruber; (VIII) Amphistegina lobifera - Ammonia beccarii - Elphidium crispum. The P/B ratio in cluster I indicates species from the inner shelf to upper bathyal areas, whereas the P/R ratio and PCA of cluster VIII and V and Ia present the inner shelf environment. Finally, seven dominant foraminifera assemblages are defined in the whole study area: Amphistegina lobifera; Peneroplis pertusus; Globigerina bulloides; Globigerinoides ruber; Ammonia beccarii; Elphidium crispum and Cibicides pseudolobatulus. Foraminifera analysis results reveal a high percentage of Globigerinoides ruber and Globigerina bulloides in the inner shelf of the environment´s sediment and the core samples. These species are not well preserved and reworked. PCA, CCA, and cluster analysis show the uncorrelated relationship between coastal species and outer bathyal to bathyal species in their specific. These species work as a proxy for transport from the outer shelf bathyal zone to the coastal area during tsunamis or extreme wave events. The correlation of the most abundant species and specific sediment fractions from all three areas indicates that sediment grain size is the primary factor determining species distribution. In each subarea, a correlation of most species in particular or the most abundant species with one or more sediment fractions is shown by bivariate and multivariate applications. The correlation between sediment components and foraminiferal assemblages by applying quantitative analysis shows a relationship between the foraminifera and sediment composition of the Cretan coastal area, supporting provenance analysis of beach sediments., Published by RWTH Aachen University, Aachen

Dissertation, RWTH Aachen University, 2019; Aachen 1 Online-Ressource (XIX, 195 Seiten) : Illustrationen, Diagramme, Karten (2020). = Dissertation, RWTH Aachen University, 2019, Natural hazards have accompanied humanity throughout history, however, amongst these tsunamis have been the least understood events until relative recent times. Broadcasting itself on the global stage tsunamis got into the center of public and scientific attention after the contemporary devastating events of the 2004 Indian Ocean Tsunami and the 2011 Tohoku-oki Tsunami. Focused research, started in the late 1980s, found its peak in the aftermath of these prominent tsunamis. In the course of tsunami investigations few methods have merit the status as standard proxies in the tsunami identification toolkit. In their broad application in paleo-, historic and modern tsunami surveys, standard sedimentological and paleontological proxies have become almost indispensable assets. This undisputed position, however, is crumbling since the limitations on the (solely) analysis of sandy deposits by these methods potentially contributed to the underestimation of the hazard potential along the Japanese coastline prior to the 2011 Tohoku-oki tsunami. These limitations in line with inevitable analytical progression is a byproduct of every newly introduced study into tsunami research. The newest introduction marks the promising application of organic geochemistry for characterization of tsunamites. Organic geochemistry is commonly used in environmental studies, however, its entry in context with increased numbers of inorganic geochemical studies represents the beginning of a new chapter in tsunami research. This thesis evaluates the limits of standard proxies before assessing the application and limitations of organic geochemical markers, both biomarker and anthropogenic markers. At three field locations, Boca do Rio (Portugal), Kahana Valley (Hawaii) and Sendai Plain (Japan) with varying sedimentological and environmental settings affected by tsunamis of different magnitude and age, standard and organic geochemical proxies are tested and results contrasted. At Boca do Rio a multi-proxy study was conducted not only characterizing the AD 1755 Lisbon tsunami but also lead to the detection of a yet unknown tsunami deposit event, most likely dating to the mid orlate 1st millennium AD. With standard sedimentological, micropaleontological and inorganic geochemical methods we were able to extend the Portuguese tsunami record. Inorganic geochemical proxies are already frequently used to detect marine inundation events, however, certain proxies (e.g., salts) are limited by their low preservation potential. The Hawaiian Islands experienced due to their location in the center of the Pacific Ocean, dozens of tsunamis over the past 200 years. Two complementary studies on the Islands have led to the identification of multiple anomalous sand beds of tsunami origin by standard sedimentological proxies and an organic geochemical characterization of aforementioned with the first successful application of anthropogenic markers. Compounds, such as polycyclic aromatic hydrocarbons, pesticides and organochlorides, were extracted from the sediments and analyzed using gas chromatography-mass spectrometry. Distinct changes in concentration between the tsunami sands and the surrounding background sediment helped in identification. While application in rural areas remains difficult, this presenting the first successful application of organic proxies on tsunami deposits also shows the potential of geochemical markers. Succeeding the positive results of the first application we present a concluding proof-of-concept study for biomarkers and anthropogenic markers. At the Sendai Plain the 2011 Tohoku-oki tsunami inundated the coastal lowland up to 4.5 km inland, causing massive destruction while eroding and redistributing large amounts of soil and sediment. This led to the release and distribution of anthropogenic markers and biomarkers from different sources across the Sendai Plain creating a unique geochemical signature in the tsunami deposits. Their concentrations differed significantly from the pre- and post-tsunami background contamination levels, reflecting the remarkable environmental changes on the Sendai Plain due to the tsunami. In this proof-of-concept study prior research results by Richmond et al. (2012), Szczuciński et al (2012) and Shinozaki et al. (2015) have been positively reproduced by organic geochemical proxies, and even extended by presenting more specific sediment sources due to the high source specificity of the detected compounds. While the application of standard proxies is crucial, the extension of available tools on disposal for tsunami identification is of importance. Organic geochemistry, the newest entry into this toolkit presents great potential in providing additional information on hydrodynamic processes, sediment erosion, transport and deposition, potential (water-)pathways (e.g., marine source, evidence of backwash) associated with tsunamis. Especially as these parameters are site-specific, they can be well-captured by organic markers due to their high source-specificity and good preservation potential. By this doctoral thesis we demonstrate the indisputable usefulness of standard proxies for tsunami investigations and the capabilities of organic geochemical proxies. Latter are presented by utilization on different sedimentary archives to highlight their future potential to close existing knowledge gaps still unanswered by standard proxies., Published by Aachen