The tsunami history of southwest Thailand - Recurrence, magnitude and impact of palaeotsunamis inferred from onshore deposits

The Indian Ocean tsunami (IOT) of December 2004 has uncovered a till then widely unacquainted tsunami risk for the west coast of southern Thailand. To limit loss of life and damage due to potential future events, data about the frequency and magnitude of tsunamis in Thailand over a longer time period is needed. Since modern and historical tsunami recording in the Bay of Bengal is limited to the last 300 years, details about the long-term hazard have to be drawn from geological evidence of prehistoric tsunami flooding by (i) identifying new palaeotsunamis, (ii) dating and (iii) correlating spatially distinct evidence, and (iv) establishing the magnitude and the intensity of these events. For this, sediments from near-shore geoarchives in the coastal areas of Phang-nga province and Phuket (Thailand) have been sampled and analysed sedimentologically (granulometry, geochemistry, mineralogy, fauna, sedimentation modelling) and chronologically (optically stimulated luminescence and radiocarbon dating). Evidence of multiple prehistoric coastal flooding events in the form of allochthonous sand beds was identified in the coastal plain of Ban Bang Sak. The layers are assigned to high-energy events of marine origin, either tsunamis or tropical storms, by means of the sediment characteristics. The distinction between tsunamites and tempestites is mainly based on comparison of the palaeoevent beds with the local deposit of the IOT 2004, which revealed similarities regarding spatial extent and sediment properties. Furthermore, the radiocarbon age of the youngest palaeoevent correlates with contemporaneous tsunami evidence from India and Sumatra. Hence, the youngest event, dated to 500-700 cal BP, is related to a basin-wide tsunami, while several older events that took place between 2000 and 1180 cal BP preliminary are treated as tsunami candidates. Since the application of radiocarbon for dating tsunamites on Phra Thong Island is limited by the scarcity of datable macro-remains and the contamination by young roots, here, the potential of optical dating (OSL) is evaluated by applying the method to a suite of tsunamigenic and littoral deposits for which independent age control is available. Small aliquots of coarse-grained quartz were used for measurements, and processed statistically by means of appropriate age models. Cross-checking with independent radiocarbon data showed good agreement for littoral deposits and only insignificant residuals of less than 40 years for the poorly bleached deposits of the IOT 2004. These results legitimate the use of OSL to determine ages of palaeotsunamis in the same setting. Therefore, the established luminescence procedure was applied as a tool to correlate the spatially distinct sand sheets of prehistoric tsunamis that are preserved in the swales of Phra Thong’s beach-ridge plain. At least three palaeoevents – being 490–550, 925–1035 and 1740–2000 years old – are distinguished and correlated between the swales of Phra Thong (as an indicator for inundation distances), as well as within the Bay of Bengal (as an indicator for the impact areas). For the interpretation of onshore tsunami deposits in terms of magnitude and impact on coastal systems, the boundary conditions at the time of prehistoric tsunami events have to be taken into account. Pre-existing sea-level curves for the Malay-Thai Peninsula postulate a mid-Holocene maximum of 1-5 m above present sea level, whereas the exact timing and magnitude of the Holocene highstand in Thailand remained to be defined. By the use of fixed biological and geomorphological sea-level indicators a Holocene maximum of +2.6 m in the south and +1.5-2.0 m in the north of the study area is assessed for c. 5500 years ago. In addition, Holocene changes of palaeogeography and their influence on local tsunami records are studied. While the patterns of palaeotsunamis recorded on Phra Thong and at Ban Bang Sak can be explained by the onset of back-barrier swamp formation, the existence of only one prehistoric tsunami deposit at Pakarang Cape is in conflict with the persistence of a back-reef lagoon, which provided favourable conditions for preservation over millennia. Although the IOT 2004 had a strong short-term impact on infrastructure, housing, ecosystems and coastal morphology in Thailand, the damaged systems have almost completely recovered after less than 10 years. For prehistoric tsunamis, the long-term impact is assessed based on variations of the sedimentary environments before and after the events. It can be shown that all recorded palaeotsunamis had only insignificant impact on the ecosystems and the geomorphology of Phra Thong Island, Ban Bang Sak and Pakarang Cape. To deduce transport processes and hydrodynamic parameters of tsunami events from the onshore deposits found at Ban Bang Sak, as an estimate of palaeotsunami magnitude, two different ap-proaches are applied. (i) The maximum offshore sediment source is determined using granulometry, geochemistry, mineralogy, and foraminifera of tsunamites and reference samples from various marine and terrestrial environments. (ii) By means of sedimentation modelling, onshore flow velocities and flow depths of the associated tsunami waves are estimated. The approach is evaluated by means of the IOT 2004, for which modelled flow velocities and onshore flow depths, as well as the deduced sediment source are in good agreement with quotations based on survivor videos and post-tsunami field surveys. For the 500-700 year old predecessor with modelled flow velocities and flow depths of 4.1-5.9 m/s and 7.0 m, respectively, a magnitude similar to the IOT 2004 is reconstructed. The deposits of the three tsunami candidates dated to 1180-2000 cal BP partly indicate source areas equal to the IOT 2004, suggesting events of comparable size, and partly indicate a much shallower sediment source, pointing to a storm origin or tsunamis of a lesser magnitude. In conclusion, a recurrence interval of 500-600 years for tsunamis in southwest Thailand is estimated on the basis of sedimentary evidence. Since all tsunamis recorded in Thailand are triggered by mega-ruptures of the Sunda Arc with similar magnitude and geometry as the 2004 earthquake, which have not only local but basin-wide impact, the data from Thailand provide valuable information for the assessment of future tsunami risk in other countries around the northern Indian Ocean, as well

Mehr Infektionsschutz durch Health-Nudging? Eine experimentelle Untersuchung der Wirkung von Nudges auf die Nutzung von Desinfektionsmittelspendern

Die effektive Umsetzung von Hygienemaßnahmen hat in Zeiten der vermehrten Verbreitung von Viren, vor allem in der Grippezeit (in den Wintermonaten) und angesichts der aktuellen COVID-19-Pandemie, an Relevanz gewonnen. Insbesondere im öffentlichen Raum ist es wichtig, Individuen verstärkt zur Nutzung von Desinfektionsmittelspendern zu motivieren, um das Infektionsrisiko zu verringern. Mithilfe eines präregistrierten Experiments wurde im Rahmen der vorliegenden Studie untersucht, ob der Einsatz rein visueller und visuell-informativer Nudges sowie deren parallele Anwendung zu einer Steigerung der Nutzung von Händedesinfektionsmittelspendern in öffentlichen Einrichtungen führt. Die Ergebnisse der Studie deuten darauf hin, dass die eingesetzten Nudges einen positiven Effekt auf die Nutzung von Desinfektionsmittelspendern haben. Insbesondere die zeitgleiche Anwendung der Nudges führte zu einer deutlichen Steigerung der Nutzer*innenzahlen.Given the intermittent flu epidemics (especially in winter) and the recent COVID-19 pandemic, the efficacy of hygiene measures became more relevant. Particularly in public space, it is important to motivate individuals to use hand disinfection dispensers to reduce the infection risk. By means of a preregistered experiment, the present study examines whether the application of mere visual and visual-informative nudges increases the number of users of hand disinfection dispensers. The results indicate that nudges have a positive effect on the use of disinfection dispensers. Notably, the simultaneous application of both nudges led to a distinct increase of the number of users

Approval-Based Apportionment

In the apportionment problem, a fixed number of seats must be distributed among parties in proportion to the number of voters supporting each party. We study a generalization of this setting, in which voters cast approval ballots over parties, such that each voter can support multiple parties. This approval-based apportionment setting generalizes traditional apportionment and is a natural restriction of approval-based multiwinner elections, where approval ballots range over individual candidates. Using techniques from both apportionment and multiwinner elections, we are able to provide representation guarantees that are currently out of reach in the general setting of multiwinner elections: First, we show that core-stable committees are guaranteed to exist and can be found in polynomial time. Second, we demonstrate that extended justified representation is compatible with committee monotonicity

Testing the accuracy of feldspar single grains to date late Holocene cyclone and tsunami deposits

Quartz is the preferred dosimeter for luminescence dating of Holocene sediments as optically stimulated luminescence (OSL) signals reset rapidly upon light exposure, and are stable over time. However, feldspar is required where quartz luminescence properties are inappropriate for dating, as is often the case in geologically young mountain ranges and areas with young volcanism. Here we aim to evaluate the potential of single grain feldspar luminescence dating applied to late Holocene cyclone and tsunami deposits, for which complete signal resetting can a priori not be guaranteed. To address potential problems of feldspar dating of such deposits associated with heterogeneous bleaching, remnant doses and anomalous fading, we use a low-temperature post infrared infrared stimulated luminescence protocol (pIRIR150) on single grains. For most samples, good agreement between fading corrected IR50 and non-fading corrected pIRIR150 ages is observed. Both feldspar ages generally also show good agreement with age control provided by historical data and quartz luminescence ages. pIRIR150 remnant ages in modern analogue samples are shown to be 150, IR50 and quartz ages, indicates that a significant number of grains must have experienced relatively complete signal resetting during or immediately prior to transport, as the three signals are known to bleach at different rates. Since light exposure during the event is expected to be limited, we deduce that a significant portion of the grains in the cyclone and tsunami deposits was already bleached prior to the event of interest. These well-bleached grains were likely eroded at the beach, while other grains with larger remnant ages probably originate from the shallow subtidal, coastal barriers or even further inland sources. Additional signal resetting during storm and tsunami transport is indicated by slightly younger quartz than feldspar ages for grains with incomplete pre-transport resetting that were eroded at the Holocene coastal barrier.</p

The environs of Elaia (NW Turkey) – Sea-level fluctuations, vegetation history and microfaunal record

-

Approval-based apportionment

In the apportionment problem, a fixed number of seats must be distributed among parties in proportion to the number of voters supporting each party. We study a generalization of this setting, in which voters can support multiple parties by casting approval ballots. This approval-based apportionment setting generalizes traditional apportionment and is a natural restriction of approval-based multiwinner elections, where approval ballots range over individual candidates instead of parties. Using techniques from both apportionment and multiwinner elections, we identify rules that generalize the D’Hondt apportionment method and that satisfy strong axioms which are generalizations of properties commonly studied in the apportionment literature. In fact, the rules we discuss provide representation guarantees that are currently out of reach in the general setting of multiwinner elections: First, we show that core-stable committees are guaranteed to exist and can be found in polynomial time. Second, we demonstrate that extended justified representation is compatible with committee monotonicity (also known as house monotonicity)

A 68 ka precipitation record from the hyperarid core of the Atacama Desert in northern Chile

[Abstract] The Atacama Desert in northern Chile is one of the driest deserts on Earth. Hyperaridity persists at least since the Miocene and was punctuated by pluvial phases. However, very little is known about the timing, regional spread and intensities of precipitation changes. Here, we present a new precipitation record from a sedimentary sequence recovered in a tectonically blocked endorheic basin that is located in the hyperarid core of the Atacama Desert. The chronostratigraphic framework of the record is given by a multi-disciplinary dating approach, suggesting an age of ca. 68 ka BP for the core base. The sequence consists of three sediment types, whose sedimentological and geochemical characteristics suggest different depositional processes that reflect different degrees in humidity. First, particularly fine-grained sediments with high clastic but low calcium sulfate and carbonate contents reflect a particularly dry climate with only sporadic precipitation events and fluvial supply via channel systems. Second, more coarse-grained sediments with lower clastic and higher calcium sulfate and carbonate contents reflect more moist conditions with stronger precipitation events that lead to fluvial activity not restricted to the channels but involving the slopes and plains in the catchment. Third, normally graded layers with an equally high proportion of calcium sulfate and carbonate reflect occasional high-precipitation events that caused sediment supply also from most distant parts of the catchment via severe flash floods. The sedimentary succession suggests that precipitation changes took place on orbital but also on millennial time scales. Rather moist periods occurred during most of MIS 2, several shorter periods within MIS 3 and parts of MIS 4. Comparison of the findings from the Huara record with selected climate records from continental and marine sites in South America suggests a strong precipitation heterogeneity across the Atacama. This heterogeneity is caused by pronounced differences in the dominating climate patterns and a shift from predominant summer rain in the north to winter rain in the south. Precipitation supply to the Huara clay plan is controlled by the atmospheric circulation rather than the surface temperature of the adjacent ocean

The Use of Spinning-Disk Confocal Microscopy for the Intravital Analysis of Platelet Dynamics in Response to Systemic and Local Inflammation

Platelets are central players in inflammation and are an important component of the innate immune response. The ability to visualize platelets within the live host is essential to understanding their role in these processes. Past approaches have involved adoptive transfer of labelled platelets, non-specific dyes, or the use of fluorescent antibodies to tag platelets in vivo. Often, these techniques result in either the activation of the platelet, or blockade of specific platelet receptors. In this report, we describe two new methods for intravital visualization of platelet biology, intravenous administration of labelled anti-CD49b, which labels all platelets, and CD41-YFP transgenic mice, in which a percentage of platelets express YFP. Both approaches label endogenous platelets and allow for their visualization using spinning-disk confocal fluorescent microscopy. Following LPS-induced inflammation, we were able to measure a significant increase in both the number and size of platelet aggregates observed within the vasculature of a number of different tissues. Real-time observation of these platelet aggregates reveals them to be large, dynamic structures that are continually expanding and sloughing-off into circulation. Using these techniques, we describe for the first time, platelet recruitment to, and behaviour within numerous tissues of the mouse, both under control conditions and following LPS induced inflammation

Lipid metabolic perturbation is an early-onset phenotype in adult spinster mutants: a Drosophila model for lysosomal storage disorders

Intracellular accumulation of lipids and swollen dysfunctional lysosomes are linked to several neurodegenerative diseases, including lysosomal storage disorders (LSD). Detailed characterization of lipid metabolic changes in relation to the onset and progression of neurodegeneration is currently missing. We systematically analyzed lipid perturbations in spinster (spin) mutants, a Drosophila model of LSD-like neurodegeneration. Our results highlight an imbalance in brain ceramide and sphingosine in the early stages of neurodegeneration, preceding the accumulation of endomembranous structures, manifestation of altered behavior, and buildup of lipofuscin. Manipulating levels of ceramidase and altering these lipids in spin mutants allowed us to conclude that ceramide homeostasis is the driving force in disease progression and is integral to spin function in the adult nervous system. We identified 29 novel physical interaction partners of Spin and focused on the lipid carrier protein, Lipophorin (Lpp). A subset of Lpp and Spin colocalize in the brain and within organs specialized for lipid metabolism (fat bodies and oenocytes). Reduced Lpp protein was observed in spin mutant tissues. Finally, increased levels of lipid metabolites produced by oenocytes in spin mutants allude to a functional interaction between Spin and Lpp, underscoring the systemic nature of lipid perturbation in LSD