Dominik Brill

Shift of large-scale atmospheric systems over Europe during late MIS 3 and implications for Modern Human dispersal

Understanding the past dynamics of large-scale atmospheric systems is crucial for our knowledge of the palaeoclimate conditions in Europe. Southeastern Europe currently lies at the border between Atlantic, Mediterranean, and continental climate zones. Past changes in the relative influence of associated atmospheric systems must have been recorded in the region’s palaeoarchives. By comparing high-resolution grain-size, environmental magnetic and geochemical data from two loess-palaeosol sequences in the Lower Danube Basin with other Eurasian palaeorecords, we reconstructed past climatic patterns over Southeastern Europe and the related interaction of the prevailing large-scale circulation modes over Europe, especially during late Marine Isotope Stage 3 (40,000–27,000 years ago). We demonstrate that during this time interval, the intensification of the Siberian High had a crucial influence on European climate causing the more continental conditions over major parts of Europe, and a southwards shift of the Westerlies. Such a climatic and environmental change, combined with the Campanian Ignimbrite/Y-5 volcanic eruption, may have driven the Anatomically Modern Human dispersal towards Central and Western Europe, pointing to a corridor over the Eastern European Plain as an important pathway in their dispersal.

Holocene sea levels along the Andaman Sea coast of Thailand

For the Malay-Thai Peninsula several sea-level curves for the younger Holocene, based on field evidence as well as on hydro-isostatic modelling of a far-field site, have been published. The general assumption is a rapid rise to a mid-Holocene maximum up to +5 m above present sea level, followed by a constant or oscillating regression. However, from the Andaman Sea coast of Thailand, which was affected by the 2004 tsunami, only isolated observations are available regarding Holocene sea levels. Thus, the timing and magnitude of the Holocene highstand as well as the course of the regression remain to be defined. As several palaeotsunamis could be detected in the meantime it is important to know the related sea levels as exactly as possible to judge the energy, inundation width and potential wave height of these events. Therefore, fixed biological indicators from the rocky coasts of the Phang-nga Bay and Phuket, as well as morphological indicators from beach-ridge and swale sequences along the exposed west coast (Ko Phra Thong) were studied, to gain information about the Holocene sea-level development in this region. While oyster and coral data from the Phang-nga Bay and Phuket document a Holocene maximum of +2.6 m at 5700 cal. BP, the ridge crests and swale bases in the northwest of the study area point to maximum heights of +1.5–2.0 m above the present level around 5300 years ago. During the last 3000 years, to when the largest part of the Holocene palaeotsunami deposits from Thailand was dated, relative sea levels (RSL) in both areas did not exceed +1.5 m.

Coastal hazards from tropical cyclones and extratropical winter storms based on holocene storm chronologies

Aware of past and future climate changes, the question arose whether modern instrumental data adequately reflect the chronology of tropical cyclones and extratropical winter storms for the period of the present eustatic sea level highstand (approx. the past 6,000 years). For pre-instrumental times, geological and sedimentological methods have been applied at geo- and bioarchives such as coastal marshes, lagoons, washover features or beach ridges, showing a frequency of strong cyclones roughly every 100–300 years, which is in contrast to the high number of major cyclones recorded recently. Many of these palaeotempestological records are discontinuous or contain hiatuses and it may be difficult to evaluate whether these sections of the record represent quiet phases without major cyclones or simply erosion or fluctuations in the ability of an archive to record the signature of cyclones. Manifold questions are still unanswered: as the potential number of former cyclones may be stored in landforms and sediments, how can the intensity of these cyclones be identified? Is the crest height of beach ridges a good indicator for storm surge heights, air pressure, and cyclone categories? This paper reviews important achievements in palaeotempestology and discusses open questions of cyclone distribution, frequency and energy (i.e., hazard potential) in the last few decades and reconstructions of these parameters back into Mid-Holocene times.

Sediment Transport and Hydrodynamic Parameters of Tsunami Waves Recorded in Onshore Geoarchives

ABSTRACT Brill, D.; Pint, A.; Jankaew, K.; Frenzel, P.; Schwarzer, K.; Vött, A., and Brückner, H., 2014. Sediment transport and hydrodynamic parameters of tsunami waves recorded in onshore geoarchives. In regions with a short historical tsunami record, the assessment of long-term tsunami risk strongly depends on geological evidence of prehistoric events. Whereas dating tsunami deposits is already well established, magnitude assessment based on remaining sedimentary structures is still a major challenge. In this study, two approaches were applied to deduce transport processes and hydrodynamic parameters of tsunami events from onshore deposits found in the coastal plain of Ban Bang Sak, SW Thailand: (1) The maximum offshore sediment source was determined using granulometry, geochemistry, mineralogy and foraminifera of the tsunamites, and reference samples from various marine and terrestrial environments, and (2) the onshore flow velocities and flow depths of associated tsunami waves were estimated by means of sedimentation modelling. In the case of the Indian Ocean tsunami (IOT) of 2004, modelled flow velocities of 3.7 to 4.9 m/s, modelled onshore flow depths of up to 5.5 m, and a sediment source from offshore areas shallower than a 45-m water depth—including littoral sediments transported as bedload and suspended load from the shallow subtidal zone—are in agreement with quotations based on survivor videos and posttsunami surveys. For a 500- to 700-year-old predecessor, comparable flow velocities and flow depths of 4.1 to 5.9 m/s and 4.0 to 7.5 m, respectively, were modelled, indicating a similar magnitude as the IOT 2004. Comparable values of maximum transport distance and depth of wave erosion were also found. In the case of three older tsunami candidates, dated to 1180 to 2000 cal BP, the deposits indicate partly similar source areas with water depths of less than 45 m and partly shallower source areas restricted solely to the beach. Whereas the former tsunamis are interpreted as events similar to 2004, the latter are more likely storms or tsunamis of a lower magnitude.

Life and death after super typhoon Haiyan

Super typhoon Haiyan, packing sustained winds >300 kph, wrought immense damage on the Philippines in November 2013. Haiyan displaced large boulders in some areas (Engel et al. 2014) and generated an estimated 5 m surge in the Sagay Marine Reserve (10 58¢57.58†N, 123 27¢50.00†E), central Philippines. Immediately after, a coral boulder and rubble ridge several hundred meters long was exposed at low tide on Carbin Reef within the reserve (Fig. 1a). It was either newly established or heightened by the typhoon, but the presence of at least two different depositional units of rubble suggests the latter may be more likely. We present an exhibition of extremes: a heavily damaged subtidal reef area (Fig. 1b) and a largely untouched intertidal coral community (Fig. 1c) separated only by the 20 m-wide ridge. On Carbin’s western slope, the typhoon displaced boulders, sheared stands of Heliopora, and overturned massive colonies down to 10 m. Landwards of the ridge, in the shallow intertidal, many branching acroporids and massive faviids and poritids remained alive and structurally intact, consistent with observations and model predictions of Hongo et al. (2012). Haiyan maystill take its tollhere, however.ByFebruary 2014, partial mortality was evident on the tips of some branching acroporids where they remain above water at low tide. Future surveys will document if the newly established or significantly heightened ridge wrought physical/ hydrological changes that could cause delayed mortality (HarmelinVivien 1994). However, the observable immediate effects of super typhoon Haiyan on Carbin demonstrate that even a category five storm is not a universal death sentence for corals in shallow habitats. Local geomorphology, exposure, and sediment dynamics merit consideration in assessing storm vulnerability, even in the shallowest of reef areas.