New radiolarian biostratigraphic age constraints on Middle Triassic basalts and radiolarites from the Inner Hellenides (Northern Pindos and Othris Mountains, Northern Greece) and their implications for the geodynamic evolution of the early Mesozoic Neotethys

The Avdella Mélange in the northern Pindos Mountains and its equivalent formation, the Loggitsion Unit in the Othris Mountains expose early Mesozoic (Mid-Late Triassic) oceanic fragments beneath the Western Greek Ophiolite Belt of the Inner Hellenides, Northern Greece. The mélange consists of locally interfingering blocks and slices of ribbon radiolarite, radiolarian chert and pillow basalt and is usually overthrust by Jurassic ophiolites. New Middle and Upper Triassic radiolarian biostratigraphic data are presented from radiolarites and basalt-radiolarite sequences within mélange blocks. Pillow basalts associated with the radiolarites provide clues to the opening of the Neotethyan ocean basin. The radiolarians indicate a Middle Triassic age (latest Anisian, probably early Illyrian), which is documented for the first time in the northern Pindos Mountains. The new radiolarian biostratigraphic data suggest that rift-type basalt volcanism already began in pre-Ladinian time (late Scythian?—Anisian). These basalts were then overlain by Upper Anisian to Carnian (?Norian) radiolarites.     

Sliding element simulating the response of slip surfaces and its application for the prediction of earthquake-induced landslide movement using one-dimensional dynamic analyses

Landslides - Earthquake-induced landslides involve excessive movement of slopes, usually along slip surfaces. This seismic movement of slopes may depend crucially on (a) the soil response along the...     

Microseismicity and faulting geometry in the Gulf of Corinth (Greece)

During the summer of 1993, a network of seismological stations was installed over a period of 7 weeks around the eastern Gulf of Corinth where a sequence of strong earthquakes occurred during 1981. Seismicity lies between the Alepohori fault dipping north and the Kaparelli fault dipping south and is related to both of these antithetic faults. Focal mechanisms show normal faulting with the active fault plane dipping at about 45° for both faults. The aftershocks of the 1981 earthquake sequence recorded by King et al . (1985 ) were processed again and show similar results. In contrast, the observations collected near the western end of the Gulf of Corinth during an experiment conducted in 1991 ( Rigo et al . 1996 ), and during the aftershock studies of the 1992 Galaxidi and the 1995 Aigion earthquakes ( Hatzfeld et al . 1996 ; Bernard et al . 1997 ) show seismicity dipping at a very low angle (about 15°) northwards and normal faulting mechanisms with the active fault plane dipping northwards at about 30°. We suggest that the 8–12 km deep seismicity in the west is probably related to the seismic–aseismic transition and not to a possible almost horizontal active fault dipping north as previously proposed. The difference in the seismicity and focal mechanisms between east and west of the Gulf could be related to the difference in the recent extension rate between the western Gulf of Corinth and the eastern Gulf of Corinth, which rotated the faults dipping originally at 45° (as in the east of the Gulf) to 30° (as in the west of the Gulf).     

First evidence for the Cenomanian–Turonian oceanic anoxic event (OAE2, ‘Bonarelli’ event) from the Ionian Zone,western continental Greece

Integrated biostratigraphic (planktonic foraminifera, calcareous nannofossils), chemostratigraphic (bulk C and O isotopes) and compound-specific organic geochemical studies of a mid-Cretaceous pelagic carbonate—black shale succession of the Ionian Zone (western Greece), provide the first evidence for the Cenomanian–Turonian oceanic anoxic event (OAE2, ‘Bonarelli’ event) in mainland Greece. The event is manifested by the occurrence of a relatively thin (35 cm), yet exceptionally organic carbon-rich (44.5 wt% TOC), carbonate-free black shale, near the Cenomanian–Turonian boundary within the Vigla limestone formation (Berriasian–Turonian). Compared to the ‘Bonarelli’ black-shale interval from the type locality of OAE2 in Marche–Umbria, Italy, this black shale exhibits greatly reduced stratigraphic thickness, coupled with a considerable relative enrichment in TOC. Isotopically, enriched δ¹³C values for both bulk organic matter (−22.2‰) and specific organic compounds are up to 5‰ higher than those of underlying organic-rich strata of the Aptian-lower Albian Vigla Shale member, and thus compare very well with similar values of Cenomanian–Turonian black shale occurrences elsewhere. The relative predominance of bacterial hopanoids in the saturated, apolar lipid fraction of the OAE2 black shale of the Ionian Zone supports recent findings suggesting the abundance of N₂-fixing cyanobacteria in Cretaceous oceans during the Cenomanian–Turonian and early Aptian oceanic anoxic events.     

Permeability in flysch �� Distribution decrease with depth and grout curtains under dams

A considerable number of in situ permeability tests in flysch are processed to a depth of 120m with a good spatial distribution. The distribution of permeability values for the different litho-types of this formation, their comparison and their decrease with depth is discussed. The depth where a permeability of 3 to 5×10-7m/sec can be retained (the limit of a reasonable grouting under a high dam) may be twofold if the geological history of the formation could not contain a compressional tectonic process. This depth may reach 100m in some cases. The differences in the mean values of permeability among the various litho-types are minor, while the presence of siltstones, always present although with varied participation, dramatically controls the global permeability.     

Probabilistic spatial risk assessment of heat impacts and adaptations for London

High temperatures and heatwaves can cause large societal impacts by increasing health risks, mortality rates, and personal discomfort. These impacts are exacerbated in cities because of the Urban Heat Island (UHI) effect, and the high and increasing concentrations of people, assets and economic activities. Risks from high temperatures are now widely recognised but motivation and implementation of proportionate policy responses is inhibited by inadequate quantification of the benefits of adaptation options, and associated uncertainties. This study utilises high spatial resolution probabilistic projections of urban temperatures along with projections of demographic change, to provide a probabilistic risk assessment of heat impacts on urban society. The study focuses on Greater London and the surrounding region, assessing mortality risk, thermal discomfort in residential buildings, and adaptation options within an integrated framework. Climate change is projected to increase future heat-related mortality and residential discomfort. However, adjusting the temperature response function by 1–2 °C, to simulate adaptation and acclimatisation, reduced annual heat related mortality by 32–69 % across the scenarios tested, relative to a no adaptation scenario. Similar benefits of adaptation were seen for residential discomfort. The study also highlights additional benefits in terms of reduced mortality and residential discomfort that mitigating the urban heat island, by reducing albedo and anthropogenic heat emissions, could have.     

Brittle-Ductile Transition and Hoek–Brown mi Constant of Low-Porosity Carbonate Rocks

Geotechnical and Geological Engineering - The mechanical behavior of low porosity carbonate rocks is investigated by a series of conventional triaxial compression tests performed at room...     

Umbrella Arch Nomenclature and Selection Methodology for Temporary Support Systems for the Design and Construction of Tunnels

This paper argues that there is a requirement for standardized nomenclature and a selection methodology for a particular class of temporary support. The authors have chosen the term Umbrella Arch (UA) to define the method of support that acts as pre-support that is installed during the first pass of the excavation around and above the crown of the tunnel face. The UA supports the rock mass and the tunnel face predominately by transferring loading longitudinally through the interaction of the support and surrounding ground condition. There are three categories of UA. Categorization depends on the type of support element used. These elements include: (1) Spiles; (2) Forepoles; and (3) Grouted. These categories can be further divided into 11 sub-categories quantified by the amount of grout utilized in the installation. The sub-categories are justified by the employment of each sub-category within a support selection methodology for an UA; this was created by the authors based on experience and through a comprehensive literature search that included published papers as well as design reports. The collection of publications has resulted in 141 permutations of different temporary tunnel support in varying weak and difficult geological condition. The UA support selection methodology was created to aid tunnel designers in these conditions with the basic concepts for the appropriate selection process for an UA. Furthermore, the authors quantified the support selection methodology through the employment of other pre-existing design charts and empirical evidence to create a new design tool, the UA selection chart. Overall, this paper hopes to achieve the creation of an international standard with respect to UA and UA support element nomenclature and a better understanding for the selection of a particular UA sub-category.