Archaeological remains as sea level change markers: A review

The Mediterranean Sea constitutes a unique basin from an historical and archaeological point of view, as it has been a privileged way of communication for thousands of years for the people that dwelled on its shores. Their passage has left many traces on the seabeds in the areas where the ancient commercial routes passed, and remains of structures where moorings, havens or dwellings existed. Some of these structures, nowadays submerged, offer interesting indications aiding the reconstruction of the ancient coastlines. This contribution aims to examine recent work in coastal geo-archaeology, targeting both (1) gathering and discussion of the data, particularly those pertaining to the Italian coasts; and (2) commentary on the methodological debate and verification of the possibility of a protocol that may contain unequivocal referring elements.To investigate the archaeological evidence currently underwater because of the relative sea level variations (harbour infrastructures, fishponds, villae maritimae, caves – nymphaei, private or public buildings or town quarters, pre- and protohistorical villages, quarries, caves, etc.), a clear and more coherent methodological assumption may be needed. The archaeological interpretation must initially establish the maritime and/or harbour nature and vocation of the site, determine its typology and specific usage, analyze the elements of its building techniques (that reveal themselves as meaningful markers of height or depth at the time of building) and its “functional” elements (the measure of the emerged part with respect to the average sea level), and point out the time of construction, its chronological range of usage/frequentation, the dynamics of its abandonment/destruction/obliteration.The evaluation of both the height and functional depth to the mean sea level depends on the typology of the archaeological evidence, its use and the local tide amplitudes. The surface of a pier surely has a functional elevation different from that of a haulage area or a platea or a pavement.     

Seismic swarms, fault plane solutions, and stress tensors for S?o Miguel Island central region (Azores)

The central region of S?o Miguel Island is one of the most seismically active areas of the Azores archipelago. A revised analysis of the seismicity distribution at this region has, for the first time, shown that the seismicity is clustered in two distinct areas: the area around Fogo Volcano (Fogo) and the area around Congro maar (Congro), with each area having a highly localized swarm activity. From a total of about 15,000 events in the period from 2002 to 2010, 78 best located events were selected to make fault plane solutions using P-wave polarities and amplitude ratios. This set of fault plane solutions, and another six subsets derived from it, were inverted for the best fitting stress tensor. The stress tensor using all the 78 fault plane solutions is characterized by a subhorizontal ??1 striking WNW-ESE and a ??3 striking NNE-SSW, consistent with the regional stress field for this region. A similar result, using only the fault plane solutions located in the Fogo area, was obtained. On the other hand, for the Congro area, a local stress field seems to be superimposed on the regional field: subhorizontal ??3, striking NNE-SSW, and a near-vertical ??1. The same stress regime persists in the first 5?km depth, probably related to the upwelling of thermal fluids. The rising fluids generate horizontal extension at shallow depths, which favour the opening of cracks and the circulation and ascension of hydrothermal fluids. The stress regime deeper than 5?km is more uncertain; however, it is indicative of a compressional regime. Thus, it can be conclude that the smaller Fogo area appears to be dominated by the normal regional stress field while the high active Congro area seems to have a different, highly heterogeneous stress field dominated by local conditions.     

A simple non‐linear analytical relationship between aerosol accumulation number and sub‐micron volume, explaining their observed ratio in the clean and polluted marine boundary layer

We propose an analytical expression for the relation between aerosol accumulation number and sub‐micron volume over the marine boundary layer (MBL), based on a simple balance equation. By providing appropriate source and sink terms which account for entrainment, coagulation, in‐cloud scavenging and condensational growth, the model is able to reproduce the observed ratio between MBL particles larger than 80 nm diameter (as a proxy for accumulation mode number) and submicron aerosol volume, from freshly polluted to background conditions. Entrainment and coagulation are essential in predicting the observed ratio. Budget and lifetime calculations show that, due to relatively low source rates of oceanic non‐sea‐salt‐sulfate and sea‐salt, the anthropogenic signature in aerosol volume remains significant even after 8 days of MBL transport.     

Multiwavelength observations of blazars: a summary

Because of their broad-band nature, multiwavelength observations of blazars are crucial to constrain the emission mechanisms, structure, and physical quantities of the inner jet on parsec and sub-parsec scales. Here I briefly review selected multiwavelength observations of blazars with a particular emphasis on sources detected at GeV and TeV gamma-rays. Their properties are discussed in the frame of the blazar “luminosity sequence”.     

The role of cryptogams in runoff and erosion control on bariland in the Nepal Middle Hills of the Southern Himalaya

Cryptogams are communities of non-vascular plants that live on the soil surface. Numerous functions have been attributed to these crusts, including changes in soil fertility and nutrient status, soil hydrology and soil erosion. Most significant for this paper is the reported benefit of cryptogams in reducing soil erosion by water in semi-arid areas. However, to date there have been few attempts to understand the soil conservation value of cryptogams in subsistence agricultural systems or in humid mountain environments. This paper investigates the potential of cryptogams in soil erosion by water on agricultural hillslope terraces (bariland) in the Nepal Middle Hills of the southern monsoonal Himalaya. The research is significant because the loss of fertile topsoil is considered by some to be the biggest threat to the livelihoods of subsistence farmers in the area in the medium and long term. The current study was conducted in the field between two of the weeding events that take place under maize cover, grown in the traditional manner. Three groundcover types which represented (i) maize only (types A), (ii) maize and weed cover (types B), and (iii) maize and cryptogam cover (types C) were monitored utilizing multiple microerosion plots. Measurements of runoff and soil loss data were collected sequentially on a storm-by-storm basis throughout the monitored period from 24 July 1997 to 29 August 1997. Measurements of infiltration rates were also taken on each of the groundcover types at selected times. Results collected from the erosion plots demonstrate that runoff and soil losses over distances of <2 m can be significantly reduced by up to 50 per cent with cryptogam cover, compared to maize-only canopies. Mean runoff for all storm events sampled from plot types A, B and C were 3·4 l m⁻², 1·6 l m⁻² and 1·5 l m⁻² respectively. For soil loss, the results were 21·7 g m⁻², 11·3 g m⁻² and 10·2 g m⁻² respectively. Therefore, cryptogams would appear to offer a similar degree of protection to the soil surface from runoff and raindrop erosion, to that afforded by weed cover. Weed and cryptogam covers protect the soil surface from rainfall kinetic energies and work to preserve surface microtopographies, depressional storage and surface water detention. Terminal infiltration rates taken at the end of the monitored period showed that well developed maize- and cryptogam-covered soil surfaces (types C) have a mean terminal infiltration rate of 35·0 mm h⁻¹ compared to 44·5 mm h⁻¹ for comparable maize- and weed-covered soil surfaces (types B), and 15·5 mm h⁻¹ for maize-only soil surfaces (types A). These results show that cryptogams and weeds also have relatively higher infiltration rates than comparable maize-only covered plots, devoid of groundcover. The findings in this study may have implications for traditional weed management practices used by local hill farmers, which often destroy cryptogam soil coatings two to three times during the maize growing period. However, further work needs to be done to ascertain farmers' understandings of cryptogams. It is hoped that conservationists will benefit from incorporating cryptogams into the design of future soil erosion studies relating to development programmes. Copyright © 2001 John Wiley & Sons, Ltd.     

Extension of the CSM‐FEMA440 to plan‐asymmetric real building structures

The capacity spectrum method (CSM) has established itself as one of the most used Nonlinear Static Procedures for the seismic assessment of structures, since its introduction in 1975, when it was first presented by Freeman. More recently, this procedure was implemented in the ATC40 guidelines and lately improved in the FEMA‐440 report. The first step of work addressed by this paper relates to the comparison between the two features of the CSM. In the second part, an extension of the FEMA‐440CSM version is proposed for plan‐asymmetric real RC building structures. The case studies under analysis are the SPEAR building—an irregular 3D structure representing typical old three‐storey buildings in the Mediterranean region, from the early 1970s—and two real Turkish buildings with five and eight storeys. The CSM‐ATC40, the CSM‐FEMA440 and the proposed extended CSM‐FEMA440 method are applied and the results obtained duly compared with nonlinear dynamicit timehistory analyses. For the latter, semi‐artificial ground motions are used to define the seismic action. Copyright © 2010 John Wiley & Sons, Ltd.     

New high‐resolution age data from the Ediacaran–Cambrian boundary indicate rapid,ecologically driven onset of the Cambrian explosion

The replacement of the late Precambrian Ediacaran biota by morphologically disparate animals at the beginning of the Phanerozoic was a key event in the history of life on Earth, the mechanisms and the time‐scales of which are not entirely understood. A composite section in Namibia providing biostratigraphic and chemostratigraphic data bracketed by radiometric dating constrains the Ediacaran–Cambrian boundary to 538.6–538.8 Ma, more than 2 Ma younger than previously assumed. The U–Pb‐CA‐ID TIMS zircon ages demonstrate an ultrashort time frame for the LAD of the Ediacaran biota to the FAD of a complex, burrowing Phanerozoic biota represented by trace fossils to a 410 ka time window of 538.99 ± 0.21 Ma to 538.58 ± 0.19 Ma. The extremely short duration of the faunal transition from Ediacaran to Cambrian biota within less than 410 ka supports models of ecological cascades that followed the evolutionary breakthrough of increased mobility at the beginning of the Phanerozoic.     

The Italian strong motion network

The Italian Strong Motion Network is a permanent monitoring system run by the Italian national emergency management department (Dipartimento della Protezione Civile, DPC). The network is known as RAN (Rete Accelerometrica Nazionale). An extensive project for updating and improving the technology of RAN instruments as well as the number of recording points was performed in the last 10 years. A wide site selection survey was carried out from eastern Sicily along the Italian peninsula, covering high seismic risk areas. The recording station density and the choice of high-quality digital strong motion instruments ensure reliability of the RAN network in the long-term. At the end of 2008, the free field sites selection and instruments installation, planned in the project, were quite completed. In planning and drawing the new RAN, special attention has been devoted to the robustness of the transmission systems, and to the distribution of new stations in order to ensure plenty of data during a seismic emergency. We spent special care both in the estimation of the RAN site responses and in the diffusion of the strong motion data. In order to better identify damaged earthquake areas, improved ground motion parameters need to be set. Such parameters will also assist future progress for engineering seismic design techniques as well as disaster mitigation.