Masi, Alessia

This study aims to understand the relationship between the palaeoenvironmental evolution of the southern margin of the Salpi lagoon (Tavoliere coastal plain, Apulia, Italy) and the development of settlements on its shores during the last part of the Holocene (Late Northgrippian to Late Meghalayan) to complement recent archaeological investigations at the site of pre-Roman Salpia Vetus, Roman Salapia and Medieval Salpi. Micropalaeontological, palynological, and sedimentological analyses were conducted on a total of ten drilled cores, revealing local and regional events. Facies and micropalaeontological analyses show that the lagoon was partially connected to the sea between 6.2 ka BP and 3.1 ka BP. Between 3.1 ka BP and 2.4 ka BP, the area was characterised by marshes and swamps with restricted brackish lagoon conditions and permanent freshwater input. After 2.4 ka BP, the continuous freshwater influx from the major rivers of the coastal plain determined the progradation of the floodplain and the closure of the lagoon, with the formation of the two coastal lakes of Lago Salso (north) and Lago Salpi (south). Pollen data show the expansion of halophytic herbs under local brackish conditions during the Early Meghalayan and the continuous spread of dryland herbs consistent with the closure of the basin. The alluvial plain progradation during the Late Meghalayan allowed the intensive exploitation of the area and the development of a highly anthropogenic landscape. The development of the settlements of pre-Roman Salpia Vetus, Roman Salapia, and Medieval Salpi was mainly determined by the insalubrious condition of the surrounding marshes, due to the reduction in water depth and oscillations in salinity.

Mediterranean climates are characterized by strong seasonal contrasts between dry summers and wet winters. Changes in winter rainfall are critical for regional socioeconomic development, but are difficult to simulate accurately1 and reconstruct on Quaternary timescales. This is partly because regional hydroclimate records that cover multiple glacial-interglacial cycles2,3 with different orbital geometries, global ice volume and atmospheric greenhouse gas concentrations are scarce. Moreover, the underlying mechanisms of change and their persistence remain unexplored. Here we show that, over the past 1.36 million years, wet winters in the northcentral Mediterranean tend to occur with high contrasts in local, seasonal insolation and a vigorous African summer monsoon. Our proxy time series from Lake Ohrid on the Balkan Peninsula, together with a 784,000-year transient climate model hindcast, suggest that increased sea surface temperatures amplify local cyclone development and refuel North Atlantic low-pressure systems that enter the Mediterranean during phases of low continental ice volume and high concentrations of atmospheric greenhouse gases. A comparison with modern reanalysis data shows that current drivers of the amount of rainfall in the Mediterranean share some similarities to those that drive the reconstructed increases in precipitation. Our data cover multiple insolation maxima and are therefore an important benchmark for testing climate model performance.

The Mediterranean region and the Levant have returned some of the clearest evidence of a climatically dry period occurring around 4200 years ago. However, some regional evidence is controversial and contradictory, and issues remain regarding timing, progression, and regional articulation of this event. In this paper, we review the evidence from selected proxies (sea-surface temperature, precipitation, and temperature reconstructed from pollen, 18O on speleothems, and 18O on lacustrine carbonate) over the Mediterranean Basin to infer possible regional climate patterns during the interval between 4.3 and 3.8 ka. The values and limitations of these proxies are discussed, and their potential for furnishing information on seasonality is also explored. Despite the chronological uncertainties, which are the main limitations for disentangling details of the climatic conditions, the data suggest that winter over the Mediterranean involved drier conditions, in addition to already dry summers. However, some exceptions to this prevail – where wetter conditions seem to have persisted – suggesting regional heterogeneity in climate patterns. Temperature data, even if sparse, also suggest a cooling anomaly, even if this is not uniform. The most common paradigm to interpret the precipitation regime in the Mediterranean – a North Atlantic Oscillation-like pattern – is not completely satisfactory to interpret the selected data.

This study reviews and synthesises existing information generated within the SCOPSCO (Scientific Collaboration on Past Speciation Conditions in Lake Ohrid) deep drilling project. The four main aims of the project are to infer (i) the age and origin of Lake Ohrid (Former Yugoslav Republic of Macedonia/Republic of Albania), (ii) its regional seismotectonic history, (iii) volcanic activity and climate change in the central northern Mediterranean region, and (iv) the influence of major geological events on the evolution of its endemic species. The Ohrid basin formed by transtension during the Miocene, opened during the Pliocene and Pleistocene, and the lake established de novo in the still relatively narrow valley between 1.9 and 1.3 Ma. The lake history is recorded in a 584m long sediment sequence, which was recovered within the framework of the International Continental Scientific Drilling Program (ICDP) from the central part (DEEP site) of the lake in spring 2013. To date, 54 tephra and cryptotephra horizons have been found in the upper 460m of this sequence. Tephrochronology and tuning biogeochemical proxy data to orbital parameters revealed that the upper 247.8m represent the last 637 kyr. The multi-proxy data set covering these 637 kyr indicates longterm variability. Some proxies show a change from generally cooler and wetter to drier and warmer glacial and interglacial periods around 300 ka. Short-term environmental change caused, for example, by tephra deposition or the climatic impact of millennial-scale Dansgaard–Oeschger and Heinrich events are superimposed on the long-term trends. Evolutionary studies on the extant fauna indicate that Lake Ohrid was not a refugial area for regional freshwater animals. This differs from the surrounding catchment, where the mountainous setting with relatively high water availability provided a refuge for temperate and montane trees during the relatively cold and dry glacial periods. Although Lake Ohrid experienced significant environmental change over the last 637 kyr, preliminary molecular data from extant microgastropod species do not indicate significant changes in diversification rate during this period. The reasons for this constant rate remain largely unknown, but a possible lack of environmentally induced extinction events in Lake Ohrid and/or the high resilience of the ecosystems may have played a role.

In this paper earthquake damage scenarios for residential buildings (about 4200 units) in Potenza (Southern Italy) have been estimated adopting a novel probabilistic approach that involves complex source models, site effects, building vulnerability assessment and damage estimation through Damage Probability Matrices. Several causative faults of single seismic events, with magnitude up to 7, are known to be close to the town. A seismic hazard approach based on finite faults ground motion simulation techniques has been used to identify the sources producing the maximum expected ground motion at Potenza and to generate a set of ground motion time histories to be adopted for building damage scenarios. Additionally, site effects, evaluated in a previouswork through amplification factors of Housner intensity, have been combined with the bedrock values provided by hazard assessment. Furthermore, a new relationship between Housner and EMS-98 macroseismic intensity has been developed. This relationship has been used to convert the probability mass functions of Housner intensity obtained from synthetic seismograms amplified by the site effects coefficients into probability mass function of EMS-98 intensity. Finally, the Damage Probability Matrices have been applied to estimate the damage levels of the residential buildings located in the urban area of Potenza. The proposed methodology returns the full probabilistic distribution of expected damage, thus avoiding average damage index or uncertainties expressed in term of dispersion indexes.

Il contributo riporta i risultati di analisi numeriche finalizzate a simulare gli effetti di sito e la non uniforme e anomala distribuzione dei danni agli edifici della cittadina di San Giuliano di Puglia (CB, Italia), durante la sequenza sismica del Molise (2002). Infatti, gli edifici nella parte più antica della città, di origine medievale, hanno riportato meno danni rispetto alla più moderna zona di espansione, mentre il comune nella sua interezza ha subito un livello di danneggiamento decisamente superiore a quello riscontrato nei comuni limitrofi. Il lavoro si basa innanzitutto su una indagine “a tappeto”, sia tipologica che relativa al danneggiamento riportato dagli edifici, realizzata mediante rilievo diretto sul campo da un gruppo di tecnici esperti nel novembre del 2002. Il database che ne è scaturito è stato in seguito accuratamente verificato, corretto (quando necessario) ed elaborato. Dopo il terremoto, sono state inoltre realizzate anche estese ed accurate campagne di indagine geotecnica, finalizzate sia alla microzonazione sismica sia, due anni più tardi, alla ricostruzione della città. Tali dati hanno permesso una definizione dettagliata del modello di sottosuolo. La profondità e la geometria del substrato roccioso sono state valutate sulla base di prove geofisiche profonde e grazie all'interpretazione degli aftershock registrati. Al fine di riprodurre l’azione sismica sugli edifici, sono stati considerati in questo studio i risultati di simulazioni di risposta locale con modelli 2D e 3D (descritti in un lavoro riportato su questo stesso volume). Nel presente lavoro, pertanto, si illustrano le caratteristiche tipologiche degli edifici e, sulla base della distribuzione della vulnerabilità conseguentemente stimata, si predispongono degli scenari di danno fisico utilizzando in input l’azione sismica ottenuta dai due modelli di risposta sismica locale. I risultati delle simulazioni sono quindi confrontati con la distribuzione di danno rilevato nell’immediato post–sisma.