Present-day stress field pattern in the Vrancea seismic zone (Romania) deduced from earthquake focal mechanism inversion

Vrancea seismogenic zone in the South-Eastern Carpathians is characterized by localized intermediate-depth seismicity. Due to its complex geodynamics and large strain release, Vrancea represents a key element in the Carpatho-Pannonian system. Data from a recently compiled catalogue of fault plane solutions (REFMC) are inverted to evaluate stress regime in Vrancea on depth. A single predominant downdip extensive regime is obtained in all considered clusters, including the crustal layers located above the Vrancea slab. The prevalent stress regime confirms previous investigations and requires some mantle-crust coupling. The S3 principal stress is close to vertical, while S1 and S2 are horizontal, oriented perpendicularly and respectively tangentially to the Carpathians Arc bend. This configuration is present at any depth level. According to seismicity patterns, there are two main active segments in the Vrancea intermediate-depth domain, at 55 – 105 km and 105 – 180 km, both able to generate major events. The configuration of the tectonic stresses as resulted from inversion is similar in both segments. Also, high fault instability (I > 0.95) is characterizing the segments. The only notable difference is given by the friction and stress ratio parameters which drop down in the bottom segment from μ = 0.95 to μ = 0.55 and from R = 0.51 to R = 0.29. This variation is attributed to possible weakening processes activated below 100 km depth and can explain the intensification of seismicity production as earthquake rate and average energy release in the lower segment versus the upper segment.

Paleomagnetic Results from Western Anatolia: Evidence of Microblock Rotations after Emplacement of the Lower Miocene Yuntdağ Volcanic Rocks

The eastern Aegean region has undergone north dipping subduction in the Oligocene, continental collision and then Miocene-Pliocene extension, which is associated with widespread Miocene volcanism. The aim of this study is to assess the possibility of block rotations due to stress variations in the Dikili (İzmir) province, Western Anatolia, based on paleomagnetic data obtained from 35 independent sites in addition to results from 19 sites in earlier studies. The lower Miocene Yuntdağ volcanic rocks were emplaced in three different structural blocks, the Dikili, Zeytindağ and Bergama blocks. Clockwise rotation is found in the Dikili and Zeytindağ blocks that varies from R (± DR) = 12.5° (± 7.4°) in the west to R (± DR) = 35.6°± (13.2°) in the east, respectively. In contrast, a counterclockwise rotation of R (± DR) =-38.1° (± 6.4°) resulted in the Bergama block, in the north of the Dikili and Zeytindağ blocks. A scissor-like basin evolution is suggested during the opening of the Bakırçay graben which led to counterclockwise rotation of the Bergama block and clockwise rotation of the Dikili and Zeytindağ blocks after lower Miocene to present. The rotation pattern derived from results of this study demonstrates that localized small scale deformation due to basin evolution besides regional affects must be considered as part of the deformation matrix in this area.

The loss of geological memory of past catastrophes: the case of Pompeii

In 79 A.D. Vesuvius buried entire cities in a few days under a blanket of pumice and ashes. It was a sudden event, which occurred after centuries of inactivity, heralded only by earthquakes that repeated periodically, for many years, creating addiction rather than alarm. After the event, the vegetation covered the volcanic products, and the memory of the disaster was lost. The first excavations began in Herculaneum in 1738 and in Pompeii ten years later, in times when archeology still did not exist. Much was destroyed, given away, thrown away. Almost intact buildings emerged, with all their contents, with many inhabitants caught on the run. The arduous process of recovering the sites has had important and not always happy stages, accompanied by continuous progress in the excavation methods. Volcanology has drawn from those experiences as much as it could, setting itself the goal of reconstructing the story of an explosive eruption, the first in the world to be described, by Pliny the Younger, the one that most left its mark on buildings, vegetation, animals and humans. Without the eruption, Pompeii and Herculaneum would have disappeared. The details on how the romans lost their lives in the tragedy is an important component to be offered to Pompeii’s visitors and that is at present largely imperfect. Knowing it and reconstructing its impact on people and the territory, going beyond the archaeological site, is an experience of the past and a warning for today and for the future.

Origins of Vulcanello based on the re-examination of historical sources (Vulcano, Aeolian Islands)

The lava platform and the three pyroclastic cones of Vulcanello constitute the northernmost volcanic structure of the island of Vulcano (Aeolian Islands). The sandy isthmus connecting the platform to the main island was definitively formed in the first half of the 1500s; before then, Vulcano and Vulcanello were two close but separate islands. For a long time, the interpretation of the sources of the II-I century BC, had considered the islet as built up about 2200 years ago. This belief, which proliferated among naturalists from the 17th century, is not confirmed in the ancient texts or even in the geographical documents of the time, which do not indicate the presence of Vulcanello as a new and stable island near Vulcano. The islet would only be mentioned at the dawn of the second millennium, and named in Arabic “Gabal’ al Burkān”, meaning Mount of Vulcano; shortly thereafter the toponym changed to the Latin “Insulam Vulcanelli” and then, towards the 15th century, finally to Vulcanello. Since the creation of a volcanic island certainly occurred in the Aeolian Islands in the classical era, but traces of it were quickly lost, the most plausible hypothesis is that it was formed in the area of the current Vulcanello, to be subsequently erased by the sea. The shallow, flat seabed, likely remaining as a result of sea abrasion, might have represented the morphological element on which the circular lava platform we know today was formed sometime between 950 and 1000 AD.

Resilience and adaptation to volcanoes in Late Middle Ages in Lipari island (Aeolian, Italy)

Volcanic activity resumed during early Middle Ages times at Lipari following at least 6000 years of quiescence. This phenomenon occurred in a social context that had continuously developed from prehistoric times to the Roman age and was burdened by a demographic crisis that involved the archipelago between the 6th and 11th century AD. The rare archaeological records relating to the 6th - 11th centuries suggest abrupt changes in the population of the islands. The medieval sources are rich in religious and fantastic references to volcanic events linked to Lipari and Vulcano, testifying the uneasy condition for the human communities. This work concerns the resilience and adaptation of the communities to volcanic activity during the Late Middle Ages in Lipari. Starting from 1083 the Aeolian archipelago was involved in a repopulation program, implemented in 1095 by the Constitutum and organized by the Benedictine Monastery with the annexed S. Bartolomeo Cathedral on the castle. From the 13th century the volcanic phenomena, strictly limited to the northern sector of the island, did not interfere as previously with the anthropic activities. The Monastery will be enlarged in the Norman phase during the first half of the 12th century with the construction of the cloister. New historical documents relating to the 1264, report news of fires and land movements on Lipari. Recent age determinations obtained for the obsidian flow of Rocche Rosse at 1220 ± 30 AD (archaeomagnetic dating) and for an obsidian block of the Lami pyroclastic cone at 1243 ± 190 (fission-track dating) allow to define the age of the last phase of activity of the Monte Pilato-Lami-Rocche Rosse complex, and to associate it the events reported on 1264’s historical documents. This work makes in comparison volcanological, archaeological and historical dates and described an updated summary of one of the lesser known phases of the history of the archipelago. The main consequence of the medieval volcanic activity at Lipari caused a clear division of the territory with the population confined in the southeast quadrant, protected to the north by Serra and Monte Rosa which represented a natural orographic barrier.

The paleo-lacustrine diatomaceous deposits of Monte Amiata volcano (Tuscany, Italy) and the Ezio Tongiorgi paleontological collection in the Museum of Natural History of the University of Pisa

At the foothillof Monte Amiata volcano (southern Tuscany, Italy), small extinct lake basins of late Pleistocene age are documented. These lake basins were characterized by the deposition of two very different types of sediment: a) derived from the authigenic precipitation of iron oxides (goethite) and exploited as earth pigments; b) biogenic siliceous sediment composed of fossil diatoms and named diatomaceous earth or diatomite. The lacustrine sediments of Mount Amiata volcano were widely exploited for various applications since ancient times. Literary documents begin in the 16th century, with the descriptions of Cesalpino, Gesner, Agricola, and Imperato. Specific references to the diatomites of Monte Amiata are quoted in the 17th century by Boccone and Bonanno. The quarrying activity was described by Micheli in 1733. During the 18th and 19th centuries, the diatomaceous earths of Monte Amiata are part of the important geological collections of Micheli, Targioni Tozzetti, Baldassarri, Campani, and Tommi. A particular significance has the collection of botanic and ichthyologic fossils collected by Ezio Tongiorgi, and now preserved in the Museum of Natural History of the University of Pisa sited at the Charterhouse of Pisa in the Calci village. These paleontological samples preserve the biological and physical testimonies of the environmental and climatic changes of the late Pleistocene and are now particularly valuable because they are the only remaining evidence of the diatomaceous lacustrine deposits of the paleo-lakes of Monte Amiata. For these reasons, they represent geological materials with a fundamental cultural value.

Should I stay or should I go? 6000 years of human presence and abandonments at Stromboli volcano and an overview on the whole Aeolian Archipelago (Southern Tyrrhenian Sea, Italy)

T The paper addresses the long-lasting human presence on the island of Stromboli, an active volcano at the northern edge of the Aeolian archipelago, in the Southern Tyrrhenian sea, Italy. A conceptual model has been built to explore the phenomenon, it takes into account a series of aspects comparing Stromboli to other islands: their morphology, natural resources and geography along with the archaeological and historical data and, further, human attitude to volcanic environments, to risk and to insularity has been deeply explored. We propose a complex narrative where a combination of geological, socio-economic, historical, and psychological factors influenced people’s choices and that human presence is related more to the volcanic (and island) environment (and opportunities) than to volcanic activity.

Disseminating the knowledge on the complex interactions between humans and volcanoes: the geological section of the Villa Arbusto archaeological museum at Lacco Ameno (Ischia, Naples - Italy)

A room in the Archaeological Museum of Villa Arbusto (Lacco Ameno, Ischia) was set up to house rocks and fossils collected by the renowned archaeologist Giorgio Buchner during his excavation activity on the Island of Ischia. The collection is witness to a long multidisciplinary research activity that saw archaeological studies at the center of volcanological, pedological and palaeoenvironmental researches, aimed at reconstructing the archaeological contexts in the complex geological dynamics of the island. In fact, during the different phases of colonization recorded on the island, the Ischia volcanoes were very active and produced explosive and effusive eruptions, accompanied by a strong geological dynamics that included earthquakes, landslides (even gigantic ones), rapid ground uplift and strong hydrothermal activity. In the room, the samples on display “tell” the evolution of the island and its dynamics in four windows and a chest of drawers, where there is an exposition of the products of the various eruptions, from the oldest to the most recent, sedimentary rocks and the collection of macro and microfossils found in marine sediments, displaced at variable altitudes by the rapid volcano-tectonic deformations that characterize the island. A series of panels and monitors accompany the visitor along a path that, starting from the geological evolution of the island, passes through the relationship between humans and the volcano, the main volcanic phenomena and the reconstruction of an archaeological excavation of exceptional value, where it is possible to see the strong interaction between primary and secondary volcanic phenomena and a human settlement of the first Greek colony in the west: Pithecusae. The exhibition was designed with the purpose of educating the visitors and the local population about the natural history of the island and its volcanoes, and their impact on the human life through time.

The millstone trade from the most exploited Italian volcanic areas: an overview from the phoenicians to the roman period

Lavas were widely used in antiquity to produce millstones. This is mainly due to their superior properties for grinding cereals and availability when compared with other rock-types. In the past four decades, several studies have been published about lava millstones discovered in subaerial and submarine archaeological sites of the Central-Western Mediterranean. Although the morphological evidence of old quarries is rarely present, all these studies were aimed at recognizing provenance and manufacturing areas of the volcanic raw material. Typologies of grinding tools coexisted in different periods, even if some technological developments marked transitions between cultures. The main chronology is: Archaic saddle quern, Greek hopper-rubber (Olynthian), small to medium size rotary device (Morgantina type) and large hourglass rotary millstone (Pompeian style). Potential volcanic sources are widespread throughout the entire Mediterranean region, but two main Italian quarrying areas of volcanic rocks for the manufacture of millstones from the Phoenician to the Roman period were pointed out. These are the Latium-Umbria border in Central Italy, and Sicily (Eastern Sicily and Sicilian Channel) in Southern Italy. In detail, analysis of the lava lithotypes shows that grinding tools were mainly constructed of: (i) a leucite phonolite of the so called “Orvieto quarries” between the localities of Sugano and Buonviaggio in the Roman Volcanic Province (High-K alkaline series); (ii) hawaiites and mugearites (Na-alkaline series) from Etna volcano; (iii) basalts (Tholeiitic/Transitional series) of the Hyblaean Mountains and (iv) basalts (Na-alkaline series) from Pantelleria Island (Sicilian Channel). Although some lava millstones from other volcanic regions are recorded, the above four Italian volcanic rock types represent the most exploited in antiquity. A comparison between volcanic millstones and outcropping lavas already exists, from literature data, through thin section modal mineralogy and conventional igneous petrology (i.e., TAS classification, magmatic affinities, and major-trace elements signature). Therefore, on this basis we propose a set of discriminating geochemical parameters (major-trace elements and element ratios diagrams) useful for a quick assessment tool to possibly evaluate one of these four exploited volcanic areas of Italy matching millstones. A sketch of volcanic millstone trade networks and commercial routes in antiquity throughout the Central-Western Mediterranean has been also reported and overviewed on the basis of the literature data.

Prehistoric human presence on Mount Etna (Sicily), in relation to the geological evolution

This study analyses the relationship between the pre- and protohistoric sites on the slopes of Etna and the volcanic products, as well as the diverse settlement strategies in the different periods of prehistory. New C14 dating from significant excavations, in addition to those known from other Etnean sites, were performed with the aim of validating the chronology of the sequence of the different phases. A substantial concordance of the archaeological data with the volcanological ones has been found. It has been observed that a consistent human presence on Etna appears from the Middle Neolithic (5500 BC), after the sequence of eruptive events that marked the end of the Ellittico volcano (13550 - 13050 BC) and the formation of the Valle del Bove, and the subsequent debris and alluvial events on the eastern flanks of the volcano (7250 - 3350 BC). Human presence intensifies between the Late-Final Copper Age and the Early Bronze Age (2800 - 1450 BC), due to improvement in subsistence techniques and to the large presence of soils on lava flows suitable for sheep farming. The most recent phases of the Bronze Age are poorly represented, probably because of the concentration of the population in larger agglomerations (Montevergine and S. Paolillo at Catania, the Historical Hill at Paternò). The explosive eruptions taking place in this period seem to have had less impact on the settlement choices and have not affected the development of the sites over time.