Minoan Eruption Research Articles

Discovery of a tsunami deposit from the Bronze Age Santorini eruption at Malia (Crete): impact, chronology, extension

A geomorphological survey immediately west of the Minoan town of Malia (Crete) shows that a tsunami resulting from the Bronze Age Santorini eruption reached the outskirts of the Palatial center. Sediment cores testify a unique erosional event during the Late Minoan period, followed locally by a high energy sand unit comprising marine fauna. This confirms that a tsunami impacted northern Crete and caused an inundation up to 400 m inland at Malia. We obtained a radiocarbon range of 1744–1544 BCE for the secure pre-tsunami context and an interval 1509–1430 BCE for the post-event layer. Examination of tsunami deposits was used to constrain run-up not exceeding 8 m asl. The results open the field for new research on the Bronze Age Santorini tsunami regarding both impact and consequences for the Minoan civilization.

A modelling approach to the investigation of the effects of the Minoan supervolcanic eruption on Aegean sand fly diversity

The late Bronze Age eruption of the Thera volcano was among the largest eruptions of the Holocene era. This catastrophic event might perish all organisms from the ancient Santorini and could seriously impact the sand fly fauna of the Aegean islands. To investigate these effects, the survival possibility of the sand fly fauna in the Santorini islands and the biogeographic investigation of the sand fly fauna of eleven Aegean islands were conducted. It was found that only the south and east slopes of the massifs of Thira could provide refuge for sand fly populations. The expression-based heat map of the Jaccard coefficient matrix data showed that the Santorini islands and their neighbouring Anafi, Folegandros had clearly different z-score patterns compared to the other islands. It could be a late sign of the devastating effect of the Minoan eruption and/or the consequence of the distance of these islands from the mainland. Neither the glacial seashore patterns nor the geographic-climatic conditions can explain the present sand fly fauna of the Aegean Archipelago. If the sand fly populations of ancient Santorini survived the Minoan cataclysm, it could indicate that the environmental tolerance and the resilience of the sand fly populations can be high, and local geological and geomorphological conditions can play a greater role in the survival of sand fly species than previously assumed.

Volcanotectonic interactions between inclined sheets, dykes, and faults at the Santorini Volcano, Greece

Dykes and inclined sheets are known occasionally to exploit faults as parts of their paths, but the conditions that allow this to happen are still not fully understood. In this paper, we report field observations from a swarm composed of 91 segments of dykes and inclined sheets, the swarm being particularly well-exposed in the mechanically layered caldera walls of the Santorini volcano, Greece. Here the focus is on dykes and sheets in the swarm that are seen deflected into faults and the mechanical conditions that encourage such deflections. In particular, we present new analytical and numerical models to explain the mechanical principles of dyke/sheet deflections into faults. The numerical models are applied to a normal-fault dipping 65° with a damage zone composed of parallel layers or zones of progressively stiffer rocks with increasing distance from the fault rupture plane. We model a sheet-intrusion, dipping from 0° to 90° and with an overpressure of alternatively 1 MPa and 5 MPa, approaching the fault. We further tested the effects of changing (1) the thickness of the sheet-intrusion, (2) the fault-zone thickness, (3) the fault-zone dip-dimension (height), and (4) the loading by, alternatively, regional tension and compression. We find that the stiffness of the fault core, where a compliant core characterises recently active fault zones, has pronounced effects on the orientation and magnitudes of the local stresses and, thereby, on the likelihood of dyke/sheet deflection into the fault zone. Similarly, the analytical models, focusing on the fault-zone tensile strength and energy conditions for dyke/sheet deflection, indicate that dykes/sheets are most likely to be deflected into and use steeply dipping recently active (zero tensile-strength) normal faults as parts of their paths.

Volcanic ash and tsunami record of the Minoan Late Bronze Age Eruption (Santorini) in a distal setting, southwestern Turkey

ABSTRACTWe present the volcanic ash and tsunami record of the Minoan Late Bronze Age Eruption of Santorini (LBAES) in a distal setting in southwestern Turkey. In one of the drilled cores at the Letoon Hellenic antique site on Eşençay Delta, we encountered a 4 cm thick tephra deposit underlain by 46 cm thick tsunami‐deposited sand (tsunamite), and an organic‐rich layer that we 14C dated to 3295 ± 30 bp or 1633 bc. The relationship between Santorini distal volcanic ash and underlying tsunamite is described and interpreted. LBAES occurred in four main phases: (1) plinian; (2) phreatomagmatic; (3) phreatomagmatic with mudflows; and (4) ignimbritic flows and co‐ignimbrite tephra falls. In this study, we aim to understand which eruptive phases generate distal ash during the Minoan eruptive sequence by examining the 3D surface morphology of ash formed by different fragmentation processes. To that end, we used numerous statistical multivariates, 3D fractal dimension of roughness, and a new textural parameter of surface area‐3D/plotted area‐2D to characterise the eruption dynamics. Based on ash surface morphologies and the calculated statistical parameters, we propose that that distal ash is represented by a single layer composed of well‐mixed (coarse to fine) magmatic and phreatomagmatic ash.

Greece and Turkey Shaken by African tectonic retreat

Earthquakes are a consequence of the motions of the planet’s tectonic plates, yet predicting when and where they may occur, and how to prepare remain some of the shortcomings of using scientific knowledge to protect human life. A devastating Mw 7.0 earthquake on October 30, 2020, offshore Samos Island, Greece was a consequence of the Aegean and Anatolian upper crust being pulled apart by north–south extensional stresses resulting from slab rollback, where the African plate is subducting northwards beneath Eurasia, while the slab is sinking by gravitational forces, causing it to retreat southwards. Since the retreating African slab is coupled with the overriding plate, it tears the upper plate apart as it retreats, breaking it into numerous small plates with frequent earthquakes along their boundaries. Historical earthquake swarms and deformation of the upper plate in the Aegean have been associated with massive volcanism and cataclysmic devastation, such as the Mw 7.7 Amorgos earthquake in July 1956 between the islands of Naxos and Santorini (Thera). Even more notable was the eruption of Santorini 3650 years ago, which contributed to the fall of the Minoan civilization. The Samos earthquake highlights the long historical lack of appreciation of links between deep tectonic processes and upper crustal deformation and geological hazards, and is a harbinger of future earthquakes and volcanic eruptions, establishing a basis for studies to institute better protection of infrastructure and upper plate cultures in the region.

Evolution of magma decompression and discharge during a Plinian event (Late Bronze-Age eruption, Santorini) from multiple eruption-intensity proxies

We have coupled three independent methods to investigate the time evolution of eruptive intensity during the sub-Plinian and Plinian phases of the 3600-year BP Late Bronze-Age eruption of Santorini Volcano: (1) mass eruption rate based on new lithic isopleth maps for multiple layers of the fall deposit, (2) magma decompression rate calculated from vesicle number densities, and (3) magma decompression rate calculated from H2O gradients in melt reentrants, with methods 2 and 3 measured on the same suite of pyroclasts. Mass eruption rate increased by two orders of magnitude, reaching 210 × 106 kg s−1 at the peak of the Plinian phase (plume height 28.4 ± 1.0 km); it then declined in the final stage of fallout emplacement following the first generation of pyroclastic surges. Decompression rates from melt reentrants (0.008 to 0.25 MPa s−1) are two to three orders of magnitude lower than those from vesicle number densities, assuming heterogeneous vesicle nucleation (2 to 19 MPa s−1). Melt reentrants are thought to record slow decompression in the deep feeder conduit, whereas vesicles record much higher rates of decompression in the shallow conduit due to the steep, nonlinear pressure gradients associated with magma vesiculation and fragmentation. Upwardly converging flow from a dike-like, deep conduit to a more cylindrical, shallow conduit may also have played a role in causing upwardly accelerating flow. Variations in deep decompression rate recorded by melt reentrants are decoupled from mass eruption rate, whereas those recorded by vesicles lie in between. Taken with the transition from unsteady to steady Plinian eruption, this may reflect the existence of transient flow conditions in the conduit system due to widening and lengthening of a deep feeder dike as Plinian eruption progressed. As the mass eruption rate rose to its peak value, the fragmentation level fell in the conduit due to increasing rates of magma strain and decompression.

Land-sea correlations in the Eastern Mediterranean region over the past c. 800 kyr based on macro- and cryptotephras from ODP Site 964 (Ionian Basin)

Direct correlations between terrestrial and marine climate-proxy records are essential in order to determine potential lead/lag relationships in the response of the terrestrial and marine realms to climate forcing. In the Eastern Mediterranean region, such land-sea correlations have not yet been established beyond c. 200 ka. To explore the potential of tephra layers for Late and Middle Pleistocene land-sea correlations in the Eastern Mediterranean region, we have revisited yet unconfirmed tephra layers previously reported from Ocean Drilling Program (ODP) Site 964 (Ionian Basin) for the past c. 800 kyr in order to identify their origin and examine potential terrestrial counterparts. Using major- and trace-element glass analyses, we confirmed the presence of seven visible tephra layers with ages from 623 to 38 ka. These tephra layers represent known tephra isochrons from Italian volcanic centers (Y-5, Y-7, X-6, and V-0) and three yet unknown eruptions from Etna (623 ka), the Campanian Volcanic Zone (CVZ; 238 ka), and Pantelleria (238 ka). Because the majority of the previously reported tephra layers from ODP Site 964 were identified as clastic layers of non-volcanic origin, cryptotephra analyses were carried out for cores spanning Marine Isotope Stages (MIS) 13 to 9 (500–320 ka). This effort yielded 19 cryptotephra layers originating from Santorini volcano, the CVZ, possibly Roccamonfina volcano, and an undefined source in either the Aeolian Islands or the South Aegean Volcanic Arc. Two tephra layers are correlated with potential equivalents from terrestrial archives on the Italian and Balkan Peninsulas, including tephra isochrons SC5/A7/OH-DP-1966 (c. 493 ka; Mercure basin, Acerno basin, and Lake Ohrid) and TP09–65.95 (c. 359 ka; Tenaghi Philippon) that represent an unknown eruption of Roccamonfina and the Cape Therma 1 eruption of Santorini, respectively. Direct linking of the marine record from ODP Site 964 with the terrestrial records from Tenaghi Philippon, Lake Ohrid, and the Acerno basin via tephra tie points allowed us to circumvent shortcomings of the individual age models, and to obtain a comprehensive picture of climate variability in the greater Eastern Mediterranean region for the MIS 13–9 interval.

Discovery of annual growth in a modern olive branch based on carbon isotopes and implications for the Bronze Age volcanic eruption of Santorini

The volcanic eruption of Santorini in the Bronze Age left detectable debris across the Mediterranean, serving as an anchor in time for the region, synchronizing chronologies of different sites. However, dating the eruption has been elusive for decades, as radiocarbon indicates a date about a century earlier than archaeological chronologies. The identification of annual rings by CT in a charred olive branch, buried alive beneath the tephra on Santorini, was key in radiocarbon dating the eruption. Here, we detect a verified annual growth in a modern olive branch for the first time, using stable isotope analysis and high-resolution radiocarbon dating, identifying down to the growing season in some years. The verified growth is largely visible by CT, both in the branch’s fresh and charred forms. Although these results support the validity of the Santorini branch date, we observed some chronological anomalies in modern olive and simulated possible date range scenarios of the volcanic eruption of Santorini, given these observed phenomena. The results offer a way to reconcile this long-standing debate towards a mid-sixteenth century BCE date.

Synchronous Pumice Mantle Found on Santorini Volcano

It is generally accepted that the vent of the 3.6 ka Minoan eruption was situated in the water-filled Santorini caldera prior to the Minoan eruption. One should therefore expect to find huge quantities of pumice and ash on the inner side of the caldera walls, but there is only a relatively small amount preserved. An unexpected discovery of remnants of a synchronous pumice mantle of the Minoan eruption appears to solve this enigma. A lengthy period of erosion and the intensive quarrying of pumice for the construction of the Suez Canal (1859 to 1869) led to the removal of an enormous amount of material and information for generations of geologists. The synchronous pumice mantle covered the whole caldera wall from rim to sea level. Archaeological finds under the pumice mantle show that the caldera wall was accessible and inhabited in the Bronze Age. Furthermore, this discovery documents that only one Minoan eruption took place and that the so-called “Lower pumice” does not exist on Santorini.

Evolution of a social dynamic in a changing landscape: the case of Argos (Argolis, Greece) in the Mycenaean period

Argos in the Mycenaean period consists of a real enigma. Compared to its neighbours, amongst others Mycenae, Tiryns and Midea, Argos, after being a flourishing center in the Middle Helladic period, lost of it’s importance until the End of the Mycenaean palatial period, while maintaining a continuous occupation. During the transitional phase (MH III/LH I), and despite the fact that some parts of the argiv settlement continues to grow, as shown in particular by the work undertaken on the fortified acropolis of the Aspis, Argos, will experience a gradual decline as shown in particular through the abandonment of certain residential areas and the relocation of some population groups within and probably beyond its borders. According to one possible scenario, a group of people moved, at the very beginning of MH III, from Argos to Mycenae participating in the spectacular rise of Mycenae from the late MH period and onwards.Through this communication, we will first try to demonstrate, based on the archaeological reality, the status of Argos from the transitional phase (MH III/LH I) and during the LH period within the organization of the Argolis. In a second step, we will try to define the causes that influenced the evolution of this status. We will demonstrate how a series of natural disasters and in particular the eruption of Thera may have influenced the political, economic and social geography of the Argolis to the detriment of Argos. Based on the archaeological discoveries and the Adaptive Cycle (AC) model, we will show how some sites or parts of the Argolis functioned according to a positive/negative system throughout the protohistoric periods.

Climate disaster and the resilience of local maritime networks: Two examples from the Aegean Bronze Age

This paper investigates changing patterns of maritime small-world networks among the Cycladic islands of the southern Aegean Sea in the context of two climate disasters in the Bronze Age (ca. 3200 BCE - 1100 BCE): the 4.2 ka event at the end of the Early Bronze Age and the eruption of Thera in the late 17th century BCE in the Late Bronze Age. The 4.2 ka event is a period where changing environmental conditions — including landscape degradation, deforestation, and increased drought — correlate with drastically reduced maritime connectivity and increased settlement isolation. Previous archaeological study of the eruption of the Theran volcano (Santorini) has shown the persistence of regional-scale communication networks for a period of up to a century after the eruption. This paper examines the effect of the eruption on local-scale maritime networks. The archaeological study of both climate events is complicated by chronological discrepancies and, in the case of the 4.2 ka event, reliance on indirect environmental data.This paper addresses the questions: a) what effect did these two climate disasters have on small-world maritime networks in the Bronze Age Cyclades, and b) how did the island inhabitants adapt within a context of disruptive environmental phenomena? GIS modeling reveals that small-world networks in the Early Bronze Age Cyclades were substantially altered in the face of the 4.2 ka climate event, while in response to the eruption of Thera, small-world networks were resilient. Variables influencing the differing network responses include the temporality of the climate disasters, the availability of the sail as a technology of resilience, and varying environmental and social vulnerabilities.

A New Annual14C Dataset for Calibrating the Thera Eruption

ABSTRACTAnnually resolved tree-ring samples of the time period 1625–1510 BCE were analyzed from the German oak tree-ring chronology. Blocks of the same tree rings were previously used to generate IntCal calibration data. The new dataset shows an offset to the calibration data IntCal13 of 24 years and resembles annual data for the same time period derived from tree-ring records in other growth locations. A subset of samples of the period 1625–1585 BCE was additionally measured in three other laboratories (ETH, AAR, AA) for quality control.

First Speleothem Evidence of the Hiera Eruption (197 BC), Santorini, Greece

ABSTRACT Speleothems are useful in detecting past geoenvironmental events. Variations in trace element concentrations may constitute a diagnostic of volcanic eruptions, enabling both dating and environmental impact assessment. This work attempts to detect possible ‘signatures’ of past volcanic eruptions in speleothems from Zoodochos Pigi cave on Santorini. Higher-than-usual concentrations of elements and minerals (e.g. barium and monazite respectively) exotic to typical speleothem chemistry in a band within a flowstone retrieved from the cave were revealed through SEM-EDS and XRD analyses and thought to be of volcanic origin. By chance, charcoal trapped in the said speleothem band allowed dating to establish the timing of the volcanic event. The radiocarbon date pointed towards the historically documented Hiera eruption, the earliest of a series of volcanic eruptions that postdate the Minoan eruption. The Hiera eruption, although less violent than the Minoan eruption, signallised the recrudescence of intracaldera activity which culminated in the formation of Palea Kameni (197 BC) with palpable effects on the regional environment. The interpretation of the results presented here, i.e. geochemical analysis on speleothems and radiocarbon dating, are cross-correlated with the well-documented timeline of eruptions of Santorini and ancient literature.

Wood from the Netherlands around the Time of the Santorini Eruption Dated by Dendrochronology and Radiocarbon

ABSTRACTEighteen new high-precision radiocarbon (14C) dates obtained for dendrochronologically dated wood from Bodegraven, the Netherlands are reported. They are relevant for establishing the revised calibration curve around the time of the Bronze Age Santorini eruption. Most of our new data overlap within one sigma with IntCal13, but a few data points are slightly increased in 14C age compared to IntCal13.

Recent Developments in Calibration for Archaeological and Environmental Samples

ABSTRACTThe curves recommended for calibrating radiocarbon (14C) dates into absolute dates have been updated. For calibrating atmospheric samples from the Northern Hemisphere, the new curve is called IntCal20. This is accompanied by associated curves SHCal20 for the Southern Hemisphere, and Marine20 for marine samples. In this “companion article” we discuss advances and developments that have led to improvements in the updated curves and highlight some issues of relevance for the general readership. In particular the dendrochronological based part of the curve has seen a significant increase in data, with single-year resolution for certain time ranges, extending back to 13,910 calBP. Beyond the tree rings, the new curve is based upon an updated combination of marine corals, speleothems, macrofossils, and varved sediments and now reaches back to 55,000 calBP. Alongside these data advances, we have developed a new, bespoke statistical curve construction methodology to allow better incorporation of the diverse constituent records and produce a more robust curve with uncertainties. Combined, these data and methodological advances offer the potential for significant new insight into our past. We discuss some implications for the user, such as the dating of the Santorini eruption and also some consequences of the new curve for Paleolithic archaeology.

Annual Variation in Atmospheric 14C Between 1700 BC and 1480 BC

ABSTRACTIn 2018 Pearson et al. published a new sequence of annual radiocarbon (14C) data derived from oak (Quercus sp.) trees from Northern Ireland and bristlecone pine (Pinus longaeva) from North America across the period 1700–1500 BC. The study indicated that the more highly resolved shape of an annually based calibration dataset could improve the accuracy of 14C calibration during this period. This finding had implications for the controversial dating of the eruption of Thera in the Eastern Mediterranean. To test for interlaboratory variation and improve the robustness of the annual dataset for calibration purposes, we have generated a replicate sequence from the same Irish oaks at ETH Zürich. These data are compatible with the Irish oak 14C dataset previously produced at the University of Arizona and are used (along with additional data) to examine inter-tree and interlaboratory variation in multiyear annual 14C time-series. The results raise questions about regional 14C offsets at different scales and demonstrate the potential of annually resolved 14C for refining subdecadal and larger scale features for calibration, solar reconstruction, and multiproxy synchronization.

Precursory eruptive activity and implied cultural responses to the Late Bronze Age (LBA) eruption of Thera (Santorini, Greece)

The Late Bronze Age (LBA) eruption (ca. 1650 BCE) of Thera (Santorini) was one of the largest known in history, burying and destroying a thriving Theran (Cycladian) culture that occupied the island and surrounding islands. The consequent thick tephra deposit provides detailed information on the eruptive sequence and vent mechanics – it also provides details on that culture through burial of towns, farmsteads, and landscapes, the most prominent being the town of Akrotiri on the south coast of Thera. Here stratigraphic relationships between volcanic and archaeological deposits/constructions clearly indicate this eruption was signaled by seismic and minor eruptive events precursory to the main Plinian eruption. Because no casualties have yet been found beneath the tephra, inhabitants had advance notice of the impending disaster by a precursory eruption whose deposits are well preserved both within the archaeological site and in geological exposures throughout southern Thera island – and escaped by boat. Yet archaeological sites on nearby islands rarely record an influx of new arrivals at this time. Accordingly, it is suggested here that those escaping were incinerated at sea by pyroclastic density currents that swept across the ocean surface during the second phase of the Plinian eruption.

Securing timelines in the ancient Mediterranean using multiproxy annual tree-ring data

Calendar-dated tree-ring sequences offer an unparalleled resource for high-resolution paleoenvironmental reconstruction. Where such records exist for a few limited geographic regions over the last 8,000 to 12,000 years, they have proved invaluable for creating precise and accurate timelines for past human and environmental interactions. To expand such records across new geographic territory or extend data for certain regions further backward in time, new applications must be developed to secure "floating" (not yet absolutely dated) tree-ring sequences, which cannot be assigned single-calendar year dates by standard dendrochronological techniques. This study develops two approaches to this problem for a critical floating tree-ring chronology from the East Mediterranean Bronze-Iron Age. The chronology is more closely fixed in time using annually resolved patterns of 14C, modulated by cosmic radiation, between 1700 and 1480 BC. This placement is then tested using an anticorrelation between calendar-dated tree-ring growth responses to climatically effective volcanism in North American bristlecone pine and the Mediterranean trees. Examination of the newly dated Mediterranean tree-ring sequence between 1630 and 1500 BC using X-ray fluorescence revealed an unusual calcium anomaly around 1560 BC. While requiring further replication and analysis, this anomaly merits exploration as a potential marker for the eruption of Thera.

Dyke-arrest scenarios in extensional regimes: Insights from field observations and numerical models, Santorini, Greece

During a volcanic unrest period with magma-chamber rupture, fluid-driven fractures (dykes) are injected either from deep reservoirs or shallow magma chambers. Subsequently, the dykes follow propagation paths towards the surface, some eventually reaching the surface to erupt while others become arrested. Here we study dyke paths resulting in eruption or arrest in an excellent 5-km wide exposure of the northern caldera wall of the Santorini volcano in Greece. Mapping of >90 dyke segments shows that they were emplaced in a host rock consisting of layers (of breccia, tuff, scoria, and lava) with a wide variety of mechanical properties. At the contacts, some dykes are arrested or deflected and hence change their propagation paths. Here we combine the field data with numerical models to explore dyke paths resulting in (1) arrest and (2) eruption. We investigate the effect of different host-rock mechanical properties, magmatic overpressures, and tectonic loading on dyke paths. We find that layers with unfavorable local stresses for dyke propagation, namely stress barriers, result from layer stiffness (Young's modulus) contrast and thickness variations and are a common cause of dyke arrest. The study also shows how the details of the dyke path, and eventually dyke-fed eruptions, depend on the mechanical layering and local stresses in volcanoes. The results are of great importance for understanding dyke-propagation paths, and the likelihood of eruption, during unrest periods, particularly in stratovolcanoes fed by shallow chambers, such as Santorini.

Islands of Time. Unsettling Linearity Across Deep History

ABSTRACT Based on archaeological and anthropological data on the socio-political effects of two historically distant extreme occurrences in nature, we explore how certain types of events unsettle progressive chronology to the extent of establishing periodic intervals of circular and repetitive temporality; ‘islands of time’. The article is built around a comparison of the socio-temporal repercussions of two extreme natural events: the El Niño-related flooding that hit southern Mozambique early in 2000 CE and the Thera eruption on Crete around 1600 BCE. Using the former as a ‘trans-temporal hinge’ for connecting otherwise disparate temporal occurrences, we show how event episodes like the Mozambique floods and the Thera eruption twist free from the hold of linearity by continuously ‘looping’ time around themselves and thereby (re)actualising their own conditions of existence. In our analysis, the empirical point of contact between the two cases is architecture and how negotiations of the built environment reflect temporal looping.