Volcanology

Ancient Volcanic Eruption

The devastating volcanic eruption of Thira has become the most famous single event in the Aegean before the fall of Troy. The eruption would have caused a significant climate upset for the eastern Mediterranean region. It was one of the biggest volcanic eruptions on Earth in the last few thousand years.

Dating the Volcanic Eruption

The exact date of the Minoan eruption provides a fixed point for aligning the entire chronology of the 2nd millennium in the Aegean, because evidence of the eruption occurs throughout the region.

Volcanism and Seismicity in Mediterranean Island Arcs

In island arc structures volcanism and seismicity are closely connected by tectonic, geological and geophysical features.

A Brief Note on Tectonic earthquakes Related to the Activity of Santorini from Antiquity to the Present

The author have compared all the available data for Santorini's past activity and the seismicity of its near environment and stated the fact that almost all of the known eruptions were preceded, accompanied and/or followed by shocks of tectonic origin.

Tectonic earthquakes and Santorini

Earthquakes that took place within a circle with a radius of some 420km around Santorini and within ~150 days from the start of a single eruption of short duration; also earthquakes preceding, accompanying and/or following longer periods of volcanic activity which lasted for months or a few years. r: Epicentral distance from the volcano (in km) t: Time-interval in days between the occurrence of the shock and the commencement of the outburst -If t is negative, then the sock preceded the start of the eruption -If t is positive, then the shock took place after the commencement of the outburst

Surveillance of Thera Volcano, Greece: Microseismicity Monitoring

A network of four portable seismic stations was established on the island of Thera, to monitor the micro-earthquake activity of the volcano. This network has been in operation for a few months every year since 1985.

Surveillance of Thera Volcano, Greece: Monitoring of the Geomagnetic Field

This paper presents the preliminary results of a volcano magnetic experiment under way in the area of Thera (Santorini) volcano, Greece, as part of a multi-disciplinary volcanic hazard assessment project.

Surveillance of Thera Volcano, Greece: Monitoring of the Local Gravity Field

This paper outlines the results of a microgravimetric network established in Thera as part of a multi-disciplinary program for the assessment of volcanic hazard in the area.

Long- and Short-term Predictions of Volcanic Eruptions in Santorini

The mean repeat time of the strong eruptions in the Santorini volcanic centre during the last five centuries is 94 years, with a standard deviation equal to 43 years.

Post-Minoan Volcanic Activity of the Santorini Volcano. Volcanic Hazard and Risk, Forecasting Possibilities

The study of the behaviour of the Santorini volcano during the period of post-Minoan volcanic activity allows us to suggest the most probable triggering mechanism of the volcanic eruptions as well as the mechanism of magma ascent, and to estimate the volcanic hazard and risk of a probable repetition of similar volcanic activity.

Traces of the Eruption Outside Thera

The eruption of Thera probably began and ended within the Cretan period of Late Minoan I A c. 1500 B.C. The horizon of fire-destruction in Crete in Late Minoan I B conventionally dated c. 1450 B.C. cannot be attributed to it, and must reflect the conquest of Crete by people from the Greek mainland a generation or more after the eruption.

The Eruption of the Volcano on Thera and the Destructions on Crete

There is no evidence to show that the Thera volcanic eruption caused any catastrophic disaster on Crete, and the author concludes that the Cretan destructions were more probably due to local earthquakes.

Age of Formation of the Aegean Active Volcanic Arc

In recent years many geological studies have been published on the Aegean plate, which constitutes part of the major Eurasiatic plate. Seismic data as well as Landsat photos have determined its boundaries.

Energetics of the Minoan Eruption: Some Revisions

Since the time of preparation of the first version of this paper (Wilson 1978 - subsequently referred to as Paper I) various new data have become available. Watkins et al. (1978) have presented measurements on the deep-sea ash layer from Santorini in the Eastern Mediterranean which extend the work of Ninkovich and Heezen (1965).

Geodynamic Considerations of the Development of the Hellenides

By considering all geophysical information available from the area of Greece, and particularly that of seismicity, deep seismic soundings, gravity and seismotectonics, a model of the geodynamic behavior of this region was developed (Makris 1977).

Mechanism of the Minoan Eruption of Santorini

The history of the Minoan eruption on the Santorini islands and subsequent caldera formation is described. It is found that only one tenth of the total tephra was ejected vertically. The remaining nine tenths emerged as lateral base surge and ash flow deposits. As result only small amounts of tephra were distributed over a large area by winds.

Prehistoric Pumice Tephra on Aegean Islands

Research related to the problem of the distribution of prehistoric Minoan tephra in the Aegean yielded new evidence on three points:

Fission Track Ages of Santorini Volcanics (Greece)

Fission track dating of zircon separated from the oldest tephra layers of Santorini indicate an age for the earliest eruptions of approximately one million years. Obsidian xenoliths from the Lower Pumice Series have a fission track age of approximately one hundred thousand years.

The Possible Effects of Santorini Tephra Fall on Minoan Crete

During the last decade controversy has continued as to the likely effects of the circa 1500 B.C. eruption of Santorini on the Minoan civilization centered on Crete some 100 km to the south of the volcano (Page 1970; Pichler & Schiering 1977).

Two Radiocarbon Dates of the Minoan Eruption on Santorini (Greece)

Two radiocarbon dates of the Minoan eruption on Santorini support an early date close to 1700 B.C. These "early" dates may possibly be influenced by emanations of old CO2-gas in volcanic surroundings.

Radiocarbon Dates from the Site of Akrotiri, Thera, 1967 - 1977: Addendum

The essentially inconclusive results from the 17 pertinent samples discussed earlier (Thera I, 791 - 795) have prompted me to extend the series from Akrotiri in order to obtain a more accurate picture.

Radiocarbon Dates from Akrotiri: Problems and a Strategy

In view of their scatter and the tendency of MASCA-corrected dates for Thera to be early, we now take a critical look at these dates and at other series dated by the radiocarbon laboratory at the University of Pennsylvania and by others.

Explosive Volcanism in the Hellenic Arc: a Summary and Review

The Hellenic arc is the site of extensive Quaternary explosive volcanism. Much progress has been made during recent years both in regional volcanostratigraphic knowledge and in the understanding of fundamental physical processes related to eruptive mechanisms of the major explosive eruptions.

The Pyroclastic Stratigraphy and Volcanology of Santorini

Santorini volcanic field has had 12 major (1-10 km3 or more of magma) and numerous minor explosive eruptions over the last 200 ka (Druitt et al. 1989).

Statistical Study on Santorini Pumice-falls

A population of 335 pumices from Santorini has been sampled and analysed by XRF.

Ash Layers of the Thera Volcanic Series: Stratigraphy, Petrology and Geochemistry

Stratigraphy and petrography have been carried out on measured sections from the Cape Therma-2 (C.T.-2) Pumice, the Bu-1 Pumice and the 'Minoan' (Bo) Pumice. Major and trace element analyses were made for 36 samples, and Sr and Nd analyses for a representative sample from each of the three pumice units.

Precursory Activity to the Minoan Eruption, Thera, Greece

Phreatic activity, consisting of steam blasts from accelerated hydrothermal activity, often precede major explosive eruptions.

The Minoan Deposits: a Review of their Characteristics and Interpretation

The Minoan deposits show evidence of four eruptive phases and a fluvial/erosion stage. The eruption began with a plinian phase which generated a column up to 36 km (± 5 km) high.

Assessment of Mass, Dynamics and Environmental Effects of the Minoan Eruption of Santorini Volcano

New data provide a basis for a reassessment of total erupted mass, eruption dynamics and environmental impact of the great Minoan eruption of Santorini volcano.

New Estimates for the Volume of the Minoan Eruption

The volumes of material erupted during the Bronze Age Minoan eruption have been recalculated, using an improved method and incorporating the new data published since the work of Watkins et al. (1978) and Bond and Sparks (1976).

Eruptive Mechanisms in the Minoan Eruption: Evidence from Pumice Vesicularity

The four primary phases of the Minoan eruption generated deposits whose characteristics reflect dominantly fall (phase 1) dominantly surge (phase 2) and flow (3 and 4) emplacement mechanisms and a wide variation in magma:water ratios.

A Palaeomagnetic Study of Minoan Age Tephra from Thera

This paper will describe work now in progress on tephra from the Minoan Age eruption of the Thera volcano. Downey and Tarling (1984) undertook an archaeomagnetic study of this tephra, and of material from fired destruction levels in Crete.

The Stronghyle Cladera: Geological, Palaeontological and Stable Isotope Evidence from Radiocarbon Dated Stromatolites from Santorini

Geochemical and palaeontological analyses have been carried out on radiometrically dated stromatolites, gastropods and marine travertines from Santorini (36.40° N, 25.40° B) in Greece. They occur as xenoliths in the pyroclastic flows of the third phase of the Minoan eruption.

Deterministic and Stochastic Models of the Seismic and Volcanic Events in the Santorini Volcano

The problem of forecasting future eruptions of Thera volcano has been approached by three models based on its past history. A deterministic model utilizes observations showing that in several circum-Pacific island arcs, as well as in the Hellenic arc, the onset time of eruption cycles depends on the occurrence time of seismic energy peaks associated with large mantle shocks.

How often does a Minoan Eruption Occur?

The average recurrence time of large explosive eruptions can be independently estimated by two methods: 1) graphical analysis of data on the frequency of historical eruptions plotted against their magnitude; and 2) tabulation of the age and volume of prehistoric caldera-forming eruptions.

The 1783 Eruption of Asama Volcano, Japan

Asama is a medium-sized, andesitic composite stratovolcano in central Japan. About 10 major eruptions occurred in the last 5000 years. The latest one took place in 1783, devastated about 500 km2 and killed 1200 people.

The Katmai Eruption of 1912: a Comparison with the Minoan Eruption of Santorini

The June 1912 eruption at Novarupta, adjacent to Mount Katmai on the Alaska Peninsula, is sometimes cited as a recent analog of the Minoan eruption of Santorini. The following contribution provides some comparative data, emphasizing similarities and differences.

Evolution of Complex Plinian Eruptions: the Late Quarternary Laacher See Case History

The 11,000 a old plinian eruption of Laacher See Volcano, the youngest of three plinian cycles in the East Eifel Volcanic Field (EEVF), took place during the summer, judging from the types of vegetation incorporated in the basal tephra layer deposited during the initial explosions.

On the Relation Between the Thera Eruption and the Destruction of Eastern Crete, c. 1450 B.C.

The idea that the Theran eruption and the desolation of the eastern half of Minoan Crete were related as cause and effect, first put forward by Professor Marinatos, has been much discussed since excavation began at Acrotiri in 1967.

Traces of the Eruption in Cyprus?

Pumice has been found in great quantities in north-western Cyprus. Sites which flourished in this part of the island were abandoned around 1500 B.C.

Primary Basaltic Magmas for the Pre-Caldera Volcanic Rocks of Santorini

The most abundant types amongst analysed volcanic rocks of the precaldera deposits of Santorini are high-alumina basalts, with 49 - 53 % SiO2 and 6 - 7 % MgO.

Some Comments on the Minoan Eruption of Santorini

The damaging factors of the main types of volcanic eruptions and the range of their effects, divided into short-reaching, far-reaching and "global", are listed in a table.

The Tsunami Caused by the Prehistoric Eruption of Thera

Assuming the original height of the Thera tsunami to have been equal in a circle around its source, the author used the evidence from Anaphi and Tel Aviv to calculate its initial height at source and its subsequent height on arrival at Amnisos.

A Santorini Eruption Unknown to Historians

In the National Library at Paris there is a manuscript on parchment, the 'Fonds Latin 4825', from the Liber Insularum Archipelagi of Christoforo Buondelmonti, which contains a rudimentary map of Santorini. Between the island of 'Santilini' and the islet of 'Tirassia' are written the following words:

Eruptions of the Santorini Volcano from Contemporary Sources

Every eruption either minor or major affects everybody in society. The nature of this reaction differs according to the level of education and the degree of superstition involved in each individual case.

Geonomic Notes on the Bronze Age Eruption of Santorini

In Paragraph 1 it is stated that the ancient crater of Stronghyle, from which a nuee ardente issued, was situated at the southeastern edge of the present-day Nea Kameni island and at a high level above the sea. In Paragraph 2 some climatological effects of the Santorini eruption are discussed on the basis of a comparison with Krakatau. In Paragraph 3 the tectonic and volcanic earthquakes that preceded, accompanied and followed the Minoan outburst are treated in accordance with the archaeological view.

Oxygen Isotope Composition of Volcanic Rocks From Santorini and Christiani

The oxygen isotope composition of 51 rocks and minerals from Santorini and Christiani has been determined. The δ 18Ο values of various lavas and rocks fall in the range between 7.2 and 13.3 ‰, the higher values over + 10 are obviously due to secondary weathering processes.

Types of Historic Eruptions and Nature of Magma in Northern Japan

During historic times eruptions have taken place at 15 volcanoes in northern Japan, of which seven volcanoes recorded phreatic explosions of small scale and eight others erupted magmatic materials manifesting a wide variation in type of eruption from Strombolian to Plinian.

Energetics of the Minoan Eruption

New mathematical models of explosive volcanic processes are used to deduce various parameters of the main phases of the Minoan eruption from the nature of the resulting deposits.